Journal of Behavioral Medicine, VoL, 15, No. 4, 1992
Elevated Serum Dehydroepiandrosterone Sulfate Levels in Practitioners of the Transcendental Meditation (TM) and TM-Sidhi Programs Jay L. Glaser, 1,4 Joel L. Brind, 2,3 Joseph H. Vogeiman, 2 Michael J. Eisner, 1 Michael C. Dillbeck, 1 R. Keith Wallace, 1 Deepak Chopra, 1 and Norman Orentreich 2 Accepted for publication October 14, 1991
Serum dehydroepiandosterone sulfate (DHEA-S) levels were measured in 270 men and 153 women who were experienced practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs, mental techniques practiced twice daily, sitting quietly with the eyes closed. These were compared according to sex and 5-year age grouping to 799 male and 453 female nonmeditators. The mean DHEA-S levels in the TM group were higher in all 11 of the age groups measured in women and in 6 of 7 5-year age groups over 40 in men. There were no systematic differences in younger men. Simple regression using TM-group data revealed that this effect was independent of diet, body mass index, and exercise. The mean TM-group levels measured in all women and in the older men were generally comparable to those of nonmeditator groups 5 to 10 years younger. These findings suggest that some characteristics of TM practitioners are modifying the age-related deterioration in DHEA-S secretion by the adrenal cortex. KEY WORDS: practitioners; serum dehydroepiandrosterone sulfate; transcendental medita-
tion.
1The Department of Physiological and Biological Sciences, Maharishi International University, Fairfield, Iowa 52556. 2The Orentreich Foundation for the Advancement of Science, Inc., Cold Spring-on-Hudson, New York 10516. 3Department of Natural Sciences, Baruch College, CUNY, New York, New York 10010. 4To whom correspondence should be addressed at Maharishi Ayur-Veda Health Center for Behavioral Medicine and Stress Management, P.O. Box 344, Lancaster, Massachusetts 01523. 327 0160-7715/92/0800-0327506.50/0 9 1992Plenum PublishingCorporation
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INTRODUCTION The serum level of the adrenal androgen, dehydroepiandrosterone sulfate (DHEA-S), is closely correlated with age in humans and has also been associated with measures of health and stress. Cross-sectional studies have indicated that serum DHEA-S levels rise throughout childhood and adolescence and attain peak levels during the midtwenties. Thereafter, DHEA-S levels decline logarithmically with age to reach values in the eighth and ninth decades that are only 20% of peak levels (Orentreich et al., 1984). Higher levels of DHEA-S have also been associated with a reduction in age-related disorders. In men over 50, but not in women, DHEA-S concentrations appear to be inversely correlated with death from both ischemic heart disease and all cardiovascular diseases as well as with death from any cause (Barrett-Connor et al., 1986). Subnormal plasma concentrations of both D H E A and DHEA-S have been associated with breast cancer (Browney et al., 1972, Wang et al., 1974) and subnormal concentrations of urinary metabolites of DHEA-S have been associated with increased risk of breast cancer up to 9 years prospectively (Bulbrook et al., 1971). Oral administration of DHEA has been noted to lower serum low-density lipoprotein levels in normal men (Nestler et al., 1988) and DHEA-S levels in women in late menopause have been found to be positively correlated with bone density (Deutsch et al., 1987). Delta-5 adrenal androgen levels may also be a reflection of stress: basal unconjugated DHEA excretion decreases in patients with chronic illness (Parker et aL, 1985b), serum DHEAS levels fall following burn trauma (Parker and Baxter, 1985), and adrenal androgens have been found to be depressed in combat troops under threat of attack (Rose et aL, 1969). Serum DHEA levels were observed to increase following improvement of the social environment of elderly individuals (Arnetz et aL, 1983). A previous report suggests that individuals over 55 practicing the Transcendental Meditation (TM) technique have a younger physiological age than a control population on a standardized index that estimates biological age using blood pressure, auditory threshold, and near-point vision (Wallace et al., 1982). In a Harvard study involving 73 elderly nursing-home residents, subjects taught TM had reduced mortality and improved cognitive flexibility, learning and word fluency compared to subjects randomized into groups receiving progressive relaxation, mindfulness therapy, or no treatment (Alexander et al., 1989). TM practitioners have also been reported to improve on other physiological and psychological parameters that tend to deteriorate with age, such as reaction time (Appelle and Oswald, 1974), latency of brain-stem auditory evoked potentials (McEvoy et al., 1980), systolic blood pressure (Wallace et al., 1983), and serum cholesterol
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levels (Cooper and Aygen, 1979). A recent study of 2000 TM practitioners subscribing to a major health insurance carrier found reduced medical utilization rates for 16 of 17 major medical treatment categories (obstetrical utilization was similar), including 55.4% fewer admissions for tumors and 87% fewer admissions for heart disease, compared with nonmeditating cohorts (Orme-Johnson, 1987), implying that TM practitioners may have lower morbidity. This lower utilization was most pronounced in the older age groups. We hypothesized that TM practice may be a behavior that elevates DHEA-S levels. As a first step, a cross-sectional study was conducted in a group of experienced TM practitioners.
METHODS
Subjects Subjects were recruited in order to give representative samples from all age groups in both sexes. Comparison subjects were members of a study reported previously and comprised 799 men and 453 women (Orentreich et al., 1984). These subjects represented a healthy fraction of the patients of a large, well-known New York City practice specializing in cosmetic dermatology who visited the practice from 1980 to 1983 for cosmetic procedures such as hair transplants, dermabrasion, and removal of warts and moles. Criteria for exclusion included the presence of major medical disorders or any disorder known to affect androgen levels. Comparison subjects had confirmation of normal serum assays for T4, T3 uptake, cortisol, testosterone, and sex hormone binding globulin and could not be taking medications known to affect androgen levels. Women in this group were not taking glucocorticoids or estrogens and had no significant acne, alopecia or hirsutism. Inclusion criteria for TM group subjects were identical except for hormone determinations: all but 38 of the men had confirmation of normal levels of serum cortisol and T4, and all but 55 had measurement of testosterone and sex hormone binding globulin. These determinations were not performed with the TM women's sera. TM-group subjects were recruited from any practitioners of the TM technique on the Maharishi International University ( M I U ) campus in Fairfield, Iowa. Campus populations were targeted for recruitment to facilitate enrollment of adequate samples from all age groups (270 men age 20 to 81 and 153 women age 20 to 74). All but 28 of the TM subjects over 45 years of age were volunteers recruited by public announcements during conferences for advanced TM practitioners held on campus from 1983 to 1987. All TM-group
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subjects under 45 and 28 subjects over 45 were recruited from MIU students, faculty, and staff and from meditating members of the Fairfield community, including senior citizen groups. Sampling of the TM group began in 1982 before the end of the sampiing period of the comparison group. All younger men and the majority of men over 45 were sampled during 1982 and 1983. Sampling of women over 45 began in 1984 and continued through 1987 due to the relative paucity of long-term meditators in the oldest age groups. Similarly, recruitment of adequate numbers for the oldest male groups was completed in 1987. All women under 45 were sampled in April 1987. All TM subjects practiced the Transcendental Meditation technique as taught by Maharishi Mahesh Yogi (Wallace, 1970). Most were advanced meditators, with a mean length of regular practice of 10.3 years for men and 11.1 years for women (range, 8 months to 26 years for all subjects). Ninetytwo percent of the women and 93% of the men were also practitioners of the more advanced TM-Sidhi program. TM is a simple, mental technique practiced twice daily (usually in the morning and evening) for 20 min, sitting comfortable with the eyes closed. During this period, the meditator remains wakeful and alert, effortlessly thinking in a prescribed manner a specific meaningless sound (mantra), and generally experiences a state of quiet inner awareness. The TM-Sidhi program is an advanced meditation technique, similarly practiced sitting with the eyes closed for an additional 20 to 30 min. In the TM-Sidhi program, instead of a meaningless mantra, the subject of meditation is a set of specific, meaningful aphorisms known as sutras (Mukerji, 1977). The physiological studies on these techniques have been reviewed in meta-analysis elsewhere (Dillbeck and Orme-Johnson, 1987). A comprehensive health questionnaire was administered to all TM subjects before venipuncture and included variables of health history, medication, physiognomy, diet, tobacco and alcohol consumption, physical exercise, sleep patterns, participation in TM and other stress reduction programs, and menstrual and endocrine parameters. This lengthy questionnaire was not given to the comparison group, who were screened from their clinical records. It is possible that some members of the comparison group were practitioners of the TM program, but this would not likely be much more than 0.5% of the population, the estimated proportion of the U.S. population practicing the technique.
Experimental Procedure Blood was drawn on TM group subjects under 45 between 10:45 and 11:45 AM; men were sampled in September and October, and women in
Elevated Dehydroepiandrosterone Sulfate in TM Practitioners
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April and May. For logistical reasons during the conferences, most TM subjects over 45 were sampled between 1:00 and 2:30 PM, after they had taken lunch; most older women were sampled in July, and men in December. Sera were drawn on comparison subjects at random times during medical office hours throughout the year. Serum was separated immediately after coagulation and the specimens were stored in hermetic polyethylene tubes at -80~ without thawing until assay. The long-term stability of DHEA-S in frozen serum has ben documented previously (Orentreich et al., 1984). Serum sodium was assayed on random samples to verify that concentration of frozen aliquots due to desiccation had not occurred.
Radioimmunoassay (RIA) of Serum DHEA-S Serum DHEA-S levels were measured by direct radioimmunoassay (Buster and Abraham, 1972) using as the radiolabeled ligand [1,2-3H] - instead of [7-3H] dehydroepiandrosterone as described by the original authors. Duplicate aliquots of serum were diluted 1:2000 to a final volume of 0.5 ml and incubated overnight with 12,000 dpm of tracer (in 0.1 ml) and 0.1 ml of antiserum (Environmental and Endocrine Products, Cliffside Park, N J). The unbound steroid was removed with dextran~ charcoal, and an aliquot of the supernatant was counted. The cross-reactivity of the rabbit antiserum with unconjugated (free) D H E A was 100%. The results, therefore, represent the sum of serum D H E A and DHEA-S, although the contribution from D H E A is negligible because of the thousandfold greater abundance of DHEA-S in serum. Other steroids did not contribute more than 0.02 gg/dl to the assay values. The sensitivity of the method was 0.004 p.g/assay tube, equivalent to 16.0 gg/dl serum (Abraham, 1975). Sera which contained less than 40 ~tg/dl were reassayed at a 1:500 dilution (detection limit, 4.0 gg/dl). The mean intraassay coefficient of variation was 10%, and the maximum interassay coefficient of variation (n = 6) was 12% for the range 47 to 413 gg/dl. Although sera from the comparison and TM groups were assayed in different batches, inclusion of random samples from subjects in the comparison group as well as standardized sera were included with all assays, and there was no drift in the assay over time. Statistical Methods
Data were analyzed by 5-year age groups, i.e., 20-24, 25-29, 30-34, 35-39, 40-44, 45--49, 50-54, 55-59, 60-64, 65-69, and 70-74 (for men the oldest category was 70+ years, since male meditators up to 81 were included). Analysis of variance was performed using a two-way design of age
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vs. T M status (i.e., meditator or nonmeditator), with correction for multiple comparisons. Since the distribution of D H E A - S for all age groups was skewed toward higher values, the logarithm of the D H E A - S value was taken as the dependent variable to normalize the distribution curve. In addition, analysis of variance was performed on nonlogarithmic, normalized data, in which each value was expressed as a percentage of the mean. Simple regression was used to control for other life-style variables which could have influenced D H E A - S levels. For regression, T M group D H E A - S was expressed as a percentage of the mean for comparison subjects of the same age to control for the observed decline of D H E A - S values with age.
RESULTS The mean serum D H E A - S levels (i.e., ant• of mean logarithmic D H E A - S ) in all age groups are summarized in Tables I and II and Figs. 1 and 2. Analysis of variance revealed that there were significant systematic effects for both age and T M practice, accounting for the differences in group mean D H E A - S levels. The effect of age was significant for both men and women [F(10,1047) = 53.88, p < .0001, and F(10,585) = 31.67, p < .0001, respectively]. This reflected a progressive decline of D H E A - S with increasing age, as found in prior studies. The effect of T M practice was also significant [F(1,1047) = 16.03, p = .0001 for men and F(1,585) = 17.55, p < .0001 for women]. T M participants showed higher levels than
Table I. Serum DHEA-S Concentrations (• SEM) in 1069 Men for Comparison and TM Groups Comparison group Age group 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70+ Total
N 216 151 82 70 63 59 53 40 27 20 18 799
DHEA-S level (~g/dl) 347• 314• 325• 294• 215_+21 182• 126• 147• 98• 92• 59•
TM group N 11 33 44 66 8 27 20 25 15 11 10 270
DHEA-S level (~g/dl) 350• 341• 317• 249• 229• 205• 195• 127• 137• 127• 130•
% Elevation in TM group 1 8 -2 -15 6 13 54 -14 40 37 121
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Elevated Dehydroepiandrosterone Sulfate in TM Practitioners
Table II. Serum DHEA-S Concentrations (• SEM) in 606 Women for Comparison and TM Groups Comparison group Age group
N
20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 Total
54 65 52 54 44 51 39 28 36 19 11 453
TM group
DHEA-S level (llg/dl)
N
2302-_27 217• 159-+18 137• 127• 88• 7ffZ--12 61• 56_+08 43• 46•
DHEA-S level (gg/dl)
% Elevation in TM group
269-2-42 221• 218• 176+-21 162• 117• 108• 78• 98• 56• 54•
17 2 37 28 28 34 54 29 76 30 17
11 10 13 15 10 30 16 14 11 18 5 153
4OO
350 ~
~
Men |
3OO
C o m p a r i s o n Group
250 200 w
,,1I~
150
E :~
100
i..,
50
0 20-24
25129 30'-34 35139 4o I`4`4 45149 50'-54 55159 60164 c51c,9 70,, Age (years)
Fig. 1. Serum DHEA-S concentrations (• vs. age in men. Group mean DHEA-S levels are displayed according to 5-year age grouping in the TM group (open circles) and comparison group (filled circles). In both groups, DHEA-S decreases with age. There are no systematic differences in DHEA-S levels in the younger age groups, but TM group levels are higher in six of seven age groups over 40 years. The DHEA-S concentrations shown represent the antilog of group mean log DHEA-S values. The curves obtained were fitted to the data using the equation a x ~ b x 2 + cx +d.
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Glaser et al. 400
Women 350
_ A
9
Comparison
Group
300
"0 ::=L
250
v
O3 IM "IQ
200
150
E "-i
100
t,
t.~ 50
0
i 20-24
, 25-29
i 30-34
i 35-39
i 40-,~4
~ z-5-49
~ 50-54
i 55~59
i 60-64
i 65-69
i 70-74
Age (years) Fig. 2. Serum DHEA-S concentrations (_+SEM) vs. age in women. DHEA-S declines with age in both the TM and the comparison groups, and the TM-group values are higher in all age groups. TM-group values are characteristic of comparison-group women 5 to 10 years younger.
the comparison group for both men and women. Similar significance was found using nonlogarithmic, normalized data. For men, but not for women, there was also a significant interaction [F(10,1047) = 4.18, p -- .0001] between TM practice and age: TM practice had a significant effect only in older male age groups. A test of simple main effects for each male age group was significant (F>3) for the groups 35-39, 50-54, 60-64, 65-69, and 70+ (p < .05). All four of the significant or near-significant simple main effects for men over 40 were in the direction of TM participants having higher values. Simple main effects were not determined for women since an interaction was not observed. In all 11 of the measured age groups in women, the mean DHEA-S levels of the TM group were higher than for the nonmeditators. There were several variables recorded from the TM-group subjects that differed from the norm and that conceivably could account for the observed differences in DHEA-S levels. A high proportion of subjects, mostly from the younger age groups, was vegetarian (40% of women and 59% of men). In women, there was no correlation between meat consumption and DHEA-S elevation (r = -.009). In men, meat consumption was positively correlated with DHEA-S elevations (r = .20). This was attributed to the fact that nonvegetarians were predominantly in age groups over 40,
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the only male groups in which DHEA-S elevations were observed. Similarly, exercise and indices of obesity (body mass index and deviation from ideal weight) were not correlated with DHEA-S elevation (r < .15 for all values). Because so few TM subjects used tobacco or alcohol, it was not possible to analyze these factors as contributing variables. Although 49% of the male and 55% of the female members of the TM group were former smokers, and 32% of the men and 29% of the women were smoking at the time of instruction in TM, only 0.7% of the men and 1.9% of the women still smoked at the time of the study. This is probably considerably different from the nonmeditators, for whom data on smoking activity were not collected. In the population at large, for similar age groups, the incidence of smoking was 37% for men and 28% for women (National Center for Health Statistics, 1985). Similarly, only 9% of TM practitioners consumed any alcohol.
DISCUSSION The data presented here reveal that men over 45 and women of all age groups, who are experienced practitioners of the TM and TM-Sidhi programs, have serum DHEA-S concentrations that are higher than those found in a healthy, normal, nonmeditating population consulting dermatologists for cosmetic reasons and reported previously by the same laboratory. Two important questions must be addressed: first, whether the comparison between groups is valid; and second, whether these findings are the result of regular practice of the TM program or whether they reflect another characteristic of the TM group or some other experimental effect. It is unlikely that the observed differences are due to the selection of the comparison population. Comparison subjects represented healthy clients who visited a cosmetic surgery/dermatology practice, but these values are probably representative of North American values in general. Virtually identical data for each age grouping were obtained from 517 normal female participants in a multiphasic health screening program of the (Kaiser) Permanente Medical Group, Oakland, CA (Orentreich et al., 1984) and from 98 normal male participants in the Baltimore Longitudinal Study on Aging (Orentreich et al., manuscript in preparation). Although the TM-group subjects were different from normal populations in their reduced consumption of tobacco, alcohol, and meat, as noted above, as well as of prescribed and nonprescribed drugs, the observed results could not be attributed to any of these factors. Analysis indicated that vegetarianism did not make a systematic contribution to the elevated mean DHEA-S levels. This conclusion is supported by the findings of
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Schultz and Keklem (1983), who measured DHEA-S of 159 _+ 65 Bg/dl in vegetarian women (mean age, 32.6) vs. 176 + 48 ~tg/dl in nonvegetarians (mean age, 32.0), and by H/im/il/iinen et al. (1984) who did not observe any change in DHEA-S in 30 men transferred from a diet high in saturated fat and animal protein to an experimental diet consisting mostly of fruit, vegetables, vegetable oils, and fish. In addition, Hill et al. (1977) did not observe any change in D H E A levels in four female nurses who were switched to a low-fat vegetarian diet. It is also improbable that the lack of smokers in the TM group contributed to the differences, since cigarette smoking has been found to increase DHEA-S as well as androstenedione levels in both women (Khaw et al, 1988) and men (Barrett-Connor and Khaw, 1987). These findings appear, at first, to be paradoxical and to cast doubt on the validity of DHEA-S as a marker of aging. However, it is known that the human lung has considerable capacity to metabolize DHEA-S, both to other sulfoconjugates (Menzel et al., 1970) and to unconjugated steroids (Milewich et al., 1983), and to metabolize androstenedione (Milewich et al., 1977). Consequently, cigarette smoking may impair normal pulmonary clearance of adrenal androgens, a finding which has been demonstrated in the rat (Hartiala et al., 1978). Thus, any aging study in which the test population has compromised pulmonary function relative to a healthy population, including exposure to tobacco smoke, could not rely on DHEA-S as an aging marker. In the present study, the strong likelihood of a higher smoking incidence in the comparison group (though not measured) than in the meditators might simply raise the "noise" level of DHEA-S in the comparison group and mask DHEA-S elevations in the TM group due to other factors. We are not aware of any studies indicating an influence of alcohol on DHEA-S. We could also not explain any difference in the two populations from the sampling methods. The DHEA-S levels used for the comparison group norms were assayed under identical conditions in the same laboratory. Although assaying of meditator sera continued 3 years longer than the comparison group, many assays were contemporaneous. DHEA-S, unlike D H E A and other androgens, is secreted into a large plasma pool with a half-life of 10-20 hr and, therefore, does not display large circadian or ultradian rhythmic fluctuations (Rosenfeld et al., 1975). Several recent studies, however, have shown small but significant circadian rhythms in plasma DHEA-S by cosinor analysis in young (but not old) men (Del-Ponte et al., 1990; Montanini et al., 1988) and women (Carandente et al., 1990). These studies are remarkable for the strong agreement among them: all showed amplitudes of 11-15% of the mesor and an acrophase between approximately 2:00 and 4:00 PM for subjects of younger ages (21-23 years). While the lack of rhythmicity in the older men would rule out the timing of sampling as a source
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of bias in our older men, a small bias might be expected in the case of younger women, since the comparison group was randomly sampled throughout the workday. However, the amplitude of the circadian rhythm is in the same range as the variability of the DHEA-S assay itself and smaller than the daily variability (Orentreich et al., 1984). Moreover, DHEA-S remains at a broad plateau about the mesor through most of the workday hours following a 10:00 AM nadir (Carandente et al., 1990). Since the younger meditators were all sampled between 10:45 and 11:45 AM, any sampling bias due to circadian variation would tend to mask rather than exaggerate the observed elevations of DHEA-S in young female meditators. Sonka suggests that fasting may increase D H E A excretion (Sonka, 1976), but we are not aware of any postprandial changes in DHEA-S which could account for the elevated levels in the older group, who were sampled in the early afternoon. Similarly, no significant monthly, seasonal, or annual rhythms have been observed in men (Orentreich et al., 1984), and the 28% circatrigintan variation in DHEA-S observed with menses (Sinkl6si et al., 1984) would be expected to be distributed approximately uniformly across the subjects in both groups. One must finally consider whether the TM group represents a selfselected group that may have had other characteristics responsible for maintaining elevated levels of DHEA-S. If individuals who began TM tended to be healthier than the population at large, or if only the healthiest older meditators attended meditation conferences and volunteered for this study, then this may have provided a skewed sample of healthier individuals with a younger physiological age, who conceivably might have higher concentrations of DHEA-S. The same exclusion criteria were utilized for both TM and comparison groups. Since data have been published indicating that TM practitioners have lower health-care utilization (Orme-Johnson, 1978), TM subject recruitment was designed to avoid selection bias. Nevertheless, the possibility of selection bias remains an important confounder of these data that cannot be dismissed. This raises an important question that has not yet been sufficiently investigated: whether DHEA-S levels are related not only to age, but also to the general state of health, including the presence of chronic disorders, debility, stressors, and other life-style variables. If chronic disease and stress prove to be associated with subnormal DHEA-S levels, this could help explain our findings, because many of the physiological changes observed both during and outside the practice of the TM technique are opposite to those occurring in the acute and chronic adaption response to stressors: decreased plasma cortisol (Jevning et al., 1978), attenuated catecholamine production during exercise (Lang et al., 1979), increased 5-hydroxyindole3-acetic acid excretion (Bujatti and Riederer, 1976), reduced metabolism
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in resting forearm muscle and decreased blood lactate (Jevning et al., 1983a), and other physiological changes suggestive of decreased autonomic and metabolic activation (Wallace et al., 1983; Jevning et al., 1983b). The age-related decline in serum DHEA-S levels is probably due to reduced secretion by the adrenal cell, since nearly all DHEA-S production can be traced to the adrenal in both men and women, since DHEA-S is not stored in the adrenal cortex, and since its metabolic clearance rate declines slightly with age (Vermeulen, 1980; Laatikainen et al., 1971; Rivarola et al., 1967). This implies that some mechanism in the TM group is preventing the usual age-related reduction in those biochemical processes leading to delta-5 androgen production by the adrenal cell. If factors besides age, such as stress, general health, and other life-style variables, modify DHEA-S levels in normal individuals, then it would not be surprising that DHEA-S elevations were also found in younger TM groups. It is not clear why these elevations were found in younger women but not in younger men. Since TM practitioners have been shown to have an attenuated autonomic response to stressors (Orme-Johnson, 1973), the higher DHEA-S levels seen in the TM group may reflect protection against chronic overstimulation of the adrenal in response to stress. In support of this, Parker et al. (1985a,b) found reduced DHEA-S/cortisol ratios in patients under conditions of prolonged, severe illness and suggested that mineralocorticoid and adrenal androgen synthetic mechanisms may have been shifted to glucocorticoid production, which is essential to survival. The age-related decline in DHEA-S, which appears to be retarded in the TM group, may be due to decreased adrenal-cell responsiveness to ACTH (Pavlov et al., 1986) or some other factor, due to shunting to glucocorticoid pathways, or intrinsic to the adrenal cell. Since delta-5 androgens have been shown to be produced in primate brain, it is also conceivable that meditation may be altering neurosteroid production in the central nervous system (Robel et al., 1987). It is still unclear whether higher DHEA-S levels significantly contribute to longevity and improved health in older individuals or whether elevated D H E A - S levels simply reflect the lack of cumulative physical deterioration due to age, chronic stress, and illness. There are many reasons to suspect the latter in the difference between the two groups under study. Although comparisons of general health were not made in this particular study, the insurance study cited earlier (Orme-Johnson, 1987), showing reduced health-care utilization rates in TM practitioners, especially in the oldest groups studied, used a population of meditators including many from MIU and the surrounding community, implying that the meditators may indeed have been healthier. Since TM practice is a behavior that has been
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shown to modify numerous other physiological, psychological, and behavioral parameters, we doubt that the observed elevations in DHEA-S are primarily responsible for TM's effect on health utilization and other agerelated parameters.
ACKNOWLEDGMENTS
The authors gratefully acknowledge Clark T. Sawin, M.D., for his review of the manuscript and Kiavdia Chervinsky, Despina Marinescu, Kokila Patel, Bill Crosson, and Tom Moriarty for their skilled technical assistance.
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Dillbeck, M. C., and Orme-Johnson, D. W. (1987). Physiological differences between Transcendental Meditation and rest. Am. Psychol. 42: 879. H~im~il~iinen, E., Adlercreutz, H., Puska, P., and Pietinen, P. (1984). Diet and serum sex hormones in healthy men. J. Steroid Biochem. 20: 459. Hartiala, J., Uotila, P., and Nienstedt, W. (1978). The effects of cigarette smoke exposure on testosterone metabolism in the isolated perfused rat lung. J. Steroid Biochem. 9: 365. Hill, P., Chan, P., Cohen, L., Wynder, E., and Duno, K. (1977). Diet and endocrine-related cancer. Cancer 39: 1820. Jevning, R., Wilson, A. F., and Davidson, M. J. (1978). Adrenocortical activity during meditation. Horm. Behav. 10: 54. Jevning, R., Wilson, A. F., O'Halloran, J. P., and Walsh, R. N. (1983a). Forearm blood flow and metabolism during acute stylized and unstylized states of decreased activation. Am. Z Physiol. 245: Rll0. Jevning, R., Wilson, A. F., Pirkle, H., O'Halloran, J. P., and Walsh, R. N. (1983b). Metabolic control in a state of decreased activation: Modulation of red cell metabolism. Am. J. Physiol. 245 (Cell. Physiol. 14): C457. Khaw, K.-T., Tazuke, S., and Barrett-Connor, E. (1988). Cigarette smoking and levels of adrenal androgens in postmenopausal women. N. Engl. J. Med. 318: 1705. Laatikainen, T., Laitinen, E. A., and Vihko, R. (1971). Secretion of free and sulfate conjugated neutral steroids by the human testis. Effect of administration of human chorionic gonadotropin. J. Clin. Endocrinol. Metab. 32: 59. Lang, R., Dehof, K., and Meurer, K. A. (1979). Sympathetic activity and Transcendental Meditation. J. Neural Trans. 44: 117. McEvoy, T. M., Frumkin, L. R., and Harkings, S. W. (1980). Effects of meditation on brain-stem auditory evoked potentials. Int. J. Neurosci. 10: 165. Menzel, P., Penzes, L., Mattzander, U., and Oertel, G. W. (1970). In vivo perfusion of human lung tissue with 7-alpha- 3H-dehydroepiandrosterone 35S-sulfate. Metabolism of steroid conjugates. IV. Experientia 26: 657. Milewich, L., Winters, A. J., Stephens, P., and MacDonald, P. C. (1977). Metabolism of dehydroisoandrosterone and androstenedione by the human lung in vitro. J. Steroid Biochem. 8: 277. Milewich, L., Garcia, R. L., and Johnson, A. R, (1983). Steroid sulfatase activity in human lung tissue and in endothelial pulmonary cells in culture. J. Clin. EndocrinoL Metab. 57: 8. Montanini, V., Simoni, M., Chiossi, G., Baraghini, G. F., Velardo, A., Baraldi, E., and Marrama, P. (1988). Age-related changes in plasma dehydroepiandrosterone sulphate, cortisol, testosterone and free testosterone circadian rhythms in adult men. Horm. Res. 29: 1. Mukerji, P. N. (ed.) (1977). Yoga Philosophy of Patanjali; University of Calcutta Press, Calcutta, p. 279. National Center for Health Statistics, U.S. Department of Health and Human Services, Public Health Service. (1985). Provisional data from the Health Promotion and Disease Prevention Supplement to the National Health Interview Survey: United States, January-March 1985, U.S. Government Printing Office, Washington, D.C. Nestler, J. E., Barlascini, C. O., Clore, J. N., and Blackard, W. G. (1988). Dehydroepiandrosterone reduces serum low density lipoprotein levels and body fat but does not alter insulin sensitivity in normal men. J. Clin. Endocrinol. Metab. 66: 57. Orentreich, N., Brind, J. L., Rizer, R. L., and Vogelman, J. H. (1984). Age changes and sex differences in serum dehydroepiandrosterone sulfate concentrations throughout adulthood. J. Clin. Endocrinol. Metab. 59: 551. Orme-Johnson, D. W. (1973). Autonomic stability and Transcendental Meditation. Psychosom. Med. 35: 341. Orme-Johnson, D. W. (1987). Medical care utilization and the Transcendental Meditation program. Psychosom. Med. 49: 493. Parker, L., Eugene, J., Farber, D., Lifrak, E., Lai, M., and Juler, G. (1985a). Dissociation of adrenal androgen and cortisol levels in acute stress. Horm. Metab. Res. 17(4): 209.
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Parker, L. N., Levin, E. R., and Lifrak, E. T. (1985b). Evidence for adrenocortical adaptation to severe stress. J. Clin. EndrocrinoL Metab. 60: 947. Parker, R. C., and Baxter, C. R. (1985). Divergence in adrenal steroid secretory pattern after thermal injury in adult patients. J. Trauma 25: 508. Pavlov, E. P., Harman, S. M., Chrousos, G. P., Loriaux, D. L., and Blackman, M. R. (1986). Responses of plasma adrenocorticotropin, cortisol, and dehydroepiandrosterone to ovine corticotropin-releasing hormone in healthy aging men. J. Clin. EndrocrinoL Metab. 62: 767. Rivarola, M. A., Saez, J. M., Jones, H. W., Jones, S. G., and Migeon, C. J. (1967). Metabolic clearance rate and blood production rate of testosterone and androst-4-ene-3,17-dione under basal conditions, ACTH and hCG stimulation. Comparison of urinary production rate of testosterone. J. Clin. EndocrinoL Metab. 26: 1203. Robel, P., Bourreau, E., Corpechot, Dang, D. C., Halberg, F., Clarke, C., Haug, M., Schlegel, M. L., Synguelakis, M., Vourch, C., and Baulieu, E.-E. (1987). Neurosteroids: 3-13-Hydroxy-delta-5-derivatives in rat and monkey brain. J. Ster. Biochem. 27: 649. Rose, R. M., Bourne, P. G., Poe, R. O., Mougey, E. H., Collins, D. R., and Mason, J. W. (1969). Androgen responses to stress II. Excretion of testosterone, epitestosterone, androsterone and etiocholanolone during basic combat training and under threat of attack. Psychosom. Med. 31: 418. Rosenfeld, R. S., Rosenberg, B. J., Fukushima, D. K., and Hellman, L. (1975). 24-Hour secretory pattern of dehydroepiandrosterone and dehydroepiandrosterone sulfate. J. Clin. EndrocrinoL Metab. 40: 850. Schultz, T. D., and Keklem, J. E. (1983). Nutrient intake and hormonal status of premenopausal vegetarian Seventh-Day Adventists and premenopausal nonvegetafians. Nutr. Cancer 4: 247. Sikl6si, G., Hintalan, A., Csomor, S., Bakos, L., Sikl6s, P., Olajos, F., and Marcsek. (1984). Episodic secretion of hormones and the diagnostic value of single blood estimates. III. Testosterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulphate, cortisol. Acta Med. Hung. 41: 213. Sonka, J. (1976). Dehydroepiandrosterone~Metabolic effects. Acta Univ. Carol Med. 53: 1. Verrneulen, A. (1980). Adrenal androgens and aging. In Genazzani, A. R., Thijssen, J. H. H., and Siiteri, P. K. (eds.), Adrenal Androgens; Raven Press, New York, p. 215. Wallace, R. K. (1970). Physiological effects of Transcendental Meditation. Science 167: 1751. Wallace, R. K., Dillbeck, M., Jacobe, E., and Harrington, B. (1982). The effects of the Transcendental Meditation and TM-Sidhi program on the aging process. Int. J. Neurosci. 16: 53. Wallace, R. K., Silver, J., Mills, P. J., Dillbeck, M. C., and Wagoner, D. E. (1983). Systolic blood pressure and long-term practice of the Transcendental Meditation and TM-Sidhi program: Effects of TM on systolic blood pressure. Psychosom. Med. 45: 41. Wang, D. Y., Bulbrook, R. D., Herian, M., and Hayward, J. L. (1974). Studies on the sulphate esters of dehydroepiandrosterone and androsterone in the blood of women with breast cancer. Eur. J. Cancer 19: 477.
Elevated Serum Dehydroepiandrosterone Sulfate Levels in Practitioners of the Transcendental Meditation (TM) and TM-Sidhi Programs Jay L. Glaser, 1,4 Joel L. Brind, 2,3 Joseph H. Vogeiman, 2 Michael J. Eisner, 1 Michael C. Dillbeck, 1 R. Keith Wallace, 1 Deepak Chopra, 1 and Norman Orentreich 2 Accepted for publication October 14, 1991
Serum dehydroepiandosterone sulfate (DHEA-S) levels were measured in 270 men and 153 women who were experienced practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs, mental techniques practiced twice daily, sitting quietly with the eyes closed. These were compared according to sex and 5-year age grouping to 799 male and 453 female nonmeditators. The mean DHEA-S levels in the TM group were higher in all 11 of the age groups measured in women and in 6 of 7 5-year age groups over 40 in men. There were no systematic differences in younger men. Simple regression using TM-group data revealed that this effect was independent of diet, body mass index, and exercise. The mean TM-group levels measured in all women and in the older men were generally comparable to those of nonmeditator groups 5 to 10 years younger. These findings suggest that some characteristics of TM practitioners are modifying the age-related deterioration in DHEA-S secretion by the adrenal cortex. KEY WORDS: practitioners; serum dehydroepiandrosterone sulfate; transcendental medita-
tion.
1The Department of Physiological and Biological Sciences, Maharishi International University, Fairfield, Iowa 52556. 2The Orentreich Foundation for the Advancement of Science, Inc., Cold Spring-on-Hudson, New York 10516. 3Department of Natural Sciences, Baruch College, CUNY, New York, New York 10010. 4To whom correspondence should be addressed at Maharishi Ayur-Veda Health Center for Behavioral Medicine and Stress Management, P.O. Box 344, Lancaster, Massachusetts 01523. 327 0160-7715/92/0800-0327506.50/0 9 1992Plenum PublishingCorporation
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INTRODUCTION The serum level of the adrenal androgen, dehydroepiandrosterone sulfate (DHEA-S), is closely correlated with age in humans and has also been associated with measures of health and stress. Cross-sectional studies have indicated that serum DHEA-S levels rise throughout childhood and adolescence and attain peak levels during the midtwenties. Thereafter, DHEA-S levels decline logarithmically with age to reach values in the eighth and ninth decades that are only 20% of peak levels (Orentreich et al., 1984). Higher levels of DHEA-S have also been associated with a reduction in age-related disorders. In men over 50, but not in women, DHEA-S concentrations appear to be inversely correlated with death from both ischemic heart disease and all cardiovascular diseases as well as with death from any cause (Barrett-Connor et al., 1986). Subnormal plasma concentrations of both D H E A and DHEA-S have been associated with breast cancer (Browney et al., 1972, Wang et al., 1974) and subnormal concentrations of urinary metabolites of DHEA-S have been associated with increased risk of breast cancer up to 9 years prospectively (Bulbrook et al., 1971). Oral administration of DHEA has been noted to lower serum low-density lipoprotein levels in normal men (Nestler et al., 1988) and DHEA-S levels in women in late menopause have been found to be positively correlated with bone density (Deutsch et al., 1987). Delta-5 adrenal androgen levels may also be a reflection of stress: basal unconjugated DHEA excretion decreases in patients with chronic illness (Parker et aL, 1985b), serum DHEAS levels fall following burn trauma (Parker and Baxter, 1985), and adrenal androgens have been found to be depressed in combat troops under threat of attack (Rose et aL, 1969). Serum DHEA levels were observed to increase following improvement of the social environment of elderly individuals (Arnetz et aL, 1983). A previous report suggests that individuals over 55 practicing the Transcendental Meditation (TM) technique have a younger physiological age than a control population on a standardized index that estimates biological age using blood pressure, auditory threshold, and near-point vision (Wallace et al., 1982). In a Harvard study involving 73 elderly nursing-home residents, subjects taught TM had reduced mortality and improved cognitive flexibility, learning and word fluency compared to subjects randomized into groups receiving progressive relaxation, mindfulness therapy, or no treatment (Alexander et al., 1989). TM practitioners have also been reported to improve on other physiological and psychological parameters that tend to deteriorate with age, such as reaction time (Appelle and Oswald, 1974), latency of brain-stem auditory evoked potentials (McEvoy et al., 1980), systolic blood pressure (Wallace et al., 1983), and serum cholesterol
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levels (Cooper and Aygen, 1979). A recent study of 2000 TM practitioners subscribing to a major health insurance carrier found reduced medical utilization rates for 16 of 17 major medical treatment categories (obstetrical utilization was similar), including 55.4% fewer admissions for tumors and 87% fewer admissions for heart disease, compared with nonmeditating cohorts (Orme-Johnson, 1987), implying that TM practitioners may have lower morbidity. This lower utilization was most pronounced in the older age groups. We hypothesized that TM practice may be a behavior that elevates DHEA-S levels. As a first step, a cross-sectional study was conducted in a group of experienced TM practitioners.
METHODS
Subjects Subjects were recruited in order to give representative samples from all age groups in both sexes. Comparison subjects were members of a study reported previously and comprised 799 men and 453 women (Orentreich et al., 1984). These subjects represented a healthy fraction of the patients of a large, well-known New York City practice specializing in cosmetic dermatology who visited the practice from 1980 to 1983 for cosmetic procedures such as hair transplants, dermabrasion, and removal of warts and moles. Criteria for exclusion included the presence of major medical disorders or any disorder known to affect androgen levels. Comparison subjects had confirmation of normal serum assays for T4, T3 uptake, cortisol, testosterone, and sex hormone binding globulin and could not be taking medications known to affect androgen levels. Women in this group were not taking glucocorticoids or estrogens and had no significant acne, alopecia or hirsutism. Inclusion criteria for TM group subjects were identical except for hormone determinations: all but 38 of the men had confirmation of normal levels of serum cortisol and T4, and all but 55 had measurement of testosterone and sex hormone binding globulin. These determinations were not performed with the TM women's sera. TM-group subjects were recruited from any practitioners of the TM technique on the Maharishi International University ( M I U ) campus in Fairfield, Iowa. Campus populations were targeted for recruitment to facilitate enrollment of adequate samples from all age groups (270 men age 20 to 81 and 153 women age 20 to 74). All but 28 of the TM subjects over 45 years of age were volunteers recruited by public announcements during conferences for advanced TM practitioners held on campus from 1983 to 1987. All TM-group
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subjects under 45 and 28 subjects over 45 were recruited from MIU students, faculty, and staff and from meditating members of the Fairfield community, including senior citizen groups. Sampling of the TM group began in 1982 before the end of the sampiing period of the comparison group. All younger men and the majority of men over 45 were sampled during 1982 and 1983. Sampling of women over 45 began in 1984 and continued through 1987 due to the relative paucity of long-term meditators in the oldest age groups. Similarly, recruitment of adequate numbers for the oldest male groups was completed in 1987. All women under 45 were sampled in April 1987. All TM subjects practiced the Transcendental Meditation technique as taught by Maharishi Mahesh Yogi (Wallace, 1970). Most were advanced meditators, with a mean length of regular practice of 10.3 years for men and 11.1 years for women (range, 8 months to 26 years for all subjects). Ninetytwo percent of the women and 93% of the men were also practitioners of the more advanced TM-Sidhi program. TM is a simple, mental technique practiced twice daily (usually in the morning and evening) for 20 min, sitting comfortable with the eyes closed. During this period, the meditator remains wakeful and alert, effortlessly thinking in a prescribed manner a specific meaningless sound (mantra), and generally experiences a state of quiet inner awareness. The TM-Sidhi program is an advanced meditation technique, similarly practiced sitting with the eyes closed for an additional 20 to 30 min. In the TM-Sidhi program, instead of a meaningless mantra, the subject of meditation is a set of specific, meaningful aphorisms known as sutras (Mukerji, 1977). The physiological studies on these techniques have been reviewed in meta-analysis elsewhere (Dillbeck and Orme-Johnson, 1987). A comprehensive health questionnaire was administered to all TM subjects before venipuncture and included variables of health history, medication, physiognomy, diet, tobacco and alcohol consumption, physical exercise, sleep patterns, participation in TM and other stress reduction programs, and menstrual and endocrine parameters. This lengthy questionnaire was not given to the comparison group, who were screened from their clinical records. It is possible that some members of the comparison group were practitioners of the TM program, but this would not likely be much more than 0.5% of the population, the estimated proportion of the U.S. population practicing the technique.
Experimental Procedure Blood was drawn on TM group subjects under 45 between 10:45 and 11:45 AM; men were sampled in September and October, and women in
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April and May. For logistical reasons during the conferences, most TM subjects over 45 were sampled between 1:00 and 2:30 PM, after they had taken lunch; most older women were sampled in July, and men in December. Sera were drawn on comparison subjects at random times during medical office hours throughout the year. Serum was separated immediately after coagulation and the specimens were stored in hermetic polyethylene tubes at -80~ without thawing until assay. The long-term stability of DHEA-S in frozen serum has ben documented previously (Orentreich et al., 1984). Serum sodium was assayed on random samples to verify that concentration of frozen aliquots due to desiccation had not occurred.
Radioimmunoassay (RIA) of Serum DHEA-S Serum DHEA-S levels were measured by direct radioimmunoassay (Buster and Abraham, 1972) using as the radiolabeled ligand [1,2-3H] - instead of [7-3H] dehydroepiandrosterone as described by the original authors. Duplicate aliquots of serum were diluted 1:2000 to a final volume of 0.5 ml and incubated overnight with 12,000 dpm of tracer (in 0.1 ml) and 0.1 ml of antiserum (Environmental and Endocrine Products, Cliffside Park, N J). The unbound steroid was removed with dextran~ charcoal, and an aliquot of the supernatant was counted. The cross-reactivity of the rabbit antiserum with unconjugated (free) D H E A was 100%. The results, therefore, represent the sum of serum D H E A and DHEA-S, although the contribution from D H E A is negligible because of the thousandfold greater abundance of DHEA-S in serum. Other steroids did not contribute more than 0.02 gg/dl to the assay values. The sensitivity of the method was 0.004 p.g/assay tube, equivalent to 16.0 gg/dl serum (Abraham, 1975). Sera which contained less than 40 ~tg/dl were reassayed at a 1:500 dilution (detection limit, 4.0 gg/dl). The mean intraassay coefficient of variation was 10%, and the maximum interassay coefficient of variation (n = 6) was 12% for the range 47 to 413 gg/dl. Although sera from the comparison and TM groups were assayed in different batches, inclusion of random samples from subjects in the comparison group as well as standardized sera were included with all assays, and there was no drift in the assay over time. Statistical Methods
Data were analyzed by 5-year age groups, i.e., 20-24, 25-29, 30-34, 35-39, 40-44, 45--49, 50-54, 55-59, 60-64, 65-69, and 70-74 (for men the oldest category was 70+ years, since male meditators up to 81 were included). Analysis of variance was performed using a two-way design of age
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vs. T M status (i.e., meditator or nonmeditator), with correction for multiple comparisons. Since the distribution of D H E A - S for all age groups was skewed toward higher values, the logarithm of the D H E A - S value was taken as the dependent variable to normalize the distribution curve. In addition, analysis of variance was performed on nonlogarithmic, normalized data, in which each value was expressed as a percentage of the mean. Simple regression was used to control for other life-style variables which could have influenced D H E A - S levels. For regression, T M group D H E A - S was expressed as a percentage of the mean for comparison subjects of the same age to control for the observed decline of D H E A - S values with age.
RESULTS The mean serum D H E A - S levels (i.e., ant• of mean logarithmic D H E A - S ) in all age groups are summarized in Tables I and II and Figs. 1 and 2. Analysis of variance revealed that there were significant systematic effects for both age and T M practice, accounting for the differences in group mean D H E A - S levels. The effect of age was significant for both men and women [F(10,1047) = 53.88, p < .0001, and F(10,585) = 31.67, p < .0001, respectively]. This reflected a progressive decline of D H E A - S with increasing age, as found in prior studies. The effect of T M practice was also significant [F(1,1047) = 16.03, p = .0001 for men and F(1,585) = 17.55, p < .0001 for women]. T M participants showed higher levels than
Table I. Serum DHEA-S Concentrations (• SEM) in 1069 Men for Comparison and TM Groups Comparison group Age group 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70+ Total
N 216 151 82 70 63 59 53 40 27 20 18 799
DHEA-S level (~g/dl) 347• 314• 325• 294• 215_+21 182• 126• 147• 98• 92• 59•
TM group N 11 33 44 66 8 27 20 25 15 11 10 270
DHEA-S level (~g/dl) 350• 341• 317• 249• 229• 205• 195• 127• 137• 127• 130•
% Elevation in TM group 1 8 -2 -15 6 13 54 -14 40 37 121
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Table II. Serum DHEA-S Concentrations (• SEM) in 606 Women for Comparison and TM Groups Comparison group Age group
N
20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 Total
54 65 52 54 44 51 39 28 36 19 11 453
TM group
DHEA-S level (llg/dl)
N
2302-_27 217• 159-+18 137• 127• 88• 7ffZ--12 61• 56_+08 43• 46•
DHEA-S level (gg/dl)
% Elevation in TM group
269-2-42 221• 218• 176+-21 162• 117• 108• 78• 98• 56• 54•
17 2 37 28 28 34 54 29 76 30 17
11 10 13 15 10 30 16 14 11 18 5 153
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150
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25129 30'-34 35139 4o I`4`4 45149 50'-54 55159 60164 c51c,9 70,, Age (years)
Fig. 1. Serum DHEA-S concentrations (• vs. age in men. Group mean DHEA-S levels are displayed according to 5-year age grouping in the TM group (open circles) and comparison group (filled circles). In both groups, DHEA-S decreases with age. There are no systematic differences in DHEA-S levels in the younger age groups, but TM group levels are higher in six of seven age groups over 40 years. The DHEA-S concentrations shown represent the antilog of group mean log DHEA-S values. The curves obtained were fitted to the data using the equation a x ~ b x 2 + cx +d.
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Women 350
_ A
9
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Group
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250
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Age (years) Fig. 2. Serum DHEA-S concentrations (_+SEM) vs. age in women. DHEA-S declines with age in both the TM and the comparison groups, and the TM-group values are higher in all age groups. TM-group values are characteristic of comparison-group women 5 to 10 years younger.
the comparison group for both men and women. Similar significance was found using nonlogarithmic, normalized data. For men, but not for women, there was also a significant interaction [F(10,1047) = 4.18, p -- .0001] between TM practice and age: TM practice had a significant effect only in older male age groups. A test of simple main effects for each male age group was significant (F>3) for the groups 35-39, 50-54, 60-64, 65-69, and 70+ (p < .05). All four of the significant or near-significant simple main effects for men over 40 were in the direction of TM participants having higher values. Simple main effects were not determined for women since an interaction was not observed. In all 11 of the measured age groups in women, the mean DHEA-S levels of the TM group were higher than for the nonmeditators. There were several variables recorded from the TM-group subjects that differed from the norm and that conceivably could account for the observed differences in DHEA-S levels. A high proportion of subjects, mostly from the younger age groups, was vegetarian (40% of women and 59% of men). In women, there was no correlation between meat consumption and DHEA-S elevation (r = -.009). In men, meat consumption was positively correlated with DHEA-S elevations (r = .20). This was attributed to the fact that nonvegetarians were predominantly in age groups over 40,
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the only male groups in which DHEA-S elevations were observed. Similarly, exercise and indices of obesity (body mass index and deviation from ideal weight) were not correlated with DHEA-S elevation (r < .15 for all values). Because so few TM subjects used tobacco or alcohol, it was not possible to analyze these factors as contributing variables. Although 49% of the male and 55% of the female members of the TM group were former smokers, and 32% of the men and 29% of the women were smoking at the time of instruction in TM, only 0.7% of the men and 1.9% of the women still smoked at the time of the study. This is probably considerably different from the nonmeditators, for whom data on smoking activity were not collected. In the population at large, for similar age groups, the incidence of smoking was 37% for men and 28% for women (National Center for Health Statistics, 1985). Similarly, only 9% of TM practitioners consumed any alcohol.
DISCUSSION The data presented here reveal that men over 45 and women of all age groups, who are experienced practitioners of the TM and TM-Sidhi programs, have serum DHEA-S concentrations that are higher than those found in a healthy, normal, nonmeditating population consulting dermatologists for cosmetic reasons and reported previously by the same laboratory. Two important questions must be addressed: first, whether the comparison between groups is valid; and second, whether these findings are the result of regular practice of the TM program or whether they reflect another characteristic of the TM group or some other experimental effect. It is unlikely that the observed differences are due to the selection of the comparison population. Comparison subjects represented healthy clients who visited a cosmetic surgery/dermatology practice, but these values are probably representative of North American values in general. Virtually identical data for each age grouping were obtained from 517 normal female participants in a multiphasic health screening program of the (Kaiser) Permanente Medical Group, Oakland, CA (Orentreich et al., 1984) and from 98 normal male participants in the Baltimore Longitudinal Study on Aging (Orentreich et al., manuscript in preparation). Although the TM-group subjects were different from normal populations in their reduced consumption of tobacco, alcohol, and meat, as noted above, as well as of prescribed and nonprescribed drugs, the observed results could not be attributed to any of these factors. Analysis indicated that vegetarianism did not make a systematic contribution to the elevated mean DHEA-S levels. This conclusion is supported by the findings of
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Schultz and Keklem (1983), who measured DHEA-S of 159 _+ 65 Bg/dl in vegetarian women (mean age, 32.6) vs. 176 + 48 ~tg/dl in nonvegetarians (mean age, 32.0), and by H/im/il/iinen et al. (1984) who did not observe any change in DHEA-S in 30 men transferred from a diet high in saturated fat and animal protein to an experimental diet consisting mostly of fruit, vegetables, vegetable oils, and fish. In addition, Hill et al. (1977) did not observe any change in D H E A levels in four female nurses who were switched to a low-fat vegetarian diet. It is also improbable that the lack of smokers in the TM group contributed to the differences, since cigarette smoking has been found to increase DHEA-S as well as androstenedione levels in both women (Khaw et al, 1988) and men (Barrett-Connor and Khaw, 1987). These findings appear, at first, to be paradoxical and to cast doubt on the validity of DHEA-S as a marker of aging. However, it is known that the human lung has considerable capacity to metabolize DHEA-S, both to other sulfoconjugates (Menzel et al., 1970) and to unconjugated steroids (Milewich et al., 1983), and to metabolize androstenedione (Milewich et al., 1977). Consequently, cigarette smoking may impair normal pulmonary clearance of adrenal androgens, a finding which has been demonstrated in the rat (Hartiala et al., 1978). Thus, any aging study in which the test population has compromised pulmonary function relative to a healthy population, including exposure to tobacco smoke, could not rely on DHEA-S as an aging marker. In the present study, the strong likelihood of a higher smoking incidence in the comparison group (though not measured) than in the meditators might simply raise the "noise" level of DHEA-S in the comparison group and mask DHEA-S elevations in the TM group due to other factors. We are not aware of any studies indicating an influence of alcohol on DHEA-S. We could also not explain any difference in the two populations from the sampling methods. The DHEA-S levels used for the comparison group norms were assayed under identical conditions in the same laboratory. Although assaying of meditator sera continued 3 years longer than the comparison group, many assays were contemporaneous. DHEA-S, unlike D H E A and other androgens, is secreted into a large plasma pool with a half-life of 10-20 hr and, therefore, does not display large circadian or ultradian rhythmic fluctuations (Rosenfeld et al., 1975). Several recent studies, however, have shown small but significant circadian rhythms in plasma DHEA-S by cosinor analysis in young (but not old) men (Del-Ponte et al., 1990; Montanini et al., 1988) and women (Carandente et al., 1990). These studies are remarkable for the strong agreement among them: all showed amplitudes of 11-15% of the mesor and an acrophase between approximately 2:00 and 4:00 PM for subjects of younger ages (21-23 years). While the lack of rhythmicity in the older men would rule out the timing of sampling as a source
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of bias in our older men, a small bias might be expected in the case of younger women, since the comparison group was randomly sampled throughout the workday. However, the amplitude of the circadian rhythm is in the same range as the variability of the DHEA-S assay itself and smaller than the daily variability (Orentreich et al., 1984). Moreover, DHEA-S remains at a broad plateau about the mesor through most of the workday hours following a 10:00 AM nadir (Carandente et al., 1990). Since the younger meditators were all sampled between 10:45 and 11:45 AM, any sampling bias due to circadian variation would tend to mask rather than exaggerate the observed elevations of DHEA-S in young female meditators. Sonka suggests that fasting may increase D H E A excretion (Sonka, 1976), but we are not aware of any postprandial changes in DHEA-S which could account for the elevated levels in the older group, who were sampled in the early afternoon. Similarly, no significant monthly, seasonal, or annual rhythms have been observed in men (Orentreich et al., 1984), and the 28% circatrigintan variation in DHEA-S observed with menses (Sinkl6si et al., 1984) would be expected to be distributed approximately uniformly across the subjects in both groups. One must finally consider whether the TM group represents a selfselected group that may have had other characteristics responsible for maintaining elevated levels of DHEA-S. If individuals who began TM tended to be healthier than the population at large, or if only the healthiest older meditators attended meditation conferences and volunteered for this study, then this may have provided a skewed sample of healthier individuals with a younger physiological age, who conceivably might have higher concentrations of DHEA-S. The same exclusion criteria were utilized for both TM and comparison groups. Since data have been published indicating that TM practitioners have lower health-care utilization (Orme-Johnson, 1978), TM subject recruitment was designed to avoid selection bias. Nevertheless, the possibility of selection bias remains an important confounder of these data that cannot be dismissed. This raises an important question that has not yet been sufficiently investigated: whether DHEA-S levels are related not only to age, but also to the general state of health, including the presence of chronic disorders, debility, stressors, and other life-style variables. If chronic disease and stress prove to be associated with subnormal DHEA-S levels, this could help explain our findings, because many of the physiological changes observed both during and outside the practice of the TM technique are opposite to those occurring in the acute and chronic adaption response to stressors: decreased plasma cortisol (Jevning et al., 1978), attenuated catecholamine production during exercise (Lang et al., 1979), increased 5-hydroxyindole3-acetic acid excretion (Bujatti and Riederer, 1976), reduced metabolism
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in resting forearm muscle and decreased blood lactate (Jevning et al., 1983a), and other physiological changes suggestive of decreased autonomic and metabolic activation (Wallace et al., 1983; Jevning et al., 1983b). The age-related decline in serum DHEA-S levels is probably due to reduced secretion by the adrenal cell, since nearly all DHEA-S production can be traced to the adrenal in both men and women, since DHEA-S is not stored in the adrenal cortex, and since its metabolic clearance rate declines slightly with age (Vermeulen, 1980; Laatikainen et al., 1971; Rivarola et al., 1967). This implies that some mechanism in the TM group is preventing the usual age-related reduction in those biochemical processes leading to delta-5 androgen production by the adrenal cell. If factors besides age, such as stress, general health, and other life-style variables, modify DHEA-S levels in normal individuals, then it would not be surprising that DHEA-S elevations were also found in younger TM groups. It is not clear why these elevations were found in younger women but not in younger men. Since TM practitioners have been shown to have an attenuated autonomic response to stressors (Orme-Johnson, 1973), the higher DHEA-S levels seen in the TM group may reflect protection against chronic overstimulation of the adrenal in response to stress. In support of this, Parker et al. (1985a,b) found reduced DHEA-S/cortisol ratios in patients under conditions of prolonged, severe illness and suggested that mineralocorticoid and adrenal androgen synthetic mechanisms may have been shifted to glucocorticoid production, which is essential to survival. The age-related decline in DHEA-S, which appears to be retarded in the TM group, may be due to decreased adrenal-cell responsiveness to ACTH (Pavlov et al., 1986) or some other factor, due to shunting to glucocorticoid pathways, or intrinsic to the adrenal cell. Since delta-5 androgens have been shown to be produced in primate brain, it is also conceivable that meditation may be altering neurosteroid production in the central nervous system (Robel et al., 1987). It is still unclear whether higher DHEA-S levels significantly contribute to longevity and improved health in older individuals or whether elevated D H E A - S levels simply reflect the lack of cumulative physical deterioration due to age, chronic stress, and illness. There are many reasons to suspect the latter in the difference between the two groups under study. Although comparisons of general health were not made in this particular study, the insurance study cited earlier (Orme-Johnson, 1987), showing reduced health-care utilization rates in TM practitioners, especially in the oldest groups studied, used a population of meditators including many from MIU and the surrounding community, implying that the meditators may indeed have been healthier. Since TM practice is a behavior that has been
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shown to modify numerous other physiological, psychological, and behavioral parameters, we doubt that the observed elevations in DHEA-S are primarily responsible for TM's effect on health utilization and other agerelated parameters.
ACKNOWLEDGMENTS
The authors gratefully acknowledge Clark T. Sawin, M.D., for his review of the manuscript and Kiavdia Chervinsky, Despina Marinescu, Kokila Patel, Bill Crosson, and Tom Moriarty for their skilled technical assistance.
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