Anorexia
Nervosa:
Search for Biological
Relevance
R. P. SPENCER Department USA
of Nuclear Medicine,
University
of Connecticut
Health Center, Farmington,
CT 06032,
Surnmary - Anorexia nervosa was explored as the possible expression of an aberration the processing of information which ordinarily has value in life protection or extension. Each of 6 areas was briefly reviewed, and noted to have the potential for failure to balance 2 or more factors. Anorexia nervosa may prove to be a psychiatric disorder in which there is altered handling of signals which otherwise are useful in survival/longevity.
1.
The most apparent advantage is a lower maintenance cost in terms of calories/day, for a smaller body size. This has to be balanced against 2 other considerations. A. A slightly larger body mass (‘storage calories’) might permit survival during a period of nearly absent caloric intake. B. Smaller body size has to be countered against the minimal mass required to carry out needed tasks. An aberration of the mechanisms to balance factors such as (A) and (B) might be a link to anorexia nervosa. 2. Anorexia nervosa is nearly exclusively a disorder of young women. The emaciated condition may contribute to a less ready acceptance of the sufferer by potential mates. Thus, marriage and mating can be delayed. At least in some species, nonbred females have a longer lifespan than their bred counterparts (1). 3 A variant on the above comment is that
Introduction Anorexia nervosa can be viewed in parallel with malabsorptive disorder as being what has been termed ‘starvation in the midst of plenty’. However, the ‘block’ in anorexia nervosa resides not in the gut mucosa, but in some part(s) of the central nervous system. Although psychological discussions of the disorder center on a refusal to follow the admonition to ‘eat’, and a distorted perception of body image, are there deeper biological roots? That is, can anorexia nervosal represent an aberration of mechanisms which otherwise may have survival/longevity advantages? Biological
background
The biological effects (and perhaps advantages) of a reduced body mass are numerous.
Date received Date accepted
of
11 August 1989 21 November 1989
19
20
MEDICAL HYPOTHESES
the incidence of ovulatory infertility in nulligravida women increases as the weight loss becomes more extreme. Women with a body weight (for their height) that is 85% or less than ‘ideal’, have a 4.7 fold increased risk of ovulatory infertility (2). Much of the defect might be related to a reduced fat mass and reduced storage of fat-soluble estrogens. Chong and coworkers (3) reported that administered human menopausal gonadotropin and human chorionic gonadotropin were as effective in patients lo-20% below body weight as in those of normal weight. That is, there was no end-organ failure. 4. If pregnancy and delivery, were to occur, what biological control was there over a second conception (prior to present techniques)? Breast feeding had been the only well-documented determinant of postpartum amenorrhea (4, 5). John has cited the sometime conflicting data on effects of nutritional status on waiting time to the next conception (5). Amenorrhea is induced by lactation and breast feeding. However, poor nutrition interferes with lactation; does this mean that ultimately, poor nutrition is an aid to a second pregnancy? Can the mixed biological signals be related to self-induced starvation? 5. Energy deprivation of cells has the effect of increasing the lethal effects of hyperthermia (Kim and coworkers have provided a summary of pertinent date (6)). Here again, we are faced with a compounding of ‘mixed messages’. Infection in the body (usually via the release of pyrogens) increases body temperature. Teleologically, this is a defense against infectious agents that are heat sensitive. The response may however, be destructive, since the energy deprived individual is putting her endogenous cells ‘at risk’. CounterbaIancing this is the known increased sensitivity of malignant cells to hyperthermia. Thus, energy deprivation, at a cellular level, can have multiple effects which may be producing conflicting signals.
6.
There is a considerable body of information confirming the fact that food deprivation increases the life span of biological species as diverse as spiders (7) and rats (8). Can these be endogenous signals that become misinterpreted, so that slight food deprivation progresses to marked undernutrition and death?
Discussion
Six areas have been briefly explored. Each of these might engender conflicting information in the central nervous system or even frank signals to reduce dietary intake. Thus, while anorexia nervosa is a psychiatric disease, it’s basis might be an aberration of the processing of information which has potential value in life protection or extension.
References I. Service, P. M.: The effect of mating status on lifespan.
2 3
4.
5. 6.
7. 8.
egg laying and starvation resistance in Drosophila melanogaster in relation to selection on longevity. J. Insect Phvsiol. 35: 447-452. 1989. Green.- B. B.; Weiss. N. S.; Daling, J. R.: Risk of ovulatory infertility in relation to body weight. Fertil. & Steril. 50: 721-726, 1988. Chong. A. P.; Rafael, R. W.; Forte, C. C.: influence of weight in the induction of ovulation with human menopausal gonadotropin and human chorionic gonadotropin. Fertil. & Steril. 46: 599-603, 1986. Jones, R. E.: A hazards model analysis of breastfeeding variables and maternal age on return to menses postpartum in rural Indonesian women. Human Biology 60: 853-871.1988. John, A. M.: Lactation and the waiting time to conception: an application of hazard models. Human Biology 60: 873-888,1988. Kim, J. H.: Kim, S. H.; Alfieri, A. A.: Selective killing of glucose-deprived hvpoxic cells bv hvperthermia. I. Protection b; purine ribonucleosiies.. ‘Radiat. Res. 116: 337-342.1988. Austad, S. N.: Life extension by dietary restriction in the bowl and doily spider, Frontinella pyramitela. Exper. Gerontol. 24: 83-92. 1989. Snyder, D. L. (ed): Dietary restriction and aging. Alan R. Liss, Inc. New York. 1988. pp. 335.
Nervosa:
Search for Biological
Relevance
R. P. SPENCER Department USA
of Nuclear Medicine,
University
of Connecticut
Health Center, Farmington,
CT 06032,
Surnmary - Anorexia nervosa was explored as the possible expression of an aberration the processing of information which ordinarily has value in life protection or extension. Each of 6 areas was briefly reviewed, and noted to have the potential for failure to balance 2 or more factors. Anorexia nervosa may prove to be a psychiatric disorder in which there is altered handling of signals which otherwise are useful in survival/longevity.
1.
The most apparent advantage is a lower maintenance cost in terms of calories/day, for a smaller body size. This has to be balanced against 2 other considerations. A. A slightly larger body mass (‘storage calories’) might permit survival during a period of nearly absent caloric intake. B. Smaller body size has to be countered against the minimal mass required to carry out needed tasks. An aberration of the mechanisms to balance factors such as (A) and (B) might be a link to anorexia nervosa. 2. Anorexia nervosa is nearly exclusively a disorder of young women. The emaciated condition may contribute to a less ready acceptance of the sufferer by potential mates. Thus, marriage and mating can be delayed. At least in some species, nonbred females have a longer lifespan than their bred counterparts (1). 3 A variant on the above comment is that
Introduction Anorexia nervosa can be viewed in parallel with malabsorptive disorder as being what has been termed ‘starvation in the midst of plenty’. However, the ‘block’ in anorexia nervosa resides not in the gut mucosa, but in some part(s) of the central nervous system. Although psychological discussions of the disorder center on a refusal to follow the admonition to ‘eat’, and a distorted perception of body image, are there deeper biological roots? That is, can anorexia nervosal represent an aberration of mechanisms which otherwise may have survival/longevity advantages? Biological
background
The biological effects (and perhaps advantages) of a reduced body mass are numerous.
Date received Date accepted
of
11 August 1989 21 November 1989
19
20
MEDICAL HYPOTHESES
the incidence of ovulatory infertility in nulligravida women increases as the weight loss becomes more extreme. Women with a body weight (for their height) that is 85% or less than ‘ideal’, have a 4.7 fold increased risk of ovulatory infertility (2). Much of the defect might be related to a reduced fat mass and reduced storage of fat-soluble estrogens. Chong and coworkers (3) reported that administered human menopausal gonadotropin and human chorionic gonadotropin were as effective in patients lo-20% below body weight as in those of normal weight. That is, there was no end-organ failure. 4. If pregnancy and delivery, were to occur, what biological control was there over a second conception (prior to present techniques)? Breast feeding had been the only well-documented determinant of postpartum amenorrhea (4, 5). John has cited the sometime conflicting data on effects of nutritional status on waiting time to the next conception (5). Amenorrhea is induced by lactation and breast feeding. However, poor nutrition interferes with lactation; does this mean that ultimately, poor nutrition is an aid to a second pregnancy? Can the mixed biological signals be related to self-induced starvation? 5. Energy deprivation of cells has the effect of increasing the lethal effects of hyperthermia (Kim and coworkers have provided a summary of pertinent date (6)). Here again, we are faced with a compounding of ‘mixed messages’. Infection in the body (usually via the release of pyrogens) increases body temperature. Teleologically, this is a defense against infectious agents that are heat sensitive. The response may however, be destructive, since the energy deprived individual is putting her endogenous cells ‘at risk’. CounterbaIancing this is the known increased sensitivity of malignant cells to hyperthermia. Thus, energy deprivation, at a cellular level, can have multiple effects which may be producing conflicting signals.
6.
There is a considerable body of information confirming the fact that food deprivation increases the life span of biological species as diverse as spiders (7) and rats (8). Can these be endogenous signals that become misinterpreted, so that slight food deprivation progresses to marked undernutrition and death?
Discussion
Six areas have been briefly explored. Each of these might engender conflicting information in the central nervous system or even frank signals to reduce dietary intake. Thus, while anorexia nervosa is a psychiatric disease, it’s basis might be an aberration of the processing of information which has potential value in life protection or extension.
References I. Service, P. M.: The effect of mating status on lifespan.
2 3
4.
5. 6.
7. 8.
egg laying and starvation resistance in Drosophila melanogaster in relation to selection on longevity. J. Insect Phvsiol. 35: 447-452. 1989. Green.- B. B.; Weiss. N. S.; Daling, J. R.: Risk of ovulatory infertility in relation to body weight. Fertil. & Steril. 50: 721-726, 1988. Chong. A. P.; Rafael, R. W.; Forte, C. C.: influence of weight in the induction of ovulation with human menopausal gonadotropin and human chorionic gonadotropin. Fertil. & Steril. 46: 599-603, 1986. Jones, R. E.: A hazards model analysis of breastfeeding variables and maternal age on return to menses postpartum in rural Indonesian women. Human Biology 60: 853-871.1988. John, A. M.: Lactation and the waiting time to conception: an application of hazard models. Human Biology 60: 873-888,1988. Kim, J. H.: Kim, S. H.; Alfieri, A. A.: Selective killing of glucose-deprived hvpoxic cells bv hvperthermia. I. Protection b; purine ribonucleosiies.. ‘Radiat. Res. 116: 337-342.1988. Austad, S. N.: Life extension by dietary restriction in the bowl and doily spider, Frontinella pyramitela. Exper. Gerontol. 24: 83-92. 1989. Snyder, D. L. (ed): Dietary restriction and aging. Alan R. Liss, Inc. New York. 1988. pp. 335.
