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Cholinergic REM Sleep Induction Test in Subjects at High Risk for Psychiatric Disorders Wolfgang Schreiber, Christoph Johannes Lauer, Klaus Krumrey, Florian Holsboer, and Jiirgen-Christian Krieg
The influence of the cholinergic agonist RS 86 on electroencephalographic (EEG) sleep was investigated in 21 healthy members of families identified as being at high risk for psychiatric disorders and in 17 healthy control subjects without any personal or family history of a psychiatric illness. In comparison to the placebo night, the administration of RS 86 led to a shortening of rapid eye movement (REM) latency in both groups. This effect, however, was much more pronounced in the high-risk group, whereas in the control subjects the arousal system and the slow-wave sleep during the first nonREM period were more affected. These observations suggest that the cholinergic action on sleep regulating mechanisms has differing preferential targets in high-risk probands and in control subjects.
Introduction Sleep lesearch in patients with an acute episode of a major depression has confirmed a variety cf all-night electroencephalographic (EEG) sJeep alterations, that is, frequent nocturnal awakenings, less slow-wave sleep (especially during the first nonREM period), a shortened rapid eye movement (REM) latency, an increase of REM sleep and an increased density of rapid eye movements during REM sleep (cf. Gillin et al 1984; Reynolds and Kupfer 1987; Lauer et al 1991). Several polysomnographic studies performed in remitted depressives dealt with the question of whether these alterations may--beyond reflecting only the acute state of the iilnessnserve as trait markers for depression. The results observed, however, are far from being conclusive: after the patients' recovery Knowles et al (1986) as well as Riemann and Berger (1989) observed an EEG sleep pattern almost indistinguishable from that in gender-matched and age-matched controls, whereas other investigators (Schulz et al 1979; Cartwright 1983; Rush et al 1986; Steiger et al 1989) reported a persistence of at least some of the aforementioned "depression-like" EEG sleep patterns in remission. Furthermore, Giles et al (1987) reported on an increased risk for relapse in those dep,'essed patients who displayed a short REM latency both in the acute and in the relam~d ~tate. Even if the findings of a "depression-like" EEG sleep in rer~i~sion may indicate a
From the Max Planck Institute of Psychiatry, Clinical Institute, Department of Psychiatry, Munich, Germany. Address reprint requests to Dr. W. Schreiber, Max Planck Institute of Psychiatry, Department of Psychiatry, Kraepelinstrasse 10, W-8000 Munich 40, Germany. Received August 8, 1991; revised February 18, 1992. @ 1992 Society of Biological Psychiatry
0006-3223/92/$05.00
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"trait"-vulnerability for an affective disorder (Cartwright 1983), a critical point, however, cannot be ruled out by these studies: the persisting polysomnographic alterations can represent neurobiological abnormalities that have been acquired during previous episodes and have therefore to be considered as "biological scars" (Holsboer 1989). One strategy to circumvent this uncertainty is to investigate the polysomnograms of healthy first-degree relatives of patients with an affective disorder. Up to now, investigations along this line have been rather scanty and most of the existing studies are limited by the fact that relatives with and without a personal history of a psychiatric disorder were intermingled (Giles et al 1988, 1991). In fact, there is only one study focusing on EEG-sleep in first-degree relatives with and without a personal history of depression (Giles et al 1989). Both samples, however, comprised only those subjects in whom a reduced REM latency had been previously observed. Therefore, it is hardly surprising that virtually no differences in EEG-sleep could be observed between these two groups. We have taken up and extended this approach by examining subjects who have no current and no lifetime diagnosis of a psychiatric disorder but whe due to their family history--are at high risk for developing one. In these high-risk probands we have assessed a variety of psychometric, neuroendocrine, and polysomnographic parameters, all known to be usually altered in depression, and first results have already been reported (Krieg et al 1990). The all-night EEG sleep in these high-risk probands tended to be shallower than that of the controls (i.e., decreased sleep efficiency index, more frequent nocturnal awakenings, and less slow-wave sleep). No differences, however, could be confirmed regarding various REM sleep parameters. We attributed this lack of REM sleep alterations to the relatively young age of our high-risk subjects as there is converging evidence that young depressives can hardly be distinguished from 'other psychiatric patients or normal controls by means of their REM latency or amount of REM sleep (cf. Appelboom-Fondu et al 1988; Kupfer et al 1989; Lauer et al 1990, 1991; Goetz et al 1991). A different situation emerges when a dynamic challenge test, such as the cholinergic REM sleep induction test (RIT), is applied. The RIT has been proven to consistently differentiate between depressed patients and healthy volunteers by inducing the onset of REM sleep significantly faster in depressed patients (cf. Sitaram et al 1984; Berger et al 1985, 1989; Gillin et al 1991). Moreover, the effects of the RIT on REM sleep, that is, on REM latency, have been demonstrated to be identical in young and elderly depressed patients, indicating that the REM sleep triggering mechanisms in young depressives are already disturbedmbut on a subthreshold level not yet affecting baseline EEG sleep (Lauer et ai 1987, 1990). In the present study we explored whether a similar subthreshold disturbance of REM sleep triggering mechanisms can be demonstrated in our high-risk probands by means of the cholinergic REM sleep induction test.
Methods
Subjects Our selection p~cedure for the "high-risk probands" has been previously described in full detail (Krieg et al 1990); thus, only a short description is presented here: The high-risk pmband is a first-degree relative of an inpatient ("index patient") with the DSM-III-R diagnosis of an affective disorder, that is, a major depression, a manic episode, or a bipolar disorder (APA i98~; verified by the Structured Clinical Interview for DSM-III-R; SCID; German version: Wittchen et a11990); all patients with the diagnosis
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Table 1. Distribution o f D S M - I I I - R Diagnoses in the Families Identified to be at H i g h Risk for Psychiatric Disorders
Index patients (n = 15) First-degree relatives (n = 15)
Major depression
Manic episode
Bipolar disorder
Schizophrenic disorder
n = 10
n = 1
n = 4
none
n = 12
none
n = 1
n = 2
of a dysthymia or a depressive disorder not otherwise specified (NOS) were excluded from the study. The index patient has to have at least one further first-degree relative with the diagnosis of an affective disorder, a schizophrenic or schizoaffective disorder or an anxiety disorder (verified by the SCID) in order to ensure the a,,mpling of families highly loaded with psychiatric d~sorders. It has to be guaranteed that the high-risk proband is not suffering from either a current or lifetime DSM-III-R diagnosis of a psychiatric disorder (including dysthymia or depress~;on NOS; verified by the SCID). The cholinergic REM induction test (RIT) was performed with 1.5 mg RS 86 in 21 high-risk probands (HRP; 9 women, 12 men) from 15 different families; 10 families provided 1 HRP, 4 families 2 HRP, and 1 family 3 HRP. The distribution of DSM-IIIR diagnoses in these families is presented in Table 1. Seventeen healthy volunteers (from 17 different families) served as control subjects (CP; 9 women, 8 men). They were carefully screened to exclude any personal (using the SCID) or family (semistructured interview) history of psychiatric disorders. In case of doubt, the respective relatives of the CP were contacted personally to reconfirm the complete absence of psychiatric disorders in their families. All pm~icipants under investigation had been free of any prescription or nonprescription drug (including salicylates or antihistamines) for over 3 months. On the 2 days preceding the EEG sleep registration, no intake of caffeine (apart from a cup of coffee in the morning) or alcohol was allowed. The absence of insomnia, sleep apnea, or periodic leg movements was confirmed by clinical exploration and by the visual inspection of the polysomnograms of the placebo night. In case of doubt, exclusion from the study was fixed in the protocol. During the 2 weeks preceding the polysomnographic examination, both the HRP and the CP were instructed to go to bed between 10:30 PM and 11:30 PM in order to habituate to the "lights off" time as prescribed in the study protocol. They also had to fill in a sleep log during this time span. The tolerated latitude in deviation from the requested "lights off" time was about 30 min and controlled by the sleep log and a personal interview. Prior to the onset of the investigation, an extensive physical examination including electrocardiogram (EKCJ), blood analysis, and urinary drug monitoring was carried out. The study protocol was accepted by an ethics committee and written informed consent was obtained from all participants. All subjects under investigation were paid for their participation.
REM Sleep Induction Test (RIT) For the RIT, the spiropiperidyl derivate RS 86 was used, which is a direct, orally acting muscarinic agonist with a plasma half-life of 6-8 hr (P Bevan, unpublished data, 1981; Spiegel 1984; Palacios et al 1986). If any, only minor side effects have been reported
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after the intake of 1.5 mg RS 86 (Krieg et al 1987)--the dosage chosen for this investigation. After 1 night of habituation to the experimental setting, placebo or 1.5 mg RS 86, respectively were administered at 10:00 PM of nights 2 and 3. All subjects were blinded to the placebo-drag regimen. In the majority of the participants (76% of the high-risk probands and 65% of the control subjects) a placebo-RS 86 order was applied. Although Berger et al (1989) demonstrated the absence of both "time-serial" effects (placebo-RS 86 regimen) and "carry-over" effects (RS 86-placebo regimen) in a recent study applying the identical design, we chose an RS 86-placebo regimen in a subgroup of our participants in order to control for such possible order effects. Sleep was recorded from "lights off" (11:00 PM) until "lights on" (7:00 AM) using standard procedures: electroencephalogram (EEG; C3-A2, C4-Am), horizontal electrooculogram (EOG), and submental electromyogram. Records were visually scored according to standard criteria (Rechtschaffen and Kales 1968). In addition to the EEG sleep parameters usually determined (for definitions see Lauer et ai 1991), the following variables were calculated for the first and the second sleep cycle: the relative amount of time awake and of slow-wave sleep per nonREM period, the duration of the nonREM period, and REM period, respectively, and the length of the sleep cycle. All calculations were performed with a computerized program (Pollmiicher and Lauer 1992). Statistical analysis was carried out by a repeated measures m~zltivariate analysis of variance (MANOVA) with group (HRP versus CP) as between-subjects factor and trial (placebo versus RS 86) as within-subjects factor. In case of significant main effects for group or for trial, univariate F-tests were used in order to identify those EEG-sleep variables, which contribute to the overall group or trial differences. After determining such variables, their subeffects on group differences within each trial or on trial differences within each group were analyzed over parameter estimates for contrasts using the Student's t-test for independent or related samples, respectively. Due to multiple ,.~omparisons, the level of significance, which initially was set at 5%, was adjusted (Bonferroni procedure) in order to control for Type I enor.
Results Age-distribution and gender-distribution were similar between the HRP and the CP [age: T(I) - 0.37; gender: X2(I) - 0.08l. Application of the repeated measures multivariate analysis of variance resulted in significant main group- and trial-effects, but no significant intera,:~ion effects were observed [Wiiks multivariate tests of significance; effect of group: approximately F(I 8,27) = 2.28, p < 0.05; effect of trial: approximately F(18,27) - 2.66, p < 0.05l. Group means and SD of the EEG sleep variables considered in the analysis are summarized in Table 2 for both the placebo and the RS 86 night. Table 3 gives the results of the univariate F-tests within MANOVA; significant variable effects on the group or on the trial differences are indicated by an asterix (*). The significant main group effect was due to the amount of REM sleep, which was increased in the HRP [pooled over trials mean -+ SD: 22.6 ± 3.0 (~ g~'Tj versus 19.3 _.+ 4.0 (% SPT)] and to the REM density index of the second REM period, which was decreased in the HRP (pooled over taials mean _+ SD: 1.65 _~ 0.60 versus 2.16 +_ 0.92). The following variables contribute J to the significant main trial effect: the slow-wave
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Table 2. Effects of 1.5 mg RS 86 on EEG Sleep Vmiables in 21 High-Risk Probands and in 17 Control Probands High-risk probands EEG sleep parameters Sleep period time (min) Sleep efficiency index (%) Sleep onset latency (min) Slow-wave sleep latency (min) Number of awakenings Intermittent time awake (min) REM latency (lights off) (min) REM latency (sleep onse0 (min) Slow-wave sleep (% SFr) REM sleep (% SPT) Ist Sleep cycle REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density 2nd Sleep cycle NonREM period duration (min) REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density
Placebo night
RS 86 night
436.1 88.3 31.3 17.2 13.6 24.8 113.9 82.6 12.6 20.8
± ± ± ± _ ± ± ± ± ±
39.9 10.6 38.8 7.9 6.9 19.6 64.3 37.9 6.6 4.2
440.3 90.2 21.9 28.8 13.2 15.2 78.8 57.0 9.6 24.5
± ± ± ± ± ± ± ± ±
16.9 3.9 11.6 28.9 6.3 10.3 29.6 30.2 7.0 4.7
18.2 6.4 32.5 1.6
± ± ±
12.7 10.7 19.7 1.1
21.1 3.7 24.6 1.5
± ± ± ±
17.0 5.6 22.3 I.I
83.3 25.5 5.7 24.5 1.7
± ± ± ± ±
19.9 15.2 9.2 18.1 0.8
70.6 20.0 4.0 20.8 1.6
± ± ± ± ±
11.2 10.5 5.0 19.7 0.7
Control probands Sleep period time (min) Sleep efficiency index (%) Sleep onset latency (min) Slow-wave sleep latency (min) Number of awakenings Intermittent time awake (min) REM latency (lights off) (min) REM latency (sleep onset) (min) Slow-wave sleep (% SPT) REM sleep (% sp'r) i st Sleep cycle REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP~ REM density 2nd Sleep cycle NonREM period duration (min) REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density
430.7 88.5 25.3 19.3 I1.1 25.0 107.5 82.2 11.6 18.2
± ± ± ± ± ± ± ± --.
20.3 7.6 15.3 11.6 6.8 26.5 36.4 30.9 6.9 4.5
425.2 87.6 22.9 40.9 !i.2 25.5 93.2 70.2 9.1 20.5
± ± ± ± ± ± ± ± ± ±
28.3 6.9 10.7 44.6 9.0 22.1 38.6 35.0 5.7 5.5
16.4 2.6 33.7 !.7
± ± ± ±
12.1 4.6 22.6 0.6
17.7 9.6 21.9 !.4
± ± ± ±
12.0 15.8 24.2 1.0
84.3 25.3 5.0 17.1 2.2
± ± ±
23.1 14.3 7.9 16.0 I.I
73.4 17.9 4.5 21.7 2.1
--± ± ±
16.7 10.2 6.8 17.5 0.9
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Table 3. Results of the MANOVA Univariate F-tests in MANOVA Group
Trial
EEG sleep parameters
F(36,1)
Sleep period time (min) Sleep efficiency inde,~.(%) Sleep onset latency (rain) Slow-wave sleep latency (min) Number of awakenings Intermittent time awake (min) REM latency (lights off) (min) REM latency (sleep onset) (min) Slow-wave sleep (% SPT) REM sleep (% SPT) 1st Sleep cycle REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density 2nd Sleep cycle NonREM period duration (min) REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density
1.7,, 0.96 0.19 1.06 !.33 1.22 0. I I 0.43 0.05 8.43
9.02 14.06 6.79 8.23
0.57 0.17 0.02
0.52 !.10 5.36
0.00
0.50
0.28 0.19 0,00 0.30
6.66 4.02 0.57 0.11
4,35
p
F(36,1) 0.03 0.37 1.45
9.64 0.01 1.03
*
!.26
*Indicates the variablesthat contribute significantlyto main group or trial effects.
sleep latency, which increased remarkably in the RS 86 night (pooled over groups mean ± SD: 18.2 ± 7.0 versus 34.85 ± 26.5); the slow-wave sleep (SWS) during the first nonREM period as well as during the total night, the relative amounts of which decreased after the administration of 1.5 mg RS 86 [pooled over groups mean + SD: 12.1 +_ 4.7 versus 9.35 ± 4.5 (% 1st nonREMP); 33.1 ± 14.9 versus 23.2 _ 16.4 (% SPT)]; the REM latency measurements (either from "lights off" or from "sleep onset"), which were shortened in the RS 86 night [pooled over groups mean ~: SD: 110.7 ± 24.4 min versus 86.0 _ 24.32 min ("lights off'); 82.4 ± 24.4 min versus 63.6 ± 23.1 min ("sleep onset")], and the amount of REM sleep, which was increased in the RS 86 night (pooled over groups mean _+ SD: 19.5 _ 3.0 % SP'I" versus 22.5 _ 3.6 % SPT). Furthermore, the duration of the second nonREM period was shortened in the drug night (pooled over groups mean ± SD: 83.8 _+ 15.24 min versus 72.0 ± 10.0 min). There was no influence of RS 86 on sleep continuity indices or on REM density measurements. The subeffects for the EEG sleep variables, which contrib~ted significantly to the group and trial differences are summarized in Table 4. During the placebo night, neither REM sleep nor REM density differed significantly between the two groups. During the RS 86 night, the HRP showed a significantly increased amount of REM sleep and their REM density index of the second REM period was decreased compared to the CP.
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Table 4. Subeffects of the Variables Contributing Significantly to Main Group or Trial Effects Placebo night (HRP vs CP) Slow-wave sleep latency REM latency (lights off) REM latency (sleep onset) Slow-wave sleep REM sleep I st Sleep cycle Slow-wave sleep 2nd Sleep cycle NonREM period duration REM density
NS
NS
RS 86 night (HRP vs CP)
HRP (placebo vs RS 86 night)
CP (placebo vs RS 86 night)
*
NS • • • •
* NS NS NS NS
NS
*
NS
*
*
*Indicates significant differences; NS, not significant.
Comparing the placebo and the RS 86 night within the HRP and the CP separately, it was found that the CP showed a two-fold lengthening of the SWS latency and a decrease of the amount of SWS during the first nonR~M period. In the HRP, neither of these two EEG sleep parameters was significant!y affected by RS 86. Regarding REM latency, a significant shortening was observed in the HRP, but not in the CP (Figure 1). In more detail: whereas during the placebo night none of the subjects under investigation displayed a sleep onset REM period (SOREMP; REM latency < 25 rain), after the challenge with RS 86 this was the case in 3 (14%) HRP but in none of the CP. These differing frequencies of SOREMPs approximated the level of significance (X2[1] = 2.64, p < 0.10). The amount of REM sleep was significantly increased in the HRP, but not altered in the CP. Regarding the effects of RS 86 on the second sleep cycle, a significant shortening of the second nonREM period (= latency of the second REM period) was found in the HRP but not in the CP. Finally, since some subjects did not receive a placebo-RS 86 regimen but the inverse one, the EEG sleep parameters of the placebo night 2 (HRP: n = 16; CP: n = 11) and of the placebo night 3 (HRP: n = 5; CP: n = 6) were compared within the HRP and the CP, respectively. In agreement with the findings of Berger et al (1989), no differences were obtained. The same held true for the within-group comparisons of RS 86 night 3 and the RS 86 night 2. Discussion
The present study is the first to investigate the effects of a cholinomimetic on the EEG sleep pattern in a pure sample consisting of probands who as yet have not suffered from a psychiatric disorder, but who, due to their family history, run a high risk for developing onc.
Indeed, Sitaram et al (1987) investigated the effects of a cholinergic challenge on EEG sleep in subjects at high risk for psychiatric disorders. Using the arecoline-paradigm, the authors reported a more pronounced REM sleep-inducing effect in their high-risk probands than i~, 'heir control subjects. However, these observations are limited by the fact that higL-iisk probands with and without a personal history of a psychiatric disorder were
86
W. Schreiber et al
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rain
HRP
CP
p < o.ool
N.S.
q
160 -
P \
I I
\ 'e
140 -
\
\I \t,
120 -
/Y"~")~3
0,//i/`"
100
"o
8o
Figure !. Effect of RS 86 on REM Latency (Min from Sleep Onset) in 21 High-Risk Probands (HRP) and in 17 Control Subjects (CP).
60
40
20
PLACEBO
RS86
PLACEBO
RS86
intermingled, In contrast, our sample was restricted to only those probands who had not such a personal history but who are members of families that, in most cases, were highly loaded with affective disorders; this certainly provides a "pure" sample in this regard. Using this strategy, we tried to reduce the frequency of a false-positive identification of subjects at high risk (cL Krieg et al 1990). However, one has to keep in mind thatwlike in all other studies performed on high-risk probands--only a certain percentage of our HRP are genetically determined to be vulnerable for a psychiatric disorder. In a recent review of twin studies, McGuffin and Katz (1986) concluded that only about 20%-30% of healthy pedigrees of families highly loaded with psychiatric disorders are at "true" risk. Before discussing the results of the present study, one methodological aspect requires some comment: we are aware that our observations may be biased by the fact that in five of our families more than one high-risk proband was investigated. This cot~ld give rise to the critique that a possible genetically determined impact on the EEG sleep pattern could result in an overestimation or underestimation ef at least some of the effects observed in the present report. Up to now, there have only been a few studies dealing with the issue of genetic influences on EEG sleep (Webb and Campbell 1983, Hori 1986, Linkowski et al 1989, 1991). Taken together, a moderate concordance only among identical twins concerning REM sleep--the major focus of this studymhas to be assumed. This concordance, however, was found to be absent when looking at fraternal twins, whose genetic loa0 corresponds to the one of our HRP.
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During the placebo nighL no major difference between HRP and CP became evident. This finding is not consistent with our earlier report, in which the EEG sleep of the HRP was, in general, characterized by a decreased sleep quality (Krieg et al 1990). However, the subjects of the present study sample are not identical to those reported on earlier. Therefore, differing rates of subjects at "true" risk for psychiatric disorders may account for these inconsistencies. In this respect, one also has to consider how prominent a "premorbid marker" must be to be biostatistically confirmed in a group in which only 20%-30% of the subjects investigated are at "true" risk (Krieg et al 1990). The effects of 1.5 mg RS 86 on the EEG sleep pattern indicate rather different, preferential target sites of the cholinergic action on sleep regulating mechanisms in the HRP and in the CP: In the HRP the mean latencies of both the first and the second REM period were distinctly shorter in the drug night than in the placebo night. This finding is consistent with the above-mentionod report of Sitaram et al (1987). Furthermore, whereas none of our HRP had a spontaneous sleep onset REM period (SOREMP) in the placebo night, three of them (all were members of different families) displayed such a rapid onset of REM sleep after the application of RS 86. After a cholinergic challenge, such SOREMPs are reported to occur frequently in patients with a major depression but seem to be nearly completely absent in healthy subjects and in patients with other psychiatric disorders (i.e., anxiety disinters and eating disorde.rs; Berger et al 1985, 1989; Lauer et al 1988, 1990; Riemann et al 1990). Therefore, based on the observations of both an advanced onset of REM sleep and the increased occunence of SOREMPs, a subthreshold disturbance of the REM sleep-regulating systems, which appears to be comparable to that reported in young depressives (Lauer et al 1987, 1990), can be assumed in the HRP. On the other hand, signs of an increased arousal and/or an impaired slow-wave sleep were not present during the first nonREM period in the HRP. These findings suggest that REM sleeppromoting systems are the preferential target of RS 86 action in the HRP. Unfortunately, an estimation as to what extent a similar preferential target of cholinergic action, that is, of RS 86, is present in patients with a major depression cannot be made, since none of the respective studies has focused in detail on the EEG sleep parameters of the first nonREM period. In contrast, in the control subjects RS 86 caused a minor shortening of the first REM latency and induced effects that were mainly directed on the composition of the first nonREM period. These effects can best be characterized as a flattening of the quality of sleep (e.g., an increase of wake time, a two-fold prolongation of slow-wave sleep l~tency, and a one-third reduction of slow-wave sleep during this nonREM period). Thus, the administration of RS 86 resulted in an increased arousal paralleled by an impairment of slow-wave sleep. These findings are in line with studies performed in animals (rats and rabbits, respectively) and in humans (P Bevan, unpublished data, 1981; Spiegel 1984; Berkowitz et al 1990). Therefore, we assume that in our CP the preferential target of action of RS 86 is the weakening of the inhibitory function of nonREM sleep in both the arousal system and the REM sleep-promoting system, which, in part, was hypothesized by Kupfer et al (1984) and by Feinberg et al (1988). With regard to the mechanism of the RIT, Gillin et al (1979) proposed a direct action of cholinomimetics on muscarinic receptors of sleep-regulating neurons with the consequence of an earlier onset of REM sleep after a cholinergic challenge. In depression, these authors assumed an up-regulation of these muscarinic receptors to be responsible for the rapid onset of REM sleep (Gillin et al 1979). Therefore, a similar "depressionlike" up-regulation of muscarinic receptors might be postulated for (some of) our HRP
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but not for our CP. However, the hypothesis of an up-regulation of muscarinic receptors has been questioned by recent studies. Gillin et al (1991) failed to induce a shortening of REM latency when administering oxtremorine, a potent muscarinic agonist, to a strain of rats with an increased muscarinic receptor density in the brain. In addition, Riemann et al (1991) were not able to induce the depression-like early onset of REM sleep by a cholinergic challenge in healthy subjects who were pretreated with scopolamine in order to achieve muscari_nic receptor supersensitivity. Therefore, the induction of REM sleep may rather be related to an impaired REM-suppressive monoaminergic influence (Gillin et al 1982; Riemann et al 1991). Finally, reducing sleep regulation to a mere central cholinergic/aminergic interaction would neglect the involvement of other neurotransmitters and neuropeptides. For example, although the hermones of the iimbic-hypothalamicpituitary-adrenocortical (LHPA) axis do not appear to be directly involved in the regulation of REM sleep, they seem to act on nonREM sleep regulation (cf Holsboer et al 1988; Born et al 1989). In addition, the stimulatory effect of central cholinergic pathways on the LHPA system is well documented (e.g., Steiner and Grahame-Smith 1980). A pm,sible involvement of the LHPA axis in sleep regulatory processes is also of spe~:ial interest to us, because we could demonstrate that in a certain percentage of our HRP the feedback mechanisms of the LPHA axis regulating the secretory activity of its hormones are impaired in a similar manner as in depressed patients (Krieg et al 1991). To summarize our observations, by performing the REM sleep-induction test with 1.5 mg of the cholinergic agonist RS 86 in subjects at high risk for psychiatric disorders and in healthy volunteers not at risk, we found good evidence for (a) preferential targets of cholinergic action differing between subjects at high risk and control subjects and (b) a subthreshold disturbance of REM sleep-promoting systems in our high-risk probands. We are very grateful to A. Yassouridis, PhD, for his expert statistical assistance.
References American Psychiatric Association t 1987): Diagnostic and Statistical Manual of Mental Disorders, 3rd ed rev, Washington, DC: American Psychiatric Press. Appelboom-Fondu J, Kerkhofs M, Mendlewicz J (1988): Depression in adolescents and young adults--polysomnographic and neuroendocrine aspects. J Affective Disord 14:35-40. Berger M, H6chli D, Zulley J, Lauer C, yon Zerssen D (1985): Choiinomimetic drug RS 86, REM sleep, and depression. Lancet i: 1385-1386. Berger M, Riemann D, H6chli D, Spiegd R (1989): The cholinergic rapid eye movement sleep induction test with RS 86: State or trait marker of depression. Arch Gen Psychiatry 46:421428. Berkowitz A, Sutton L, Janowsky DS, Gillin JC (1990): Pilocarpine, an orally active muscarinic cholinergic agonist, induces REM sleep and reduces delta sleep in normal volunteers. Psychiatry Res 33:113-119. Born J, Sp.;ith-Schwaibe E, Sehwakcnhofer H, Kern W, Fehm HL (1989): Influences of corticotropin-releasing hormone, adrenocorticotropin, and cortisol on ,,deep in normal man. J Clin Endocrinol Metab 68:904-91 l. Cartwright RD (1983): Rapid eye movement sleep characteristics during and after mood-disturbing events. Arch Gen Psychiatry 40:197-201. Feinberg 1, Baker T, Leder R, March D (1988): Response of delta (0-3 Hz) EEG and eye movement density with 100 minutes of sleep. Sleep I 1:473-487.
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Giles DE, Jarrett RB, Roffwarg HP, Rush AJ (1987): Keduced rapid eye movement latency: A predictor of reoccurrence in depression. Neuropsychop~armacology 1:33-39. Giles DE, Biggs MM, Rush AJ, Roffwarg HP (1988): Risk ~iactorsm families of unipolar depression. I. Incidence of illness and reduced REM latency. J A~.!"ectiveDisord 14:51-59. Giles DE, Kupfer DJ, Roffwarg HP, Rush AJ, Biggs MM, Etzel BA (1989): Polysomnographic parameters in first-degree relatives of unipolar probands. Psychiatry Res 27:127-136. Giles DE, Roffwarg HP, Kupfer DJ (1991): Abnormal EBG sleep in children: a hypothesis. Biol Psychiatry 29:180 A. Gillin JC, Sitaram N, Duncan WC (1979): Muscarinic supersensitivity: A possible model for the sleep disturbance of primary depression? Psychiatry Res 1:17-22. GiUin JC, Sitaram N, Mendelson WB (1982): Acetylcholine, sleep and depression. Hum Neurobiol 1:211-219. Gillin JC, Sitaram N, Wehr T, et al (1984): Sleep and affective illness. In Post RM, Ballenger JC (eds), Neurobiolosy of Mood Disorders. Baltimore: Williams & Wilkins, pp 157-189. Gillin JC, Sutton L, Ruiz C, et al (1991): The cholinergic rapid eye movement induction test with arecoline in depression. Arch Oen Psychiatry 48:264-270. Goetz RR, Puig-Antich .l, Dahl RE, et al (1991): EEG sleep of you~lgadults with major depression: A controlled study. J Affective Disord 22:91-100. Holsboer F (1989): Psychiatric implications of altered limbic-hyl~thalamic-pituitary-adrenocortical activity. Fur Arch Psychit~try Neurol Sci 238:302-322. Holsboer F, yon Baerdeleben U, Steiger A (1988): Effects of ir~travenous corticotropin-rele~sing hormone upon sleep-related growth hormone surge and sleep EBG in man. Neuroendoc,,inology 48:32-38. Hori A (1986): Sleep characteristics in twins. Jpn J Psychiatry l~o.urol 40:35-46. Knowles JB, Cairns J, MacLean AW, et al (1986): The sleep t~f remitted bipolar depres~dves: Comparison with sex and age-matched controls. Can J Psych~a~try31:295-299. Krieg JC, Bossert S, Pirke KM, von Zerssen D, Berger M (1987): 'the influence of the mus¢:arinic agonist RS 86 on the cortisol system. Biol Psychiatry 22:573-582. Krieg JC, Lauer CJ, Hermle L, yon Bardeleben U, Polimacher T, H¢,lsboerF ( 1990): Psychometric, polysomnographic, and neuroendocrine measures in subjects al: high risk for psychiatric disorders: Prelimin~uy results. Neuropsychobiology 23:57-67. Krieg JC, Lauer CJ, Schreiber W, Holsboer F (1991): NeuroeL~ocrine and polysomnographic findings in subjects at high risk for psychiatric disorders. Biol Psychiatry 29, 1IS: 60. Kupfer DJ, Ulrich RF, Coble PA, et al (1984): Application of a~tomated REM and slow wave sleep analysis: ll. Testing the assumptions of the two-proce,'s-~odel of sleep regulation in normal and depressed subjects. Psychiatry Res 13:335-343. Kupfer DJ, Frank E, Ehlers CL (1989): BEG sleep it. young de,?ressives: First and second night effects. 8iol Psychiatry 25:87-97. Lauer CJ, Riemann D, Berger M (1987): Age, REM sleep and depression. Sleep Res 16:283. Lauer CJ, Zulley J, Krieg JC, Riemann D, Berger M (1988): EBC sleep and the cholinergic REM induction test in anorexic and bulimic patients. Psychiatry Re,~ 26:171-18 I. Lauer CJ, Krieg JC, Riemann D, Zulley J, Berger M (i990): A p~lysomnographic study in young psychiatric inpatients: Major depression, anorexia nervosa, bulimia nervosa. J Affective Disord 18:235-245. Lauer CJ, Riemann D, Wiegand M, Berger M (1991): From early to late adulthood: changes in BEG sleep of depressed patients and healthy volunteers. Biol Psychiatry 29:979-993. Linkowski P, Kerkhofs M, Hauspie R, Susanne C, Mendlewicz ! (1989): EEG sleep patterns in man: a twin study. Electroencephalogr Clin Neurophysiol 73:279-284. Linkowski P, Kerkhofs M, Hauspie R, Mendlewicz J (1991): A genetic study in twins I~vingapart. Eiectroencephalogr Clin Neurophysiol 79:114-118.
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McGuffin P, Katz R (1986): Nature, nurture and affective disorder. In Deakin JFW (ed), The Biology of Affective Disorders. London: Gaskell Press. Palacios JB, Bolliger G, Closse A, Enz A, Gmelin G, Malanowski J (1986): The pharmacological assessment of RS 86 (2-ethyl-8-methyl-2,8-diazaspiro[4,5]-decan-l,3-dionhydrobromide). A potent, specific muscarinic acetylcholine receptor agonist. Eur J Pharmacol 125:45-64. Pollm[icher T, Lauer CJ (1992): Physiologic yon Schlaf und Schlafregulation. In: Berger M (ed), Handbuch des normalen und gest/Srten Schlafs. Berlin, Heidelberg, New York: Springer, pp 144. Rechtschaffen A, Kales A (1968): A Manual of Standardized Terminology, Techniques and Scoring System for Sleep Stages of Human Subjects. Washington, DC: National Institute of Health Publications, US Government Printing Office. Reynolds CF, Kupfer DJ (1987): Sleep research i~n.affeetivc-i!!ne~s:-~ate~f t~-.art ¢i.r~-!987,. Sleep 10:199-215. Riemann D, Berger M (1989): EEU sleep in depression and in remission and the REM sleep response to the cholinergic agonist RS 86. Neuropsychopharmacology 2:145-152. Riemann D, Gann H, Hohagen F, Olbich R, Fleckenstein P, Berger M (1990): REM sleep in depression, anxiety disorders and schizophrenia. The influence of cholinergic stimulation with RS 86. In: JA Home (ed), Sleep '90. Bochum: Pontenagel Press, pp 235-237. Riemann D, Hohagen F, Fleckenstein P, Berger M (1991): The cholinergic REM-induction-test with RS 86 after scopolamine pretreatment in healthy subjects. Psychiatry Res 38:247-260. Rush AJ, Erman MK, Giles DE, et al. (1986): Polysomnographic findings in recently drug-free and clinically remitted depressed patients. Arch Gen Psychiatry 43:878-884. Schulz H, Lurid R, Cording C, Dirlich G (1979): Bimodal distribution of REM sleep latencies in depression. Biol Psychiatry 14:595--600, Sitaram N, Gillin JC, Bunney WE (1984): Cholinergic and catecholaminetgk receptor sensitivity in affective illness: Strategy and theory. In Post RM, Ballenger JC (eds), Neurobiology of Mood Disorders. Baltimore: Williams & Wilkins, pp 629--651. Sitaram N, Dube S, Keshavan M, Davies A, Reynal P (1987): The association of supersensitive cholinergic REM-induction and affective illness with pedigrees. J Psychiatry Res 21:487-497. Spiegel R ( 1984): Effects of RS 86, an orally active cholinergic agonis~, on sleep in man. Psychiatry Res 11:1-13. Steiger A, yon Bardeleben U, Herth T, Holsboer F (1989): Sleep.EEG and nocturnal secretion of col~isol and human growth hormone in male patients with endogenous depression before treatmr~nt and after recovery. J Affective Disord 16:189-195. Steiner JA, Grahame-Smith DG (1980): Central pharmacological control of corticosterone secretion in the intact rat. Demonstration of cholinergic and serotonergic facilitatory and alpha-adrenergic inhibitory mechanisms. Psychopharmacology 71:213-217. Webb WB, Campbell SS (1983): Relationships in sleep characteristics of identical and fraternal twins. Arch Gen Psychiatry 40:1093-1095. Wittchen HU, Zaudig M, Schramm E, Spengler P, Mombour W, Klug J, Horn R (1990): SKID, Strukturiertes Klinisches Intera,iewfiir DSM-liI.R. Weinheim: Beltz-Verlag.
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Cholinergic REM Sleep Induction Test in Subjects at High Risk for Psychiatric Disorders Wolfgang Schreiber, Christoph Johannes Lauer, Klaus Krumrey, Florian Holsboer, and Jiirgen-Christian Krieg
The influence of the cholinergic agonist RS 86 on electroencephalographic (EEG) sleep was investigated in 21 healthy members of families identified as being at high risk for psychiatric disorders and in 17 healthy control subjects without any personal or family history of a psychiatric illness. In comparison to the placebo night, the administration of RS 86 led to a shortening of rapid eye movement (REM) latency in both groups. This effect, however, was much more pronounced in the high-risk group, whereas in the control subjects the arousal system and the slow-wave sleep during the first nonREM period were more affected. These observations suggest that the cholinergic action on sleep regulating mechanisms has differing preferential targets in high-risk probands and in control subjects.
Introduction Sleep lesearch in patients with an acute episode of a major depression has confirmed a variety cf all-night electroencephalographic (EEG) sJeep alterations, that is, frequent nocturnal awakenings, less slow-wave sleep (especially during the first nonREM period), a shortened rapid eye movement (REM) latency, an increase of REM sleep and an increased density of rapid eye movements during REM sleep (cf. Gillin et al 1984; Reynolds and Kupfer 1987; Lauer et al 1991). Several polysomnographic studies performed in remitted depressives dealt with the question of whether these alterations may--beyond reflecting only the acute state of the iilnessnserve as trait markers for depression. The results observed, however, are far from being conclusive: after the patients' recovery Knowles et al (1986) as well as Riemann and Berger (1989) observed an EEG sleep pattern almost indistinguishable from that in gender-matched and age-matched controls, whereas other investigators (Schulz et al 1979; Cartwright 1983; Rush et al 1986; Steiger et al 1989) reported a persistence of at least some of the aforementioned "depression-like" EEG sleep patterns in remission. Furthermore, Giles et al (1987) reported on an increased risk for relapse in those dep,'essed patients who displayed a short REM latency both in the acute and in the relam~d ~tate. Even if the findings of a "depression-like" EEG sleep in rer~i~sion may indicate a
From the Max Planck Institute of Psychiatry, Clinical Institute, Department of Psychiatry, Munich, Germany. Address reprint requests to Dr. W. Schreiber, Max Planck Institute of Psychiatry, Department of Psychiatry, Kraepelinstrasse 10, W-8000 Munich 40, Germany. Received August 8, 1991; revised February 18, 1992. @ 1992 Society of Biological Psychiatry
0006-3223/92/$05.00
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"trait"-vulnerability for an affective disorder (Cartwright 1983), a critical point, however, cannot be ruled out by these studies: the persisting polysomnographic alterations can represent neurobiological abnormalities that have been acquired during previous episodes and have therefore to be considered as "biological scars" (Holsboer 1989). One strategy to circumvent this uncertainty is to investigate the polysomnograms of healthy first-degree relatives of patients with an affective disorder. Up to now, investigations along this line have been rather scanty and most of the existing studies are limited by the fact that relatives with and without a personal history of a psychiatric disorder were intermingled (Giles et al 1988, 1991). In fact, there is only one study focusing on EEG-sleep in first-degree relatives with and without a personal history of depression (Giles et al 1989). Both samples, however, comprised only those subjects in whom a reduced REM latency had been previously observed. Therefore, it is hardly surprising that virtually no differences in EEG-sleep could be observed between these two groups. We have taken up and extended this approach by examining subjects who have no current and no lifetime diagnosis of a psychiatric disorder but whe due to their family history--are at high risk for developing one. In these high-risk probands we have assessed a variety of psychometric, neuroendocrine, and polysomnographic parameters, all known to be usually altered in depression, and first results have already been reported (Krieg et al 1990). The all-night EEG sleep in these high-risk probands tended to be shallower than that of the controls (i.e., decreased sleep efficiency index, more frequent nocturnal awakenings, and less slow-wave sleep). No differences, however, could be confirmed regarding various REM sleep parameters. We attributed this lack of REM sleep alterations to the relatively young age of our high-risk subjects as there is converging evidence that young depressives can hardly be distinguished from 'other psychiatric patients or normal controls by means of their REM latency or amount of REM sleep (cf. Appelboom-Fondu et al 1988; Kupfer et al 1989; Lauer et al 1990, 1991; Goetz et al 1991). A different situation emerges when a dynamic challenge test, such as the cholinergic REM sleep induction test (RIT), is applied. The RIT has been proven to consistently differentiate between depressed patients and healthy volunteers by inducing the onset of REM sleep significantly faster in depressed patients (cf. Sitaram et al 1984; Berger et al 1985, 1989; Gillin et al 1991). Moreover, the effects of the RIT on REM sleep, that is, on REM latency, have been demonstrated to be identical in young and elderly depressed patients, indicating that the REM sleep triggering mechanisms in young depressives are already disturbedmbut on a subthreshold level not yet affecting baseline EEG sleep (Lauer et ai 1987, 1990). In the present study we explored whether a similar subthreshold disturbance of REM sleep triggering mechanisms can be demonstrated in our high-risk probands by means of the cholinergic REM sleep induction test.
Methods
Subjects Our selection p~cedure for the "high-risk probands" has been previously described in full detail (Krieg et al 1990); thus, only a short description is presented here: The high-risk pmband is a first-degree relative of an inpatient ("index patient") with the DSM-III-R diagnosis of an affective disorder, that is, a major depression, a manic episode, or a bipolar disorder (APA i98~; verified by the Structured Clinical Interview for DSM-III-R; SCID; German version: Wittchen et a11990); all patients with the diagnosis
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81
Table 1. Distribution o f D S M - I I I - R Diagnoses in the Families Identified to be at H i g h Risk for Psychiatric Disorders
Index patients (n = 15) First-degree relatives (n = 15)
Major depression
Manic episode
Bipolar disorder
Schizophrenic disorder
n = 10
n = 1
n = 4
none
n = 12
none
n = 1
n = 2
of a dysthymia or a depressive disorder not otherwise specified (NOS) were excluded from the study. The index patient has to have at least one further first-degree relative with the diagnosis of an affective disorder, a schizophrenic or schizoaffective disorder or an anxiety disorder (verified by the SCID) in order to ensure the a,,mpling of families highly loaded with psychiatric d~sorders. It has to be guaranteed that the high-risk proband is not suffering from either a current or lifetime DSM-III-R diagnosis of a psychiatric disorder (including dysthymia or depress~;on NOS; verified by the SCID). The cholinergic REM induction test (RIT) was performed with 1.5 mg RS 86 in 21 high-risk probands (HRP; 9 women, 12 men) from 15 different families; 10 families provided 1 HRP, 4 families 2 HRP, and 1 family 3 HRP. The distribution of DSM-IIIR diagnoses in these families is presented in Table 1. Seventeen healthy volunteers (from 17 different families) served as control subjects (CP; 9 women, 8 men). They were carefully screened to exclude any personal (using the SCID) or family (semistructured interview) history of psychiatric disorders. In case of doubt, the respective relatives of the CP were contacted personally to reconfirm the complete absence of psychiatric disorders in their families. All pm~icipants under investigation had been free of any prescription or nonprescription drug (including salicylates or antihistamines) for over 3 months. On the 2 days preceding the EEG sleep registration, no intake of caffeine (apart from a cup of coffee in the morning) or alcohol was allowed. The absence of insomnia, sleep apnea, or periodic leg movements was confirmed by clinical exploration and by the visual inspection of the polysomnograms of the placebo night. In case of doubt, exclusion from the study was fixed in the protocol. During the 2 weeks preceding the polysomnographic examination, both the HRP and the CP were instructed to go to bed between 10:30 PM and 11:30 PM in order to habituate to the "lights off" time as prescribed in the study protocol. They also had to fill in a sleep log during this time span. The tolerated latitude in deviation from the requested "lights off" time was about 30 min and controlled by the sleep log and a personal interview. Prior to the onset of the investigation, an extensive physical examination including electrocardiogram (EKCJ), blood analysis, and urinary drug monitoring was carried out. The study protocol was accepted by an ethics committee and written informed consent was obtained from all participants. All subjects under investigation were paid for their participation.
REM Sleep Induction Test (RIT) For the RIT, the spiropiperidyl derivate RS 86 was used, which is a direct, orally acting muscarinic agonist with a plasma half-life of 6-8 hr (P Bevan, unpublished data, 1981; Spiegel 1984; Palacios et al 1986). If any, only minor side effects have been reported
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after the intake of 1.5 mg RS 86 (Krieg et al 1987)--the dosage chosen for this investigation. After 1 night of habituation to the experimental setting, placebo or 1.5 mg RS 86, respectively were administered at 10:00 PM of nights 2 and 3. All subjects were blinded to the placebo-drag regimen. In the majority of the participants (76% of the high-risk probands and 65% of the control subjects) a placebo-RS 86 order was applied. Although Berger et al (1989) demonstrated the absence of both "time-serial" effects (placebo-RS 86 regimen) and "carry-over" effects (RS 86-placebo regimen) in a recent study applying the identical design, we chose an RS 86-placebo regimen in a subgroup of our participants in order to control for such possible order effects. Sleep was recorded from "lights off" (11:00 PM) until "lights on" (7:00 AM) using standard procedures: electroencephalogram (EEG; C3-A2, C4-Am), horizontal electrooculogram (EOG), and submental electromyogram. Records were visually scored according to standard criteria (Rechtschaffen and Kales 1968). In addition to the EEG sleep parameters usually determined (for definitions see Lauer et ai 1991), the following variables were calculated for the first and the second sleep cycle: the relative amount of time awake and of slow-wave sleep per nonREM period, the duration of the nonREM period, and REM period, respectively, and the length of the sleep cycle. All calculations were performed with a computerized program (Pollmiicher and Lauer 1992). Statistical analysis was carried out by a repeated measures m~zltivariate analysis of variance (MANOVA) with group (HRP versus CP) as between-subjects factor and trial (placebo versus RS 86) as within-subjects factor. In case of significant main effects for group or for trial, univariate F-tests were used in order to identify those EEG-sleep variables, which contribute to the overall group or trial differences. After determining such variables, their subeffects on group differences within each trial or on trial differences within each group were analyzed over parameter estimates for contrasts using the Student's t-test for independent or related samples, respectively. Due to multiple ,.~omparisons, the level of significance, which initially was set at 5%, was adjusted (Bonferroni procedure) in order to control for Type I enor.
Results Age-distribution and gender-distribution were similar between the HRP and the CP [age: T(I) - 0.37; gender: X2(I) - 0.08l. Application of the repeated measures multivariate analysis of variance resulted in significant main group- and trial-effects, but no significant intera,:~ion effects were observed [Wiiks multivariate tests of significance; effect of group: approximately F(I 8,27) = 2.28, p < 0.05; effect of trial: approximately F(18,27) - 2.66, p < 0.05l. Group means and SD of the EEG sleep variables considered in the analysis are summarized in Table 2 for both the placebo and the RS 86 night. Table 3 gives the results of the univariate F-tests within MANOVA; significant variable effects on the group or on the trial differences are indicated by an asterix (*). The significant main group effect was due to the amount of REM sleep, which was increased in the HRP [pooled over trials mean -+ SD: 22.6 ± 3.0 (~ g~'Tj versus 19.3 _.+ 4.0 (% SPT)] and to the REM density index of the second REM period, which was decreased in the HRP (pooled over taials mean _+ SD: 1.65 _~ 0.60 versus 2.16 +_ 0.92). The following variables contribute J to the significant main trial effect: the slow-wave
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Table 2. Effects of 1.5 mg RS 86 on EEG Sleep Vmiables in 21 High-Risk Probands and in 17 Control Probands High-risk probands EEG sleep parameters Sleep period time (min) Sleep efficiency index (%) Sleep onset latency (min) Slow-wave sleep latency (min) Number of awakenings Intermittent time awake (min) REM latency (lights off) (min) REM latency (sleep onse0 (min) Slow-wave sleep (% SFr) REM sleep (% SPT) Ist Sleep cycle REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density 2nd Sleep cycle NonREM period duration (min) REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density
Placebo night
RS 86 night
436.1 88.3 31.3 17.2 13.6 24.8 113.9 82.6 12.6 20.8
± ± ± ± _ ± ± ± ± ±
39.9 10.6 38.8 7.9 6.9 19.6 64.3 37.9 6.6 4.2
440.3 90.2 21.9 28.8 13.2 15.2 78.8 57.0 9.6 24.5
± ± ± ± ± ± ± ± ±
16.9 3.9 11.6 28.9 6.3 10.3 29.6 30.2 7.0 4.7
18.2 6.4 32.5 1.6
± ± ±
12.7 10.7 19.7 1.1
21.1 3.7 24.6 1.5
± ± ± ±
17.0 5.6 22.3 I.I
83.3 25.5 5.7 24.5 1.7
± ± ± ± ±
19.9 15.2 9.2 18.1 0.8
70.6 20.0 4.0 20.8 1.6
± ± ± ± ±
11.2 10.5 5.0 19.7 0.7
Control probands Sleep period time (min) Sleep efficiency index (%) Sleep onset latency (min) Slow-wave sleep latency (min) Number of awakenings Intermittent time awake (min) REM latency (lights off) (min) REM latency (sleep onset) (min) Slow-wave sleep (% SPT) REM sleep (% sp'r) i st Sleep cycle REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP~ REM density 2nd Sleep cycle NonREM period duration (min) REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density
430.7 88.5 25.3 19.3 I1.1 25.0 107.5 82.2 11.6 18.2
± ± ± ± ± ± ± ± --.
20.3 7.6 15.3 11.6 6.8 26.5 36.4 30.9 6.9 4.5
425.2 87.6 22.9 40.9 !i.2 25.5 93.2 70.2 9.1 20.5
± ± ± ± ± ± ± ± ± ±
28.3 6.9 10.7 44.6 9.0 22.1 38.6 35.0 5.7 5.5
16.4 2.6 33.7 !.7
± ± ± ±
12.1 4.6 22.6 0.6
17.7 9.6 21.9 !.4
± ± ± ±
12.0 15.8 24.2 1.0
84.3 25.3 5.0 17.1 2.2
± ± ±
23.1 14.3 7.9 16.0 I.I
73.4 17.9 4.5 21.7 2.1
--± ± ±
16.7 10.2 6.8 17.5 0.9
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W. Schreiber et al
Table 3. Results of the MANOVA Univariate F-tests in MANOVA Group
Trial
EEG sleep parameters
F(36,1)
Sleep period time (min) Sleep efficiency inde,~.(%) Sleep onset latency (rain) Slow-wave sleep latency (min) Number of awakenings Intermittent time awake (min) REM latency (lights off) (min) REM latency (sleep onset) (min) Slow-wave sleep (% SPT) REM sleep (% SPT) 1st Sleep cycle REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density 2nd Sleep cycle NonREM period duration (min) REM period duration (min) Time awake (% nonREMP) Slow-wave sleep (% nonREMP) REM density
1.7,, 0.96 0.19 1.06 !.33 1.22 0. I I 0.43 0.05 8.43
9.02 14.06 6.79 8.23
0.57 0.17 0.02
0.52 !.10 5.36
0.00
0.50
0.28 0.19 0,00 0.30
6.66 4.02 0.57 0.11
4,35
p
F(36,1) 0.03 0.37 1.45
9.64 0.01 1.03
*
!.26
*Indicates the variablesthat contribute significantlyto main group or trial effects.
sleep latency, which increased remarkably in the RS 86 night (pooled over groups mean ± SD: 18.2 ± 7.0 versus 34.85 ± 26.5); the slow-wave sleep (SWS) during the first nonREM period as well as during the total night, the relative amounts of which decreased after the administration of 1.5 mg RS 86 [pooled over groups mean + SD: 12.1 +_ 4.7 versus 9.35 ± 4.5 (% 1st nonREMP); 33.1 ± 14.9 versus 23.2 _ 16.4 (% SPT)]; the REM latency measurements (either from "lights off" or from "sleep onset"), which were shortened in the RS 86 night [pooled over groups mean ~: SD: 110.7 ± 24.4 min versus 86.0 _ 24.32 min ("lights off'); 82.4 ± 24.4 min versus 63.6 ± 23.1 min ("sleep onset")], and the amount of REM sleep, which was increased in the RS 86 night (pooled over groups mean _+ SD: 19.5 _ 3.0 % SP'I" versus 22.5 _ 3.6 % SPT). Furthermore, the duration of the second nonREM period was shortened in the drug night (pooled over groups mean ± SD: 83.8 _+ 15.24 min versus 72.0 ± 10.0 min). There was no influence of RS 86 on sleep continuity indices or on REM density measurements. The subeffects for the EEG sleep variables, which contrib~ted significantly to the group and trial differences are summarized in Table 4. During the placebo night, neither REM sleep nor REM density differed significantly between the two groups. During the RS 86 night, the HRP showed a significantly increased amount of REM sleep and their REM density index of the second REM period was decreased compared to the CP.
BIOL PSYCHIATRY 1992;32:79-90
REM Induction in High-Risk Probands
85
Table 4. Subeffects of the Variables Contributing Significantly to Main Group or Trial Effects Placebo night (HRP vs CP) Slow-wave sleep latency REM latency (lights off) REM latency (sleep onset) Slow-wave sleep REM sleep I st Sleep cycle Slow-wave sleep 2nd Sleep cycle NonREM period duration REM density
NS
NS
RS 86 night (HRP vs CP)
HRP (placebo vs RS 86 night)
CP (placebo vs RS 86 night)
*
NS • • • •
* NS NS NS NS
NS
*
NS
*
*
*Indicates significant differences; NS, not significant.
Comparing the placebo and the RS 86 night within the HRP and the CP separately, it was found that the CP showed a two-fold lengthening of the SWS latency and a decrease of the amount of SWS during the first nonR~M period. In the HRP, neither of these two EEG sleep parameters was significant!y affected by RS 86. Regarding REM latency, a significant shortening was observed in the HRP, but not in the CP (Figure 1). In more detail: whereas during the placebo night none of the subjects under investigation displayed a sleep onset REM period (SOREMP; REM latency < 25 rain), after the challenge with RS 86 this was the case in 3 (14%) HRP but in none of the CP. These differing frequencies of SOREMPs approximated the level of significance (X2[1] = 2.64, p < 0.10). The amount of REM sleep was significantly increased in the HRP, but not altered in the CP. Regarding the effects of RS 86 on the second sleep cycle, a significant shortening of the second nonREM period (= latency of the second REM period) was found in the HRP but not in the CP. Finally, since some subjects did not receive a placebo-RS 86 regimen but the inverse one, the EEG sleep parameters of the placebo night 2 (HRP: n = 16; CP: n = 11) and of the placebo night 3 (HRP: n = 5; CP: n = 6) were compared within the HRP and the CP, respectively. In agreement with the findings of Berger et al (1989), no differences were obtained. The same held true for the within-group comparisons of RS 86 night 3 and the RS 86 night 2. Discussion
The present study is the first to investigate the effects of a cholinomimetic on the EEG sleep pattern in a pure sample consisting of probands who as yet have not suffered from a psychiatric disorder, but who, due to their family history, run a high risk for developing onc.
Indeed, Sitaram et al (1987) investigated the effects of a cholinergic challenge on EEG sleep in subjects at high risk for psychiatric disorders. Using the arecoline-paradigm, the authors reported a more pronounced REM sleep-inducing effect in their high-risk probands than i~, 'heir control subjects. However, these observations are limited by the fact that higL-iisk probands with and without a personal history of a psychiatric disorder were
86
W. Schreiber et al
BIOL PSYCHIATRY 1992:32:79-90
rain
HRP
CP
p < o.ool
N.S.
q
160 -
P \
I I
\ 'e
140 -
\
\I \t,
120 -
/Y"~")~3
0,//i/`"
100
"o
8o
Figure !. Effect of RS 86 on REM Latency (Min from Sleep Onset) in 21 High-Risk Probands (HRP) and in 17 Control Subjects (CP).
60
40
20
PLACEBO
RS86
PLACEBO
RS86
intermingled, In contrast, our sample was restricted to only those probands who had not such a personal history but who are members of families that, in most cases, were highly loaded with affective disorders; this certainly provides a "pure" sample in this regard. Using this strategy, we tried to reduce the frequency of a false-positive identification of subjects at high risk (cL Krieg et al 1990). However, one has to keep in mind thatwlike in all other studies performed on high-risk probands--only a certain percentage of our HRP are genetically determined to be vulnerable for a psychiatric disorder. In a recent review of twin studies, McGuffin and Katz (1986) concluded that only about 20%-30% of healthy pedigrees of families highly loaded with psychiatric disorders are at "true" risk. Before discussing the results of the present study, one methodological aspect requires some comment: we are aware that our observations may be biased by the fact that in five of our families more than one high-risk proband was investigated. This cot~ld give rise to the critique that a possible genetically determined impact on the EEG sleep pattern could result in an overestimation or underestimation ef at least some of the effects observed in the present report. Up to now, there have only been a few studies dealing with the issue of genetic influences on EEG sleep (Webb and Campbell 1983, Hori 1986, Linkowski et al 1989, 1991). Taken together, a moderate concordance only among identical twins concerning REM sleep--the major focus of this studymhas to be assumed. This concordance, however, was found to be absent when looking at fraternal twins, whose genetic loa0 corresponds to the one of our HRP.
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During the placebo nighL no major difference between HRP and CP became evident. This finding is not consistent with our earlier report, in which the EEG sleep of the HRP was, in general, characterized by a decreased sleep quality (Krieg et al 1990). However, the subjects of the present study sample are not identical to those reported on earlier. Therefore, differing rates of subjects at "true" risk for psychiatric disorders may account for these inconsistencies. In this respect, one also has to consider how prominent a "premorbid marker" must be to be biostatistically confirmed in a group in which only 20%-30% of the subjects investigated are at "true" risk (Krieg et al 1990). The effects of 1.5 mg RS 86 on the EEG sleep pattern indicate rather different, preferential target sites of the cholinergic action on sleep regulating mechanisms in the HRP and in the CP: In the HRP the mean latencies of both the first and the second REM period were distinctly shorter in the drug night than in the placebo night. This finding is consistent with the above-mentionod report of Sitaram et al (1987). Furthermore, whereas none of our HRP had a spontaneous sleep onset REM period (SOREMP) in the placebo night, three of them (all were members of different families) displayed such a rapid onset of REM sleep after the application of RS 86. After a cholinergic challenge, such SOREMPs are reported to occur frequently in patients with a major depression but seem to be nearly completely absent in healthy subjects and in patients with other psychiatric disorders (i.e., anxiety disinters and eating disorde.rs; Berger et al 1985, 1989; Lauer et al 1988, 1990; Riemann et al 1990). Therefore, based on the observations of both an advanced onset of REM sleep and the increased occunence of SOREMPs, a subthreshold disturbance of the REM sleep-regulating systems, which appears to be comparable to that reported in young depressives (Lauer et al 1987, 1990), can be assumed in the HRP. On the other hand, signs of an increased arousal and/or an impaired slow-wave sleep were not present during the first nonREM period in the HRP. These findings suggest that REM sleeppromoting systems are the preferential target of RS 86 action in the HRP. Unfortunately, an estimation as to what extent a similar preferential target of cholinergic action, that is, of RS 86, is present in patients with a major depression cannot be made, since none of the respective studies has focused in detail on the EEG sleep parameters of the first nonREM period. In contrast, in the control subjects RS 86 caused a minor shortening of the first REM latency and induced effects that were mainly directed on the composition of the first nonREM period. These effects can best be characterized as a flattening of the quality of sleep (e.g., an increase of wake time, a two-fold prolongation of slow-wave sleep l~tency, and a one-third reduction of slow-wave sleep during this nonREM period). Thus, the administration of RS 86 resulted in an increased arousal paralleled by an impairment of slow-wave sleep. These findings are in line with studies performed in animals (rats and rabbits, respectively) and in humans (P Bevan, unpublished data, 1981; Spiegel 1984; Berkowitz et al 1990). Therefore, we assume that in our CP the preferential target of action of RS 86 is the weakening of the inhibitory function of nonREM sleep in both the arousal system and the REM sleep-promoting system, which, in part, was hypothesized by Kupfer et al (1984) and by Feinberg et al (1988). With regard to the mechanism of the RIT, Gillin et al (1979) proposed a direct action of cholinomimetics on muscarinic receptors of sleep-regulating neurons with the consequence of an earlier onset of REM sleep after a cholinergic challenge. In depression, these authors assumed an up-regulation of these muscarinic receptors to be responsible for the rapid onset of REM sleep (Gillin et al 1979). Therefore, a similar "depressionlike" up-regulation of muscarinic receptors might be postulated for (some of) our HRP
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but not for our CP. However, the hypothesis of an up-regulation of muscarinic receptors has been questioned by recent studies. Gillin et al (1991) failed to induce a shortening of REM latency when administering oxtremorine, a potent muscarinic agonist, to a strain of rats with an increased muscarinic receptor density in the brain. In addition, Riemann et al (1991) were not able to induce the depression-like early onset of REM sleep by a cholinergic challenge in healthy subjects who were pretreated with scopolamine in order to achieve muscari_nic receptor supersensitivity. Therefore, the induction of REM sleep may rather be related to an impaired REM-suppressive monoaminergic influence (Gillin et al 1982; Riemann et al 1991). Finally, reducing sleep regulation to a mere central cholinergic/aminergic interaction would neglect the involvement of other neurotransmitters and neuropeptides. For example, although the hermones of the iimbic-hypothalamicpituitary-adrenocortical (LHPA) axis do not appear to be directly involved in the regulation of REM sleep, they seem to act on nonREM sleep regulation (cf Holsboer et al 1988; Born et al 1989). In addition, the stimulatory effect of central cholinergic pathways on the LHPA system is well documented (e.g., Steiner and Grahame-Smith 1980). A pm,sible involvement of the LHPA axis in sleep regulatory processes is also of spe~:ial interest to us, because we could demonstrate that in a certain percentage of our HRP the feedback mechanisms of the LPHA axis regulating the secretory activity of its hormones are impaired in a similar manner as in depressed patients (Krieg et al 1991). To summarize our observations, by performing the REM sleep-induction test with 1.5 mg of the cholinergic agonist RS 86 in subjects at high risk for psychiatric disorders and in healthy volunteers not at risk, we found good evidence for (a) preferential targets of cholinergic action differing between subjects at high risk and control subjects and (b) a subthreshold disturbance of REM sleep-promoting systems in our high-risk probands. We are very grateful to A. Yassouridis, PhD, for his expert statistical assistance.
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