Minute-by-minute analysis of REM sleep timing in major depression

Effects of acute tryptophan depletion on raphé functional connectivity in depression

Depression remains a great societal burden and a major treatment challenge. Most antidepressant medications target serotonergic raphé nuclei. Acute tryptophan depletion (ATD) modulates serotonin function. To better understand the raphé's role in mood networks, we studied raphé functional connectivity in depression. Fifteen depressed patients were treated with sertraline for 12 weeks and scanned during ATD and sham conditions. Based on our previous findings in a separate cohort, resting state MRI functional connectivity between raphé and other depression-related regions (ROIs) was analyzed in narrow frequency bands. ATD decreased raphé functional connectivity with the bilateral thalamus within 0.025-0.05 Hz, and also decreased raphé functional connectivity with the right pregenual anterior cingulate cortex within 0.05-0.1 Hz. Using the control broadband filter 0.01-0.1 Hz, no significant differences in raphé-ROI functional connectivity were observed. Post-hoc analysis by remission status suggested increased raphé functional connectivity with left pregenual anterior cingulate cortex in remitters (n=10) and decreased raphé functional connectivity with left thalamus in non-remitters (n=5), both within 0.025-0.05 Hz. Reducing serotonin function appears to alter coordination of these mood-related networks in specific, low frequency ranges. For examination of effects of reduced serotonin function on mood-related networks, specific low frequency BOLD fMRI signals can identify regions implicated in neural circuitry and may enable clinically-relevant interpretation of functional connectivity measures. The biological significance of these low frequency signals detected in the raphé merits further study.

The effects of galantamine and buspirone on sleep structure: Implications for understanding sleep abnormalities in major depression

RATIONALE

The serotonergic and cholinergic systems are jointly involved in regulating sleep, but this balance is theorized to be disturbed in depressed individuals.

OBJECTIVE

The goal of this study was to use biological probes in healthy participants, to model the serotonergic/cholinergic imbalance of depression and its associated abnormalities in sleep structure.

METHODS

We tested 20 healthy female participants 18-30 years of age on four non-consecutive nights. Participants were given galantamine (a cholinergic agent), buspirone (a serotonergic agonist), both drugs together, or placebo before sleeping.

RESULTS

Buspirone suppressed tonic rapid eye movement (REM): There was a significant increase in REM latency (p < 0.001). Galantamine increased tonic REM sleep, leading to more time spent in REM (p < 0.001) and shorter REM latency (p < 0.01). Galantamine and buspirone given together were not significantly different from the placebo night by REM sleep measures, but disrupted sleep more than either drug alone.

CONCLUSIONS

These findings are partially consistent with the cholinergic literature about sleep in depression, notably short REM latency, higher percentage of total sleep time spent in REM and increased sleep fragmentation. The prolonged REM latency and reduced percentage of REM with buspirone resembled the effect of selective serotonin reuptake inhibitor antidepressants on REM sleep.

Oscillatory serotonin function in depression

Oscillations in brain activities with periods of minutes to hours may be critical for normal mood behaviors. Ultradian (faster than circadian) rhythms of mood behaviors and associated central nervous system activities are altered in depression. Recent data suggest that ultradian rhythms in serotonin (5HT) function also change in depression. In two separate studies, 5HT metabolites in cerebrospinal fluid (CSF) were measured every 10 min for 24 h before and after chronic antidepressant treatment. Antidepressant treatments were associated with enhanced ultradian amplitudes of CSF metabolite levels. Another study used resting-state functional magnetic resonance imaging (fMRI) to measure amplitudes of dorsal raphé activation cycles following sham or active dietary depletions of the 5HT precursor (tryptophan). During depletion, amplitudes of dorsal raphé activation cycles increased with rapid 6 s periods (about 0.18 Hz) while functional connectivity weakened between dorsal raphé and thalamus at slower periods of 20 s (0.05 Hz). A third approach studied MDMA (ecstasy, 3,4-methylenedioxy-N-methylamphetamine) users because of their chronically diminished 5HT function compared with non-MDMA polysubstance users (Karageorgiou et al., 2009). Compared with a non-MDMA using cohort, MDMA users showed diminished fMRI intra-regional coherence in motor regions along with altered functional connectivity, again suggesting effects of altered 5HT oscillatory function. These data support a hypothesis that qualities of ultradian oscillations in 5HT function may critically influence moods and behaviors. Dysfunctional 5HT rhythms in depression may be a common endpoint and biomarker for depression, linking dysfunction of slow brain network oscillators to 5HT mechanisms affected by commonly available treatments. 5HT oscillatory dysfunction may define illness subtypes and predict responses to serotonergic agents. Further studies of 5HT oscillations in depression are indicated.

Circadian rhythm disturbances in depression

OBJECTIVE

The aim of this article is to review progress in understanding the mechanisms that underlie circadian and sleep rhythms, and their role in the pathogenesis and treatment of depression.

METHODS

Literature was selected principally by Medline searches, and additional reports were identified based on ongoing research activities in the authors' laboratory.

RESULTS

Many physiological processes show circadian rhythms of activity. Sleep and waking are the most obvious circadian rhythms in mammals. There is considerable evidence that circadian and sleep disturbances are important in the pathophysiology of mood disorders. Depressed patients often show altered circadian rhythms, sleep disturbances, and diurnal mood variation. Chronotherapies, including bright light exposure, sleep deprivation, and social rhythm therapies, may be useful adjuncts in non-seasonal and seasonal depression. Antidepressant drugs have marked effects on circadian processes and sleep.

CONCLUSIONS

Recent progress in understanding chronobiological and sleep regulation mechanisms may provide novel insights and avenues into the development of new pharmacological and behavioral treatment strategies for mood disorders.

Is psychotherapy an effective treatment for melancholia and other severe depressive states?

The treatment of severe depression with psychotherapy, alone, is controversial. In this paper, we review the historical, conceptual, and empirical contexts of this controversy. In addition to work by others, we review recent work from our institute which has examined the psychobiological substrates of response to treatment in depressive subtypes. We examine the traditional categories that describe severe depressions. The features and psychobiological correlates of melancholia are discussed, as is the relationship between melancholia and aging. Research on treatment of melancholia and other severe depressive states with psychotherapies such as cognitive behavior therapy (CBT) and interpersonal psychotherapy (IPT) is reviewed in detail. We conclude that although some melancholic patients are responsive to IPT or CBT, there is not yet compelling evidence that melancholic patients respond to psychotherapy as well as they do to medications. The potentially mediating effects of hypercortisolism, alterations of sleep neurophysiology, and disturbances of information processing and regional cerebral metabolism represent fertile grounds for future investigation. We discuss the practical implications of the literature reviewed.

Critical analysis of the theories advanced to explain short REM sleep latencies and other sleep anomalies in several psychiatric conditions

One of the most consistent and most studied sleep modifications in several psychiatric conditions is the shortening of the rapid eye movement (REM) sleep latency. While its clinical usefulness is still to be proven and its meaning relatively obscure, the appearance of a short REM latency continues to be a daily fact in sleep laboratories. Many theories compete to explain what is observed, the most important being the circadian rhythm hypotheses, the homeostatic model and the reciprocal interaction model. These three are summarised and their pros and cons are exposed in a systematic manner. Points of conflict, possible convergences and limitations are discussed in the light of recent developments on the general theories of sleep regulation.

Identifying an abnormal electroencephalographic sleep profile to characterize major depressive disorder

There is little agreement as to the best definition of a categorically abnormal electroencephalographic (EEG) sleep profile to characterize major depressive disorder. Therefore, a series of classification, replication, and validation analyses were conducted to identify such a profile. The EEG sleep studies of healthy controls (n = 44), depressed inpatients (n = 44), and depressed outpatients (n = 181) were utilized, including subgroups of patients studied both before and after nonpharmacologic treatment with either cognitive behavior therapy (CBT) or interpersonal psychotherapy (IPT). A discriminant index score (based on reduced REM latency, increased REM density, and decreased sleep efficiency) was found to: 1) reliably discriminate between depressed inpatients, depressed outpatients, and controls; 2) show good test-retest reliability; and 3) identify a subset of depressed outpatients who were older, manifested a broader array of EEG sleep disturbances, and were less responsive to CBT or IPT. Posttreatment studies of patients indicated that normal sleep profiles were relatively stable, whereas abnormal profiles tended to normalize. These findings provide an empirically validated method that may improve the applicability, efficiency, and prognostic utility of EEG sleep studies of depressed patients.

Circadian rhythms and the pharmacology of affective illness

The chronic effects of antidepressant drugs (ADs) on circadian rhythms of behavior, physiology and endocrinology are reviewed. The timekeeping properties of several classes of ADs, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, serotonin agonists and antagonists, benzodiazepines, and melatonin are reviewed. Pharmacological effects on the circadian amplitude and phase, as well as effects on day-night measurements of motor activity, sleep-wake, body temperature (Tb), 3-methoxy-4-hydroxyphenylglycol, cortisol, thyroid hormone, prolactin, growth hormone and melatonin are examined. ADs often lower nocturnal Tb and affect the homeostatic regulation of sleep. ADs often advance the timing and decrease the amount of slow wave sleep, reduce rapid eye movement sleep and increase or decrease arousal. Together, AD effects on nocturnal Tb and sleep may be related to their therapeutic properties. ADs sometimes delay nocturnal cortisol timing and increase nocturnal melatonin, thyroid hormone and prolactin levels; these effects often vary with diagnosis, and clinical state. The effects of ADs on the coupling of the central circadian pacemaker to photic and nonphotic zeitgebers are discussed.

Electroencephalographic sleep profiles in single-episode and recurrent unipolar forms of major depression: I. Comparison during acute depressive states

The current study was conducted to examine if recurrent depression is associated with more severe disturbances of all-night EEG sleep profiles than single-episode depressions. Unmedicated sex- and age-matched groups of 22 single-episode (SE) and 44 recurrent unipolar (RU) outpatients with DSM-III-R/SADS/RDC major depression underwent 2 consecutive nights of EEG sleep recording. Multivariate analyses of covariance (MANCOVAs) and/or analyses of covariance (ANCOVAs) were performed on six sets of sleep measures. Recurrent unipolar depression was associated with significantly increased phasic REM sleep, as well as increased REM counts on the second night of study. Recurrent depression also was associated with significantly poorer sleep efficiency, although the groups did not show consistent differences in sleep architecture or slow-wave sleep. Our findings generally support the hypothesis that recurrent depression is associated with a more severe neurophysiologic substrate than phenotypically similar SE cases. Results are, for the most part, compatible with Post's (1992) model of illness progression, particularly with respect to greater disturbances of state-dependent sleep abnormalities in the RU cases. Longitudinal studies are needed to confirm the evolution of such changes prospectively.

Does the function of REM sleep concern non-REM sleep or waking?

We have hypothesized that REM sleep is functionally and homeostatically related to NREM sleep rather than to waking. In other words, REM sleep rather than to waking. In other words, REM sleep occurs in response to NREM-sleep expression and compensates for some process that takes place during NREM sleep. Under normal conditions, the need for REM sleep does not accrue during waking. The primary basis for this hypothesis is the fact that REM-sleep expression is a function of prior NREM-sleep expression. That is, REM sleep follows NREM sleep within sleep periods, REM-sleep episodes occur at intervals determined by the amount of NREM-sleep time elapsed, and total time spent in REM sleep is consistently about 1/4 of prior NREM-sleep time, regardless of how much time is spent in NREM sleep. Our experimental tests of the hypothesis support it. (1) REM-sleep propensity accumulates quite rapidly during a 2-hr interval spent predominantly in NREM sleep. (2) The timing of individual REM-sleep episodes is controlled homeostatically, by accumulation within NREM sleep of a propensity for REM sleep. The NREM sleep-related model of REM-sleep regulation (Fig. 1) explains a number of phenomena of REM-sleep expression, including the frequent and periodic occurrence of REM-sleep episodes throughout sleep periods, that have been accommodated by the waking-related model but are not functionally accounted for by it. In our opinion, the NREM sleep-related model of REM-sleep regulation recommends itself partly by its simplicity. According to the waking-related model, two independent and competing sleep propensities accumulate during waking and are discharged in two distinct sleep states that perform different waking-related recovery processes. One behaviour, sleep, is thought to perform two independent and competing functions that alternate at regular intervals. In the NREM sleep-related model of REM-sleep regulation, sleep debt simply reflects a need for NREM sleep. That is, the cerebrally less activated state of NREM sleep enables some form of restoration made necessary by the cerebrally activated state of waking. Periodic occurrence of REM-sleep episodes is explained without postulating an oscillatory mechanism to gate expression of NREM sleep versus REM sleep. In assessing the comparative merits of the waking-related and NREM sleep-related models of REM-sleep regulation, one should consider the influence of time-worn habits of thought.(ABSTRACT TRUNCATED AT 400 WORDS)

[Sleep and biological rhythms in depression. Changes caused by antidepressants]

Sleep in depression is characterized by an increase in the number and duration of awakenings, sleep instability, and SWS decrease. REM sleep occurs earlier. REMs density during the 1st REM period is higher than in normal controls matched in age. Accordingly, sleep in depression is similar to sleep in normal aging. Endogenous depression cannot be distinguished from other types of depression by means of polygraphic criteria. Sleep recordings at the beginning of tricyclic compound treatment could be predictive of clinical response to treatment. Sleep modifications induced by antidepressive drugs are reviewed. Sleep recordings enabled us to formulate several physiopathological hypotheses of depression mechanisms: cholinergic-aminergic hypothesis, phase advance, deficiency of process S. Other hypotheses are reviewed: flattening of a hypothetical circadian rhythm of arousal, depressogenic property of sleep in itself (or only of SWS) or timing delay for the start of sleep. A significant phase advance of biological rhythms (temperature, cortisol) is rarely found. A reduction in the amplitude of rhythms (temperature, TSH, melatonine) is more frequent.

Electroencephalographic sleep in clinically stable schizophrenic patients: two-weeks versus six-weeks neuroleptic-free

EEG sleep studies in schizophrenic patients are influenced by alterations in clinical state and medication status. The current study defines longitudinal alterations in electroencephalographic (EEG) sleep for 10 healthy men who were schizophrenic patients who remained relatively clinically stable during a double-blind neuroleptic withdrawal study. Clinical assessments and EEG sleep studies were performed at baseline on haloperidol, and then at 2-week and 6-week drug-free periods. Sleep continuity and rapid eye movement (REM) sleep measures declined not only between the haloperidol baseline and 2-week drug-free conditions, but continued to decline from 2-week to 6-weeks neuroleptic-free. Alterations in EEG sleep from the 2-week to 6-week haloperidol-free assessments did not correlate with changes in clinical symptoms suggesting effects related to drug-withdrawal or subclinical state changes. These results show that despite relative clinical stability over time, the EEG sleep of schizophrenic patients continues to change following withdrawal of a neuroleptic and is dependent on the duration of the drug-free interval.

Good sleep, bad sleep: a meta-analysis of polysomnographic measures in insomnia, depression, and narcolepsy

Primary insomnia, major depression, and narcolepsy are usually considered to be separate disorders, distinguished by different polysomnographic profiles. But do polysomnographic data provide adequate evidence to segregate the three disorders, or might they display fundamentally the same sleep disturbance, differing only in degree? To test the viability of these two alternate hypotheses, the authors performed a meta-analysis of controlled polysomnographic studies of these disorders. A summary measure of degree of sleep disturbance was constructed from five variables: wakefulness after sleep onset, percentage of stage 1 sleep, percentage of stage 3 + 4 sleep, rapid eye movement (REM) latency, and REM density. The results of available studies for each variable were combined using a weighted average of effect sizes. An overall "sleep disturbance index" was then calculated by combining the estimates for the five above listed variables. On both the individual measures and especially on the summary index, insomnia, depression, and narcolepsy were arrayed on a simple continuum of progressively more severe sleep disturbance--congruent with the clinical observation that these disorders display progressively more disturbed sleep. These findings suggest that sleep can be disturbed in only a limited number of ways: in evaluating sleep architecture, it may not be possible to elaborate much beyond a single axis of good-to-bad sleep. Thus, polysomnographic measures may not provide adequate evidence to classify insomnia, depression, and narcolepsy as separate entities.

Electroencephalographic sleep studies in depressed outpatients treated with interpersonal psychotherapy: I. Baseline studies in responders and nonresponders

Electroencephalographic (EEG) sleep measures have been examined as predictors of therapeutic response in patients with major depression. Although some studies have reported that EEG sleep measures are predictive of a favorable outcome with medications, two recent studies found no differences in the baseline sleep characteristics of responders and nonresponders to psychotherapy. To clarify this issue, we compared baseline EEG sleep in a group of patients with recurrent depression who responded to interpersonal psychotherapy (n = 19) and a comparable group who did not respond (n = 18). Baseline ratings of depression severity did not differ in the groups, but some differences in baseline sleep were noted. Psychotherapy nonresponders had longer sleep latencies, lower sleep efficiency, and increased automated measures of phasic rapid eye movement (REM) activity. In addition, the two groups had different EEG sleep adaptation patterns for REM latency and phasic REM density measures across the two study nights. These preliminary results suggest that baseline EEG sleep patterns, as well as the pattern of laboratory adaptation, may differ for depressed patients who respond to psychotherapy and those who do not.