Neuroendocrine and sleep variables in major depressed inpatients: role of severity

Atypical depression and non-atypical depression: Is HPA axis function a biomarker? A systematic review

BACKGROUND

The link between the abnormalities of the Hypothalamic-pituitary-adrenal (HPA) axis and depression has been one of the most consistently reported findings in psychiatry. At the same time, multiple studies have demonstrated a stronger association between the increased activation of HPA-axis and melancholic, or endogenous depression subtype. This association has not been confirmed for the atypical subtype, and some researchers have suggested that as an antinomic depressive subtype, it may be associated with the opposite type, i.e. hypo-function, of the HPA-axis, similarly to PTSD. The purpose of this systematic review is to summarise existing studies addressing the abnormalities of the HPA-axis in melancholic and/or atypical depression.

METHOD

We conducted a systematic review in the literature by searching MEDLINE, PsycINFO, OvidSP and Embase databases until June 2017. The following search items were used: "hypothalamic-pituitary-adrenal" OR "HPA" OR "cortisol" OR "corticotropin releasing hormone" OR "corticotropin releasing factor" OR "glucocorticoid*" OR "adrenocorticotropic hormone" OR "ACTH" AND "atypical depression" OR "non-atypical depression" OR "melancholic depression" OR "non-melancholic depression" OR "endogenous depression" OR "endogenomorphic depression" OR "non-endogenous depression". Search limits were set to include papers in English or German language published in peer-reviewed journals at any period. All studies were scrutinized to determine the main methodological characteristics, and particularly possible sources of bias influencing the results reported.

RESULTS

We selected 48 relevant studies. Detailed analysis of the methodologies used in the studies revealed significant variability especially regarding the samples' definition comparing the HPA axis activity of melancholic patients to atypical depression, including healthy controls. The results were subdivided into 4 sections: (1) 27 studies which compared melancholic OR endogenous depression vs. non-melancholic or non-endogenous depression or controls; (2) 9 studies which compared atypical depression or atypical traits vs. non-atypical depression or controls; (3) 7 studies which compared melancholic or endogenous and atypical depression subtypes and (4) 5 studies which used a longitudinal design, comparing the measures of HPA-axis across two or more time points. While the majority of studies did confirm the association between melancholic depression and increased post-challenge cortisol levels, the association with increases in basal cortisol and basal ACTH were less consistent. Some studies, particularly those focusing on reversed vegetative symptoms, demonstrated a decrease in the activity of the HPA axis in atypical depression compared to controls, but the majority did not distinguish it from healthy controls.

CONCLUSIONS

In conclusion, our findings indicate that there is a difference in the activity of the HPA-axis between melancholic and atypical depressive subtypes. However, these are more likely explained by hypercortisolism in melancholia; and most often normal than decreased function in atypical depression. Further research should seek to distinguish a particular subtype of depression linked to HPA-axis abnormalities, based on symptom profile, with a focus on vegetative symptoms, neuroendocrine probes, and the history of adverse childhood events. New insights into the dichotomy addressed in this review might be obtained from genetic and epigenetic studies of HPA-axis related genes in both subtypes, with an emphasis on the presence of vegetative symptoms.

Sleep as a biomarker for depression

Sleep is a complex biological process that involves cyclic changes of brain activity. The smooth transition between wakefulness and sleep and cyclic succession of sleep stages depend on the function of numerous neurotransmitters that reciprocally influence each other. For this reason sleep is a very sensitive biomarker of brain functioning. This article provides an overview of sleep changes in depression, mechanisms involved in sleep regulation and pathophysiology underlying depression, studies on sleep as a biomarker for depression, effects of antidepressants on sleep EEG, and studies in depression with the use of quantitative sleep EEG analysis. Research on sleep in depression has provided several valuable biomarkers that are related to increased risk for depression, show worsening during depressive episode, and are related to treatment outcome and relapse risk during remission phase. Among many sleep parameters, increased REM density and diminished delta sleep ratio deserve special interest. Sleep studies are also an important research tool for antidepressant drug development. However, due to sensitivity of sleep parameters to pharmacological interventions, the patients have to be investigated before the start of pharmacological treatment or after washout from the antidepressant drug, to obtain reliable data on disease-related biological processes from polysomnography.

Classification of depressive disorders in the DSM-V: proposal for a two-dimension system

The number of categories and specifiers for mood disorders has increased with each successive edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM). Many of these categories and specifiers can be viewed as an effort to map the various permutations of severity and chronicity that characterize the depressive disorders. However, this has resulted in a system that (a) is unnecessarily complex and unwieldy, (b) has created problems with artificial distinctions between categories and artifactual comorbidity, and (c) at the same time obscures what may be more fundamental distinctions. A potentially useful and more parsimonious approach to capturing much of the heterogeneity of depressive disorders is to classify the depressive disorders along 2 dimensions, 1 reflecting severity and the other, chronicity. Considerations in the development of these dimensions are discussed, and a set of examples is presented. Although further research and discussion are needed to determine the optimal form of these dimensions, the next edition of the DSM should consider replacing many of the existing categories and specifiers for depressive disorders with the simpler approach of classifying depressive disorders using the 2 dimensions of severity and chronicity.

Sleep onset REM periods in obsessive compulsive disorder

Sleep studies in patients with obsessive compulsive disorder (OCD) are sparse and results inconsistent. Moreover, in 3 out of 4 published studies up to 50% of patients suffered from secondary major depression. In this study, 10 inpatients with a DSM-IV diagnosis of OCD without comorbid major depression (Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score >15; Hamilton Depression Rating Scale (HAMD)-21 total score <17) and 10 healthy matched controls were included. Polysomnography of patients (7 males, 3 females, 34.5+/-12.7 years, Y-BOCS: 27.8+/-4.6, HAMD-21: 13.3+/-1.9) and controls (7 males, 3 females, 34.4+/-12.8 years) was recorded, following an adaptation night. Sleep variables did not significantly differ in both groups except that stage 4 sleep was reduced in patients. Three of the patients with OCD, however, exhibited sleep onset REM periods (SOREMPs), i.e. rapid-eye-movement (REM) latencies <10 min. Obsessive compulsive symptoms were significantly (P<0.05) more severe in these patients (Y-BOCS: 32+/-2.0) compared to those without SOREMPs (Y-BOCS 26+/-4.2). This is, to our knowledge, the first report of sleep onset REM periods in OCD.

Sleeping in? The impact of age and depressive sub-type on hypersomnia

BACKGROUND

While early morning wakening is held to be a classic feature of melancholia, we investigate the clinical observation that young patients with melancholia and bipolar depression tend to be more likely to report hypersomnia.

METHODS

We examine age-related rates of those two sleep disturbance patterns in a consecutive set of out-patients with differing depressive sub-types assessed over a 20-year period.

RESULTS

Hypersomnia was more likely to be reported than early morning wakening across all age bands by those with non-melancholic depression. Hypersomnia was also more likely than early morning wakening in younger patients with melancholia and bipolar disorder but, with age, early morning wakening became the dominant pattern.

LIMITATIONS

The study was retrospective, undertaken in a sample attending a tertiary referral unit and artefactual determinants of the associations were not pursued.

CONCLUSIONS

We speculate that hypersomnia may be a non-specific homeostatic coping response to stress and thus to the non-melancholic depressive disorders, but that this pattern is overruled by an early morning wakening pattern in the more biological depressive sub-types as the individual ages, perhaps reflecting a noradrenergic contribution.

Sleep microstructure around sleep onset differentiates major depressive insomnia from primary insomnia

In the present study we investigate whether alterations of sleep propensity or of wake propensity are implicated in sleep initiation disturbances encountered in major depressive insomnia and in primary insomnia. For this purpose, the time course of electroencephalogram (EEG) power density during the period preceding sleep onset and during the first non-rapid eye movement (REM) period was examined in three age and gender matched groups of 10 women and 11 men (healthy controls, primary insomniacs and depressive insomniacs). In contrast to healthy controls and depressive insomniacs, patients with primary insomnia did not experience a gradual decrease of their alpha and beta1 power during the sleep onset period and had a lower delta activity in the 5 min preceding sleep onset. Compared with the two other groups, depressive patients exhibit less dynamic changes in slow wave activity during the first non-REM period. The present results suggest that hyperarousal (high 'Process W') may mainly be implicated in the sleep initiation difficulties of primary insomniacs whereas the homeostatic sleep regulation process seems to be partially maintained. In our major depressed patients, the sleep initiation disturbances appeared to relate to a lower sleep pressure (low 'Process S') rather than to hyperarousal. This study supports the idea that different mechanisms are implicated in sleep disturbances experienced by primary insomniacs and major depressive insomniacs.

Sleep-wake mechanisms and drug discovery: sleep EEG as a tool for the development of CNS-acting drugs

Sleep laboratory investigations constitute a unique noninvasive tool to analyze brain functioning, Polysomnographic recordings, even in the very early phase of development in humans, are mandatory in a developmental plan of a new sleep-acting compound. Sleep is also an interesting tool for the development of other drugs acting on the central nervous system (CNS), Indeed, changes in sleep electroencephalographic (EEG) characteristics are a very sensitive indication of the objective central effects of psychoactive drugs, and these changes are specific to the way the drug acts on the brain neurotransmitter systems. Moreover, new compounds can be compared with reference drugs in terms of the sleep EEG profile they induce. For instance, cognitive enhancers involving cholinergic mechanism have been consistently demonstrated to increase rapid eye movement (REM) sleep pressure, and studying drug-induced slow wave sleep (SWS) alteration is a particularly useful tool for the development of CNS compounds acting at the 5-HT(2A/C) receptor, such as most atypical antipsychotics and some antidepressant drugs. The sleep EEG profile of antidepressants, and particularly their effects on REM sleep, are specific to their ability to enhance noradrenergic or serotonergic transmission, it is suggested that the effects of noradrenergic versus serotonergic reuptake inhibition could be disentangled using specific monoamine depletion tests and by studying drug effects on sleep microsiructure.

Disturbances in hypothalamo pituitary adrenal and thyroid axis identify different sleep EEG patterns in major depressed patients

This study was aimed at investigating the relationships between sleep EEG abnormalities and hypothalamo pituitary adrenal (HPA) and hypothalamo pituitary thyroid (HPT) disturbances in major depressive disorder. Post dexamethasone (DXM) cortisol levels and the dual TSH response to 08:00 h and 23:00 h TRH administration were determined after a 2 weeks wash-out period in a group of 113 DSM-IV major depressed patients (72 females aged 44.3+/-13.0 and 41 males aged 45.7+/-11) who were consecutively admitted to undergo sleep EEG recordings. Post-DXM cortisolemia, 08:00 and 23:00 post-TRH TSH values, time spent in rapid eye movement sleep (REMS), in slow wave sleep (SWS), and in stage 2 as well as time awake after sleep onset were introduced in a principal component (PC) analysis. The four 3 PC scores explaining up to 74% of the data set were further calculated for each patients and used in a cluster analysis. A three-cluster solution was retained. Controlling for the effects of age and gender, patients belonging to these three clusters could clearly be differentiated on the basis of their neuroendocrine responses and on their sleep EEG profiles. Compared to the two other clusters, cluster I (n=26) patients showed the most severe sleep continuity disturbances. Post-DXM cortisol escape and sleep architecture disturbances (consisting of a shortening of REMS latency and a decreased SWS) identified patients belonging to cluster II (n=39). Patients in cluster III (n=48) had the lowest TSH response to TRH and the less marked sleep EEG alteration. Clinical or demographic variables were unable to differentiate the three clusters. Our results suggest that different biological dysfunctions could each underlie particular neuroendocrine and sleep EEG disturbances in major depression.

Morning and evening TSH response to TRH and sleep EEG disturbances in major depressive disorder

1. The aim of this study was to investigate hypothalamo-pituitary-thyroid axis (HPTA) functioning and sleep EEG disturbances in major depressive disorder. 2. Thyroid function was evaluated by determination of TSH levels before and after 8 AM and 11 PM TRH administration on the same day in a sample of 113 consecutively-admitted DSM-IV major depressed inpatients (72 females aged 44.3 +/- 13.0 and 41 males aged 45.7 +/- 10.7) that underwent sleep EEG recordings. 3. A blunted TSH response occurred in 15.9% for 8 AM deltaTSH (maximum increment above baseline at the 8 AM TRH challenge), in 39.8% for 11 PM deltaTSH and in 77% for deltadeltaTSH (difference between 11 PM deltaTSH and 8 AM deltaTSH). A negative correlation between deltadeltaTSH and duration of awakenings after sleep onset, and a shorter sleep onset latency in patients with a blunted 11 PM deltaTSH were found, but these two significant relationships disappeared after controlling for the effects of gender and age. 4. The present findings do not support the hypothesis that, in major depression, HPTA dysfunctioning, as reflected in TSH response to TRH, may be related to sleep EEG disturbances.

Neuroendocrine and clinical characteristics of major depressed patients exhibiting sleep-onset REM

BACKGROUND

Previous reports suggest an association between sleep-onset REM (SOREM) and some clinical characteristics in depressive illness such as age, psychosis, and depression severity. The present study is aimed at further investigating clinical and neuroendocrine correlates of SOREM, controlling for the age-related variability in clinical data.

METHODS

Thyroid-stimulating hormone response to thyrotropin-releasing hormone, postdexamethasone cortisol levels, and clinical characteristics of 25 major depressive (MD) patients exhibiting SOREM in at least one of three consecutive recording nights were compared to those of 25 age- and sex-matched MD patients with three REM latencies above 50 min.

RESULTS

SOREM patients experienced more affective episodes leading to hospitalization and a shorter duration of current episode than patients with three REM latencies above 50 min. No association between psychosis and SOREM could be demonstrated, and hypothalamic-pituitary-adrenal or -thyroid axis disturbances were not more prevalent in SOREM patients.

CONCLUSIONS

Our results suggest that clinical history rather than cross-sectional clinical characteristics relates to the occurrence of SOREM in major depressed patients.