Circadian rhythm disturbances in depression

Susceptible period of socio-emotional development affected by constant exposure to daylight

As a diurnal experimental primate, the common marmoset (Callithrix jacchus) has recently contributed to numerous kinds of studies of neurobiological psychiatry as an essential pre-clinical model. The marmoset matures sexually within one or two years after birth. Thus, we can observe how the primate learns and develops psycho-cognitive functions through experiences in experimental environment for a much shorter period compared to that of humans. Longer daylight exposure may affect psychological development of children. In our research, we focus on raising marmosets under constant daylight from birth until various ages. In order to quantitatively evaluate the development of higher-ordered psychological functions, we designed a system of socio-behavioral tests and multivariate correlation analysis methods based on principal component analysis. With reference to the call and typical body movement expressed during a particular social context, we statistically inferred the emotional features of the subjects. In the current literature, we review our published results showing increased alert behaviors by constant light, and then, attempted to extend our additional analysis to seek age-dependent susceptibility to constant light. We then present the neurobiological mechanisms with reference to previous research reports. The current review suggests possible existence of a susceptible period earlier than three to five month-old in the environment-induced developmental disorder model, supposedly like attention deficit hyperactive disorders (ADHD) or oppositional defiant disorder (ODD).

Calculating the Social Rhythm Metric (SRM) and Examining Its Use in Interpersonal Social Rhythm Therapy (IPSRT) in a Healthy Population Study

In psychiatry, the social zeitgeber theory argues that social life provides important social cues that entrain circadian rhythms. Disturbance of these social cues might lead do dis-entrainment of circadian rhythms and evoke somatic symptoms that increase the risk of mood disorders. In preventing and treating patients with bipolar disorders, the Interpersonal and Social Rhythm Therapy (IPSRT) relies on the Social Rhythm Metric (SRM) to (re)establish patients' social cues and an re-entrain circadian rhythms. Since the SRM quantifies social rhythms that are derived from a patient's interaction with a social environment, this contribution (a) calculates the SRM of the social environment of a representative healthy population study (n = 1249), (b) evaluates the robustness of the SRM as a quantifier of social rhythms by matching the scores of the pilot study, revealing the near absence of variance across population characteristics and investigation months-circadian rhythms need to be entrained for every month and for everyone-and (c) examines its use in IPSRT by relating high SRM-scores to lower psychological distress (p = 0.004) and low SRM-scores to higher social and emotional dysfunction (p = 0.018).

Agomelatine: mechanism of action and pharmacological profile in relation to antidepressant properties

Agomelatine behaves both as a potent agonist at melatonin MT1 and MT2 receptors and as a neutral antagonist at 5-HT2C receptors. Accumulating evidence in a broad range of experimental procedures supports the notion that the psychotropic effects of agomelatine are due to the synergy between its melatonergic and 5-hydroxytryptaminergic effects. The recent demonstration of the existence of heteromeric complexes of MT1 and MT2 with 5-HT2C receptors at the cellular level may explain how these two properties of agomelatine translate into a synergistic action that, for example, leads to increases in hippocampal proliferation, maturation and survival through modulation of multiple cellular pathways (increase in trophic factors, synaptic remodelling, glutamate signalling) and key targets (early genes, kinases). The present review focuses on the pharmacological properties of this novel antidepressant. Its mechanism of action, strikingly different from that of conventional classes of antidepressants, opens perspectives towards a better understanding of the physiopathological bases underlying depression.

Local daily temperatures, thermal seasons, and suicide rates in Finland from 1974 to 2010

OBJECTIVES

Suicide peaks in late spring and October are still seen in Finland among many countries. Weather factors have been suggested as explanations for these peaks, although with inconsistent results. Since the exact timing of these peaks varies each year, the length of daylight and changes in it seem inadequate as an explanation. We hypothesized that ambient temperature and the timing of thermal seasons might associate with suicide rate.

METHODS

Suicide rates from three areas across Finland (N = 10,802) were analyzed with Poisson regression in six different models against variables calculated from the local ambient daily temperature, diurnal temperature range, and the duration from the onset of thermal seasons. Separate models for men and women were constructed.

RESULTS

The temperature change over 5 days associated with the suicide rate of men in Helsinki region, or in other words, the lower the suicide rate was, the higher the temperature decrease had been. For women, the results were more inconsistent.

CONCLUSIONS

Our study is in line with some earlier studies which imply that impairment of thermoregulation might exist among suicide victims.

Interpersonal and social rhythm group therapy for patients with bipolar disorder

This article describes Interpersonal and Social Rhythm Therapy (IPSRT) adapted for use in a group setting for patients with bipolar disorder. In a preliminary efficacy study, we studied the pre-post group treatment effect on affective symptoms. One-year pre-post findings in the IPSRT group indicated that this modality was effective in reducing depressive symptoms and might reduce the number of hospital admissions. Also, group IPSRT increased stability of the social rhythm, which is thought to be important in reducing recurrence of manic and depressive episodes. These findings suggest that group IPSRT could be an additional treatment option for patients with bipolar disorder who continue to have mood episodes despite adequate pharmacotherapy and psychoeducation.

PNI Biomarkers and Health Outcomes in College Women

Sleep disturbance has been found to trigger a stress response with a subsequent activation of the psychoneuroimmunological (PNI) pathway associated with adverse health outcomes. This study aimed to assess the association among selected PNI biomarkers, sleep disturbances, and adverse health outcomes (depressive symptoms, physical symptoms). A stratified, quota sample (14 poor sleepers and 15 good sleepers) was drawn from a pool of healthy college women from a larger scale of study. The participants reported their sleep, stress, depressive, and physical symptoms. Wrist actigraphy was used to collect objective sleep data, and the Enzyme-Linked ImmunoSorbent Assay was used to assess PNI biomarkers. Poor sleep quality, higher stress perception, elevated serum serotonin, and lower serum interleukin-10 explained 75.3% of the variances for the depressive symptoms. Poor sleep quality along with delayed peak activity rhythms accounted 31.4% of the physical symptoms. High serotonin and tumor necrosis factor-α were the significant predictors for poor sleep efficiency, and serotonin was the single significant predictor for poor daytime functioning. Stress and sleep disturbances negatively impact the health of college women and should be as part of regular check-ups on campus. PNI effects on health outcomes should be further explored. Educational materials in the areas of sleep hygiene, health impacts from sleep disturbances, and strategies to maintain synchronized circadian rhythms should be mandatorily included in the college curriculum.

Circadian misalignment and health

Circadian rhythms are near 24-h patterns of physiology and behaviour that are present independent of external cues including hormones, body temperature, mood, and sleep propensity. The term 'circadian misalignment' describes a variety of circumstances, such as inappropriately timed sleep and wake, misalignment of sleep/wake with feeding rhythms, or misaligned central and peripheral rhythms. The predominance of early research focused on misalignment of sleep to the biological night. However, discovery of clock genes and the presence of peripheral circadian oscillators have expanded the definitions of misalignment. Experimental studies conducted in animal models and humans have provided evidence of potential mechanisms that link misalignment to negative outcomes. These include dysregulation of feeding behaviours, changes in appetite stimulating hormones, glucose metabolism and mood. This review has two foci: (1) to describe how circadian misalignment has been defined and evaluated in laboratory and field experiments, and (2) to describe evidence linking different types of circadian misalignment to increased risk for physical (cardiovascular disease, diabetes, obesity, cancer) and psychiatric (depression, bipolar, schizophrenia, attention deficit) disorders. This review will describe the role of circadian misalignment as a risk factor for disease in the general population and in clinical populations, including circadian rhythm sleep disorders and psychiatric disorders.

Depressive symptoms and circadian activity rhythm disturbances in community-dwelling older women

OBJECTIVES

Aging is associated with changes in circadian rhythms. Current evidence supports a role for circadian rhythms in the pathophysiology of depression. However, little is known about the relationship between depressive symptoms and circadian activity rhythms in older adults. We examined this association in community-dwelling older women.

METHODS

We performed a cross-sectional analysis of 3,020 women (mean age: 83.55 ± 3.79 years) enrolled in the Study of Osteoporotic Fractures. Depressive symptoms were assessed with the Geriatric Depression Scale categorizing participants as "normal" (0-2; referent group, N = 1,961), "some depressive symptoms" (3-5, N = 704), or "depressed" (≥6, N = 355). Circadian activity rhythm variables were measured using wrist actigraphy.

RESULTS

In age-adjusted and Study of Osteoporotic Fractures site-adjusted models, greater levels of depressive symptoms were associated with decreased amplitude (height; df = 3,014, t = -11.31, p for linear trend <0.001), pseudo F-statistic (robustness; df = 3,014, t = -8.07, p for linear trend <0.001), and mesor (mean modeled activity; df = 3014, t = -10.36, p for linear trend <0.001) of circadian activity rhythms. Greater levels of depressive symptoms were also associated with increased odds of being in the lowest quartile for amplitude (df = 1, χ(2) = 9240, p for linear trend <0.001), pseudo F-statistic (df = 1, χ(2) = 49.73, p for linear trend <0.001), and mesor (df = 1, χ(2) = 81.12, p for linear trend <0.001). These associations remained significant in multivariate models. Post-hoc analyses comparing mean amplitude, mesor, and pseudo F-statistic values pair-wise between depression-level groups revealed significant differences between women with "some depressive symptoms" and the "normal" group.

CONCLUSION

These data suggest a graded association between greater levels of depressive symptoms and more desynchronization of circadian activity rhythms in community-dwelling older women. This association was observed even for women endorsing subthreshold levels of depressive symptoms.

Sleep-wake cycle in young and older persons with a lifetime history of mood disorders

Considering the marked changes in sleep and circadian rhythms across the lifespan, age may contribute to the heterogeneity in sleep-wake profiles linked to mood disorders. This study aimed to investigate the contributions of age and depression severity to sleep-wake disturbances. The Hamilton Depression Rating Scale (HDRS) was administered to assess current symptoms severity in 238 persons with a history of a mood disorder between 12 and 90 years of age (y.o.). Actigraphy was recorded over five to 22 days. Regression analyses and analyses of variance [age (12–19 y.o., 20–39 y.o., 40–59 y.o., and ≥60 y.o.) by depression severity (HDRS< and ≥8)] were conducted. The 12–19 y.o. and 20–39 y.o. groups had a delayed sleep schedule and acrophase compared to all other groups. The ≥60 y.o. group had a lower rhythmicity and amplitude (p≤.006) than the 12–19 y.o. group (p≤.046). Participants with a HDRS≥8 spent longer time in bed, had later sleep offset times and had lower circadian rhythmicity than those with a HDRS<8 (p≤.036). Younger age and higher HDRS score correlated with later sleep onset and offset times, longer time in bed, higher WASO, lower sleep efficiency and later acrophase (p≤.023). Age was a significant predictor of delayed sleep and activity schedules (p≤.001). The profile of sleep-wake cycle disturbances associated with mood disorders changes with age, with prominent sleep phase delay during youth and reduced circadian strength in older persons. Conversely, disruptions in sleep consolidation seem more stable across age.

Bright light therapy for depression: a review of its effects on chronobiology and the autonomic nervous system

Bright light therapy (BLT) is considered among the first-line treatments for seasonal affective disorder (SAD), yet a growing body of literature supports its use in other neuropsychiatric conditions including non-seasonal depression. Despite evidence of its antidepressant efficacy, clinical use of BLT remains highly variable internationally. In this article, we explore the autonomic effects of BLT and suggest that such effects may play a role in its antidepressant and chronotherapeutic properties. After providing a brief introduction on the clinical application of BLT, we review the chronobiological effects of BLT on depression and on the autonomic nervous system in depressed and non-depressed individuals with an emphasis on non-seasonal depression. Such a theory of autonomic modulation via BLT could serve to integrate aspects of recent work centered on alleviating allostatic load, the polyvagal theory, the neurovisceral integration model and emerging evidence on the roles of glutamate and gamma-hydroxybutyric acid (GABA).

Soluble amyloid-β levels and late-life depression

Late-Life Major Depression (LLMD) is a complex heterogeneous disorder that has multiple pathophysiological mechanisms such as medical comorbidity, vascular-related factors and Alzheimer's disease (AD). There is an association between LLMD and AD, with LLMD possibly being a risk factor for, or early symptom of AD and vascular dementia. Whether depression is an etiologic risk factor for dementia, or part of the dementia prodrome remains controversial. AD has a long prodromal period with the neuropathologic features of the disease preceding the onset of clinical symptoms by as much as 15-20 years. Clinicopathological studies have provided robust support for the importance of Aβ42 in the pathogenesis of AD, but several other risk factors have also been identified. Given the relationship between Aβ42 and AD, a potential relationship between Aβ42 and LLMD would improve the understanding of the association between LLMD and AD. We reviewed 15 studies that analyzed the relationship between soluble Aβ42 and LLMD. For studies looking at plasma and/or cerebrospinal fluid (CSF) levels of Aβ42, the relationship between LLMD and soluble Aβ42 was equivocal, with some studies finding elevated Aβ42 levels associated with LLMD and others finding the opposite, decreased levels of Aβ42 associated with LLMD. It may be that there is poor reliability in the diagnosis of depression in late life, or variability in the criteria and the scales used, or subtypes of depression in late life such as early vs. late onset depression, vascular-related depression, and preclinical/comorbid depression in AD. The different correlations associated with each of these factors would be causing the inconsistent results for soluble Aβ42 levels in LLMD, but it is also possible that these patterns derive from disease stage-dependent differences in the trajectory of CSF Aβ42 during older age, or changes in neuronal activity or the sleep/wake cycle produced by LLMD that influence Aβ42 dynamics.

Aging, circadian rhythms and depressive disorders: a review

INTRODUCTION

Aging is typically associated with impairing behavioral patterns that are frequently and inappropriately seen as normal. Circadian rhythm changes and depressive disorders have been increasingly proposed as the two main overlapping and interpenetrating changes that take place in older age. This study aims to review the state of the art on the subject concerning epidemiology, pathophysiological mechanism, clinical findings and relevance, as well as available treatment options.

MATERIALS AND METHODS

A nonsystematic review of all English language PubMed articles published between 1995 and December 2012 using the terms "circadian rhythms", "mood disorders", "depression", "age", "aging", "elderly" and "sleep".

DISCUSSION AND CONCLUSION

Sleep disorders, mainly insomnia, and depression have been demonstrated to be highly co-prevalent and mutually precipitating conditions in the elderly population. There is extensive research on the pathophysiological mechanisms through which age conditions circadian disruption, being the disruption of the Melatonin system one of the main changes. However, research linking clearly and unequivocally circadian disruption and mood disorders is still lacking. Nonetheless, there are consistently described molecular changes on shared genes and also several proposed pathophysiological models linking depression and sleep disruption, with clinical studies also suggesting a bi-directional relationship between these pathologies. In spite of this suggested relation, clinical evaluation of these conditions in elderly patients consistently reveals itself rather complicated due to the frequently co-existing co-morbidities, some of them having been demonstrated to alter sleep and mood patters. This is the case of strokes, forms of dementia such as Alzheimer and Parkinson, several neurodegenerative disorders, among others. Although there are to the present no specific treatment guidelines, available treatment options generally base themselves on the premise that depression and sleep disturbances share a bidirectional relationship and so, the adoption of measures that address specifically one of the conditions will reciprocally benefit the other. Treatment options range from Cognitive Behavioral Therapy, Chronotherapy, and Light therapy, to drugs such as Melatonin/Melatonin agonists, antidepressants and sedatives.

Diurnal alterations in circadian genes and peptides in major depressive disorder before and after escitalopram treatment

BACKGROUND

Strong links exist between circadian disturbances and some of the most characteristic symptoms of clinical major depressive disorder (MDD). However, changes in the expression of clock genes or neuropeptides related to the regulation of circadian rhythm that may influence the susceptibility to recurrence after antidepressant treatment in MDD have not been investigated.

METHODS

Blood samples were collected at 4h intervals for 24h from 12 male healthy controls and 12 male MDD patients before and after treatment with escitalopram for 8 weeks. The outcome measures included the relative expression of clock gene mRNA (PERIOD1, PERIOD2, PERIOD3, CRY1, BMAL1, NPAS2, and GSK-3β), and the levels of serum melatonin, vasoactive intestinal polypeptide (VIP), cortisol, adrenocorticotropic hormone (ACTH), insulin-like growth factor-1 (IGF-1), and growth hormone (GH).

RESULTS

Compared with healthy controls, MDD patients showed disruptions in the diurnal rhythms of the expression of PERIOD1, PERIOD2, CRY1, BMAL1, NPAS2, and GSK-3β and disruptions in the diurnal rhythms of the release of melatonin, VIP, cortisol, ACTH, IGF-1, and GH. Several of these disruptions (i.e., PER1, CRY1, melatonin, VIP, cortisol, ACTH, and IGF-1) persisted 8 weeks after escitalopram treatment, similar to the increase in the 24h levels of VIP and decreases in the 24h levels of cortisol and ACTH.

CONCLUSION

These persistent neurobiological changes may play a role in MDD symptoms that are thought to contribute to the vulnerability to recurrence and long-term maintenance therapy.

Psychosocial correlates of sleep quality and architecture in women with metastatic breast cancer

BACKGROUND

Sleep disturbance is prevalent among women with metastatic breast cancer (MBC). Our study examined the relationship of depression and marital status to sleep assessed over three nights of polysomnography (PSG).

METHODS

Women with MBC (N=103) were recruited; they were predominately white (88.2%) and 57.8±7.7 years of age. Linear regression analyses assessed relationships among depression, marital status, and sleep parameters.

RESULTS

Women with MBC who reported more depressive symptoms had lighter sleep (e.g., stage 1 sleep; P<.05), less slow-wave sleep (SWS) (P<.05), and less rapid eye movement (REM) sleep (P<.05). Single women had less total sleep time (TST) (P<.01), more wake after sleep onset (WASO) (P<.05), worse sleep efficiency (SE) (P<.05), lighter sleep (e.g., stage 1; P<.05), and less REM sleep (P<.05) than married women. Significant interactions indicated that depressed and single women had worse sleep quality than partnered women or those who were not depressed.

CONCLUSION

Women with MBC and greater symptoms of depression had increased light sleep and reduced SWS and REM sleep, and single women had worse sleep quality and greater light sleep than married counterparts. Marriage was related to improved sleep for women with more depressive 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.

Altered overnight modulation of spontaneous waking EEG reflects altered sleep homeostasis in major depressive disorder: a high-density EEG investigation

BACKGROUND

Prior investigations have suggested sleep homeostasis is altered in major depressive disorder (MDD). Low frequency activity (LFA) in the electroencephalogram during waking has been correlated with sleep slow wave activity (SWA), suggesting that waking LFA reflects sleep homeostasis in healthy individuals. This study investigated whether the overnight change in waking LFA and its relationship with sleep SWA are altered in MDD.

METHODS

256-channel high-density electroencephalography (hdEEG) recordings during waking (pre- and post-sleep) and during sleep were collected in 14 unmedicated, unipolar MDD subjects (9 women) and age- and sex-matched healthy controls (HC).

RESULTS

Waking LFA (3.25-6.25 Hz) declined significantly overnight in the HC group, but not in the group of MDD subjects. Overnight decline of waking LFA correlated with sleep SWA in frontal brain regions in HC, but a comparable relationship was not found in MDD.

LIMITATIONS

This study is not able to definitely segregate overnight changes in the waking EEG that may occur due to homeostatic and/or circadian factors.

CONCLUSIONS

MDD involves altered overnight modulation of waking low frequency EEG activity that may reflect altered sleep homeostasis in the disorder. Future research is required to determine the functional significance and clinical implications of these findings.

Major depressive disorder: a loss of circadian synchrony?

Circadian rhythms in the sleep/wake cycle, along with a range of physiological measures, are severely disrupted in individuals with major depressive disorder (MDD). Moreover, several central circadian genes have been implicated as potential genetic factors underlying the illness through candidate gene studies and some genome wide association studies. However, investigations into the molecular underpinnings of circadian disturbances in the human brain have been quite challenging. In their recent publication, Li and colleagues have used a novel approach to determine the rhythmic patterns of circadian gene expression in several regions of the human brain, and how these patterns are disrupted in MDD. Their findings demonstrate that in healthy subjects, several brain regions outside the suprachiasmatic nucleus (the master clock) exhibit diurnal gene expression patterns that are disrupted in the brains of MDD subjects. These findings will provide the foundation for future studies of gene-specific drug targets, and biomarkers for the disease.

Potency of melatonin in living beings

Living beings are surrounded by various changes exhibiting periodical rhythms in environment. The environmental changes are imprinted in organisms in various pattern. The phenomena are believed to match the external signal with organisms in order to increase their survival rate. The signals are categorized into circadian, seasonal, and annual cycles. Among the cycles, the circadian rhythm is regarded as the most important factor because its periodicity is in harmony with the levels of melatonin secreted from pineal gland. Melatonin is produced by the absence of light and its presence displays darkness. Melatonin plays various roles in creatures. Therefore, this review is to introduce the diverse potential ability of melatonin in manifold aspects in living organism.

Stability and fragmentation of the activity rhythm across the sleep-wake cycle: the importance of age, lifestyle, and mental health

The rhythms of activity across the 24-h sleep-wake cycle, determined in part by the circadian clock, change with aging. Few large-scale studies measured the activity rhythm objectively in the general population. The present population-based study in middle-aged and elderly persons evaluated how activity rhythms change with age, and additionally investigated sociodemographics, mental health, lifestyle, and sleep characteristics as determinants of rhythms of activity. Activity rhythms were measured objectively with actigraphy. Recordings of at least 96 h (138 ± 14 h, mean ± SD) were collected from 1734 people (age: 62 ± 9.4 yrs) participating in the Rotterdam Study. Activity rhythms were quantified by calculating interdaily stability, i.e., the stability of the rhythm over days, and intradaily variability, i.e., the fragmentation of the rhythm relative to its 24-h amplitude. We assessed age, gender, presence of a partner, employment, cognitive functioning, depressive symptoms, body mass index (BMI), coffee use, alcohol use, and smoking as determinants. The results indicate that older age is associated with a more stable 24-h activity profile (β = 0.07, p = 0.02), but also with a more fragmented distribution of periods of activity and inactivity (β = 0.20, p < 0.001). Having more depressive symptoms was related to less stable (β = -0.07, p = 0.005) and more fragmented (β = 0.10, p < 0.001) rhythms. A high BMI and smoking were also associated with less stable rhythms (BMI: β = -0.11, p < 0.001; smoking: β = -0.11, p < 0.001) and more fragmented rhythms (BMI: β = 0.09, p < 0.001; smoking: β = 0.11, p < 0.001). We conclude that with older age the 24-h activity rhythm becomes more rigid, whereas the ability to maintain either an active or inactive state for a longer period of time is compromised. Both characteristics appear to be important for major health issues in old age.

Manipulating melatonin in managing mood

OBJECTIVE

Disturbances in circadian rhythms have been associated with major depression and may be an underlying mechanism for the disorder. Resynchronisation of circadian rhythms may provide a new approach to treatment, especially by manipulating melatonin secretion. Melatonin is secreted at night and is a stable marker of circadian rhythms. The timing of its secretion can be changed by exogenous melatonin, agonism of specific melatonin receptors in the suprachiasmatic nucleus, its suppression by light and by sleep deprivation.

METHOD

As part of a series of papers ['Chronobiology of mood disorders' Malhi & Kuiper. Acta Psychiatr Scand 2013;128 (Suppl. 444): 2-15; and 'Getting depression clinical practice guidelines right: time for change?' Kuiper et al. Acta Psychiatr Scand 2013;128 (Suppl. 444): 24-30.] addressing chronobiology, in this article, we conducted a selective review of studies that have examined the antidepressant effects of exogenous melatonin, light therapy, sleep deprivation and melatonin receptor agonists.

RESULTS

Antidepressant effects were identified for bright light therapy, especially for seasonal affective disorder; sleep deprivation, although its antidepressant effect is time limited; and for the novel antidepressant agomelatine with agonistic properties for the MT1 and MT2 receptors and antagonism of 5HT2c receptor. The role of melatonin as an antidepressant has yet to be demonstrated.

CONCLUSION

Shifting the circadian secretion of melatonin using the strategies reviewed offers a new approach to treating depression.

The efficacy of agomelatine in previously-treated depressed patients

OBJECTIVE

Post-hoc analysis of two randomized controlled trials with agomelatine was undertaken to compare data on pretreated versus untreated patients with major depressive disorder.

METHOD

Selected trials were Olié and Kasper (2007), a placebo-controlled trial, and Kasper et al. (2010), a randomized, double-blind comparison with sertraline.

RESULTS

A total of 40% and 57.7% of patients had been pretreated with antidepressants in the placebo-controlled trial and sertraline-controlled trial, respectively. In the previously-treated patients in the placebo-controlled study, the mean decrease in the total score on the HAM-D₁₇ over 6 weeks was significantly greater with agomelatine than placebo (delta=4.43, P=0.005) and 67.5% of patients were responders. In the previously-treated patients of the sertraline-controlled study, the improvement on the HAM-D₁₇ total score remained numerically higher with agomelatine (delta=1.63, P=0.124), with 55.2% responders. In both studies, agomelatine was well tolerated.

CONCLUSION

Data from the subset of previously treated depressed patients, who can be considered more difficult to treat, indicate that agomelatine, due to its different mode of action, demonstrated antidepressant efficacy, and favorable side effect profile-with proven benefits in first-line treatment-is also an effective candidate for patients with major depressive disorder previously treated with other antidepressants.

Relationships among circadian typology, psychological symptoms, and sensation seeking

Recently, attention has been focused on the relationship among circadian typology, psychiatric symptoms, and personality traits. This study analyzes the influence of circadian typology on psychological distress, and the sensation-seeking personality trait. Five hundred seventeen college students (173 males), aged 17 to 30, answered the Composite Scale of Morningness (CSM), the General Health Questionnaire 28-item version (GHQ-28), and the Sensation Seeking Scale-V (SSS-V). The evening-type subjects in our sample scored higher than the neither- and morning- type in the GHQ-28 total score, as well as in the four subscales that composed it (Psychosomatic Symptoms, Anxiety and Insomnia, Social Dysfunction, and Severe Depression) (p<0.02 in all cases). The evening-type subjects also had a larger proportion of psychiatric cases than the other two circadian typologies (p<0.0001 in all cases). Moreover, the evening-type subjects obtained higher scores in the SSS-V total score and in the subscales of Disinhibition and Boredom Susceptibility (p<0.001 in all cases). A positive correlation was observed between the GHQ-28 and the SSS-V total scores in the total sample, but only for the evening-type group (r=0.217; p<0.027). In the evening group, several relations were also found between the subscales of the GHQ-28 and the subscales of the SSS-V (r>0.206; p<0.036). All these data point to a relationship between evening-type subjects and the level of psychological distress and the sensation-seeking personality trait. They also suggest that eveningness could be related to developing psychological distress and personality traits that could, in turn, be related to developing other problems, such as drug consumption.

Circadian sleep-wake rhythm of older adults with intellectual disabilities

The circadian sleep-wake rhythm changes with aging, resulting in a more fragmented sleep-wake pattern. In individuals with intellectual disabilities (ID), brain structures regulating the sleep-wake rhythm might be affected. The aims of this study were to compare the sleep-wake rhythm of older adults with ID to that of older adults in the general population, and to investigate which factors are associated with the sleep-wake rhythm in older adults with ID. This study is part of the 'Healthy Aging and Intellectual Disabilities' study (HA-ID). We applied actigraphy in 551 persons with ID and 58 persons in the general population, aged 50 years and over. Outcome measures were stability (interdaily stability), fragmentation (intradaily variability) and amplitude (relative amplitude) of the sleep-wake rhythm. Compared to older adults in the general population, the sleep-wake rhythm of older adults with ID was significantly less stable (p=0.03), more fragmented (p<0.001) and had a lower relative amplitude (p<0.001). Multivariate regression analysis revealed that higher age, dementia, depression, visual impairment, severe hearing impairment, epilepsy and spasticity are independently associated with a more disturbed sleep-wake rhythm in this group. The sleep-wake rhythm is more stable in females and those living at a setting for more intensive care. Higher physical activity levels are strongly associated with both a less fragmented (p<0.001) and a more stable (p<0.001) sleep-wake rhythm. Higher age, dementia and depression are also associated with the sleep-wake rhythm in the general population. Neurological and sensory impairments that were associated with the sleep-wake rhythm in older adults with ID, are frequent known conditions in the ID population. Further research should focus on which factors specifically influence the sleep-wake rhythm in older adults with ID, and on the effects of more physical daytime activity on the sleep-wake rhythm in this population.

Manipulating the sleep-wake cycle and circadian rhythms to improve clinical management of major depression

BACKGROUND

Clinical psychiatry has always been limited by the lack of objective tests to substantiate diagnoses and a lack of specific treatments that target underlying pathophysiology. One area in which these twin failures has been most frustrating is major depression. Due to very considerable progress in the basic and clinical neurosciences of sleep-wake cycles and underlying circadian systems this situation is now rapidly changing.

DISCUSSION

The development of specific behavioral or pharmacological strategies that target these basic regulatory systems is driving renewed clinical interest. Here, we explore the extent to which objective tests of sleep-wake cycles and circadian function - namely, those that measure timing or synchrony of circadian-dependent physiology as well as daytime activity and nighttime sleep patterns - can be used to identify a sub-class of patients with major depression who have disturbed circadian profiles.

SUMMARY

Once this unique pathophysiology is characterized, a highly personalized treatment plan can be proposed and monitored. New treatments will now be designed and old treatments re-evaluated on the basis of their effects on objective measures of sleep-wake cycles, circadian rhythms and related metabolic systems.

Delayed sleep phase in young people with unipolar or bipolar affective disorders

BACKGROUND

Circadian disturbances may play a key role in the pathogenesis of some forms of mood disorders. Despite marked changes in circadian rhythms during the normal course of adolescence and young adulthood, less is known about changes in the 24-h sleep-wake cycle in young persons with mood disorders.

METHODS

Seventy-five young participants with mood disorders (unipolar: n=46, 20.1 ± 4.7 years old; bipolar I or II: n=29, 23.2 ± 4.3) and 20 healthy participants (24.8 ± 2.5 years old) underwent actigraphy monitoring during a depressive phase over seven consecutive days and nights. Sleep phase delay was defined as mean sleep onset ≥ 1:30 am and/or sleep offset ≥ 1 0:00 am.

RESULTS

A delayed sleep phase was found in 62% of participants with bipolar disorders when depressed, compared with 30% of those with unipolar depression (χ(2)=6.0, p=0.014) and 10% of control participants (χ(2)=11.2, p<0.001). Sleep offset times were significantly later in subjects with mood disorders compared to the control group, and later in those with bipolar as compared with unipolar disorders (all p ≤ 0.043).

LIMITATIONS

This study was cross-sectional and the depressed groups were somewhat younger compared to the healthy controls. Longitudinal studies are required to determine the predictive significance of these findings.

CONCLUSIONS

Young patients with mood disorders, especially those with bipolar disorders, are particularly likely to have a delayed sleep phase. Therapies focused on advancing sleep phase may be of specific benefit to these young persons.

Comparison of five actigraphy scoring methods with bipolar disorder

The goal of this study was to compare 5 actigraphy scoring methods in a sample of 18 remitted patients with bipolar disorder. Actigraphy records were processed using five different scoring methods relying on the sleep diary; the event-marker; the software-provided automatic algorithm; the automatic algorithm supplemented by the event-marker; visual inspection (VI) only. The algorithm and the VI methods differed from the other methods for many actigraphy parameters of interest. Particularly, the algorithm method yielded longer sleep duration, and the VI method yielded shorter sleep latency compared to the other methods. The present findings provide guidance for the selection of signal processing method based on sleep parameters of interest, time-cue sources and availability, and related scoring time costs for the study.

Pilot investigation of the circadian plasma melatonin rhythm across the menstrual cycle in a small group of women with premenstrual dysphoric disorder

Women with premenstrual dysphoric disorder (PMDD) experience mood deterioration and altered circadian rhythms during the luteal phase (LP) of their menstrual cycles. Disturbed circadian rhythms may be involved in the development of clinical mood states, though this relationship is not fully characterized in PMDD. We therefore conducted an extensive chronobiological characterization of the melatonin rhythm in a small group of PMDD women and female controls. In this pilot study, participants included five women with PMDD and five age-matched controls with no evidence of menstrual-related mood disorders. Participants underwent two 24-hour laboratory visits, during the follicular phase (FP) and LP of the menstrual cycle, consisting of intensive physiological monitoring under “unmasked”, time-isolation conditions. Measures included visual analogue scale for mood, ovarian hormones, and 24-hour plasma melatonin. Mood significantly (P≤.03) worsened during LP in PMDD compared to FP and controls. Progesterone was significantly (P = .025) increased during LP compared to FP, with no between-group differences. Compared to controls, PMDD women had significantly (P<.05) decreased melatonin at circadian phases spanning the biological night during both menstrual phases and reduced amplitude of its circadian rhythm during LP. PMDD women also had reduced area under the curve of melatonin during LP compared to FP. PMDD women showed affected circadian melatonin rhythms, with reduced nocturnal secretion and amplitude during the symptomatic phase compared to controls. Despite our small sample size, these pilot findings support a role for disturbed circadian rhythms in affective disorders. Possible associations with disrupted serotonergic transmission are proposed.

Bright light therapy protects women from circadian rhythm desynchronization during chemotherapy for breast cancer

Circadian rhythms (CRs) are commonly disrupted in women undergoing chemotherapy for breast cancer (BC). Bright light improves and strengthens CRs in other populations. This randomized controlled study examined the effect of morning administration of bright light therapy on CRs in women undergoing chemotherapy for BC. It was hypothesized that women receiving bright light therapy would exhibit more robust rhythms than women exposed to dim light. Thirty-nine women newly diagnosed with BC and scheduled for chemotherapy were randomized into 2 groups: bright white light (BWL) or dim red light (DRL). Women were instructed to use the light box every morning for 30 min during their first 4 cycles of chemotherapy. Wrist actigraphy was recorded at 5 time points: prior to chemotherapy (baseline), Cycle-1 treatment week (C1TW), Cycle-1 recovery week (C1RW), Cycle-4 treatment week (C4TW), and Cycle-4 recovery week (C4RW). There was a Group × Time interaction at C4TW compared to baseline such that the DRL group showed significant deterioration in the mean of the activity rhythm (mesor) and amplitude, whereas the BWL group exhibited a significant increase in both mesor and amplitude. The DRL group also exhibited significant deterioration in overall rhythm robustness at C1TW, C4TW, and C4RW. Women in the BWL group also showed significant decreases in overall rhythm robustness at C1TW and C4TW, but returned to baseline levels at both recovery weeks. The results suggest that morning administration of bright light may protect women from experiencing CR deterioration during chemotherapy.

LY2033298, a positive allosteric modulator at muscarinic M₄ receptors, enhances inhibition by oxotremorine of light-induced phase shifts in hamster circadian activity rhythms

RATIONALE

Entrainment of circadian rhythms to the light-dark cycle is essential for restorative sleep, and abnormal sleep timing is implicated in central nervous system (CNS) disorders like depression, schizophrenia, and Alzheimer's disease. Many transmitters, including acetylcholine, that exerts its actions via muscarinic receptors modulate the suprachiasmatic nucleus, the master pacemaker.

OBJECTIVES

Since positive allosteric modulators of muscarinic M(4) receptors are candidates for treatment of mood and cognitive deficits of CNS disorders, it is important to evaluate their circadian actions.

MATERIALS AND METHODS

The effects of intraperitoneally applied muscarinic agents on circadian wheel-running rhythms were measured employing hamsters, a model organism for studying activity rhythms.

RESULTS

Systemic administration of the muscarinic receptor agonist oxotremorine (0.01-0.04 mg/kg) inhibited light-induced phase delays and advances of hamster circadian wheel-running rhythms. The M₄ positive allosteric modulator, LY2033298 (10-40 mg/kg), had no effect on light-induced phase shifts when administered alone, yet significantly enhanced (at 20 mg/kg) the inhibitory influence of oxotremorine on light-induced phase delays. In addition, the muscarinic receptor antagonist, scopolamine, which was without effect on light-induced phase shifts when administered alone (0.001-0.1 mg/kg), antagonized (at 0.1 mg/kg) the inhibitory effect of oxotremorine and LY2033298 on light-induced phase delays.

CONCLUSIONS

These results are the first to demonstrate that systemically applied muscarinic receptor agonists modulate circadian activity rhythms, and they also reveal a specific role for M₄ receptors. It will be of importance to evaluate circadian actions of psychotropic drugs acting via M₄ receptors, since they may display beneficial properties under pathological conditions.

Atmospheric pressure and suicide attempts in Helsinki, Finland

The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods (P < 0.001), and may explain the clustering of suicide attempts. Men seem to be more vulnerable to attempt suicide under low atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

Does activity matter: an exploratory study among mothers with preterm infants?

The purpose of this study was to describe the daytime activity levels and their association with sleep, fatigue, depressive symptoms, and quality of life. Wrist actigraphy and questionnaires were used to examine 51 mothers with a preterm infant during their second week postpartum. Circadian activity rhythms (CAR) were less synchronized in these mothers; they experienced sleep disturbances, fatigue, depressive symptoms, and poor health-related quality of life (H-QOL). Compared to high-activity mothers, mothers with low activity levels slept less during nighttime but napped more during daytime, and reported more postpartum depressive symptoms. Further research is needed to examine the effect of low activity level and sleep loss on postpartum depression, and to develop interventions for improving rest/activity patterns for new mothers.

Bright Light Therapy to Promote Sleep in Mothers of Low-Birth-Weight Infants

Having a low-birth-weight (LBW) infant in a neonatal intensive care unit (NICU) can intensify a mother’s sleep disturbances due to both stress and the dim lighting in the ICU setting, which desynchronizes circadian rhythms. The purpose of this pilot study was to examine the effectiveness of a 3-week bright light therapy intervention on sleep and health outcomes of mothers with LBW infants in the NICU. Controlled stratified randomization was used to assign 30 mothers to a treatment or control group. Data were collected at pretreatment (second week postpartum) and after the 3-week intervention. Sleep data were assessed by wrist actigraph (total sleep time [TST], circadian activity rhythms [CARs]) and the General Sleep Disturbance scale. Other outcome variables were measured by the Lee’s Fatigue scale, Edinburgh Postpartum Depression scale, and the Medical Outcomes Short Form 36, version 2. Mothers averaged 26.6 ( SD = 6.3) years of age, and the majority were Black (73%). The mean gestational age for the infants was 27.7 ( SD = 2.0) weeks. Small to large effect sizes were found when comparing the pre- to posttreatment differences between groups. Although none of the differences were statistically significant in this small sample, for mothers in the treatment group nocturnal TST ( d = .33), CAR ( d = 1.06), morning fatigue ( d = .22), depressive symptoms ( d = .40), physical health–related quality of life ( d = .33), and mental health–related quality of life ( d = .60) all improved compared to the control group. Bright light therapy is feasible for mothers with infants in an NICU. Clinically significant improvements have been evidenced; a larger-scale trial of effectiveness is needed.

Beneficial behavioural and neurogenic effects of agomelatine in a model of depression/anxiety

Agomelatine (S20098) is a novel antidepressant drug with melatonergic agonist and 5-HT2C receptor antagonist properties, displaying antidepressant/anxiolytic-like properties in animal models and in humans. In a depression/anxiety-like mouse model in which the response of the HPA axis is blunted, we investigated whether agomelatine could reverse behavioural deficits related to depression/anxiety compared to the classical selective serotonin reuptake inhibitor, fluoxetine. Adult mice were treated for 8 wk with either vehicle or corticosterone (35 μg/ml.d) via drinking water. During the final 4 wk, animals were treated with vehicle, agomelatine (10 or 40 mg/kg i.p.) or fluoxetine (18 mg/kg i.p.) and tested in several behavioural paradigms and also evaluated for home-cage activity. Our results showed that the depressive/anxiety-like phenotype induced by corticosterone treatment is reversed by either chronic agomelatine or fluoxetine treatment. Moreover, agomelatine increased the dark/light ratio of home-cage activity in vehicle-treated mice and reversed the alterations in this ratio induced by chronic corticosterone, suggesting a normalization of disturbed circadian rhythms. Finally, we investigated the effects of this new antidepressant on neurogenesis. Agomelatine reversed the decreased cell proliferation in the whole hippocampus in corticosterone-treated mice and increased maturation of newborn neurons in both vehicle- and corticosterone-treated mice. Overall, the present study suggests that agomelatine, with its distinct mechanism of action based on the synergy between the melatonergic agonist and 5-HT2C antagonist properties, provides a distinct antidepressant/anxiolytic spectrum including circadian rhythm normalization.

Little things on which happiness depends: microRNAs as novel therapeutic targets for the treatment of anxiety and depression

Anxiety and depression are devastating mental illnesses that are a significant public health concern. Selective serotonin-reuptake inhibitors are the first-line treatment strategy for these disorders, which despite being a significant advantage over older treatments, are hampered by a limited efficacy in a significant subset of patients, delayed onset of action and side effects that affect compliance. Thus, there is much impetus to develop novel therapeutic strategies. However, this goal can only be rationally realised with a better understanding of the molecular pathophysiology of these disorders. MicroRNAs (miRNAs) are a newly discovered class of gene-expression regulators that may represent a novel class of therapeutic targets to treat a variety of disorders including psychiatric diseases. miRNAs are heavily involved in regulating many physiological processes including those fundamental to the functioning of the central nervous system. Evidence collected to date has already demonstrated that miRNA-expression levels are altered in patients suffering from depression and anxiety and in pre-clinical models of psychological stress. Furthermore, increasing evidence suggests that psychoactive agents including antidepressants and mood stabilisers utilise miRNAs as downstream effectors. Altering miRNA levels has been shown to alter behaviour in a therapeutically desirable manner in pre-clinical models. This review aims to outline the evidence collected to date demonstrating miRNAs role in anxiety and depression, the potential advantages of targeting these small RNA molecules as well as some of the hurdles that will have to be overcome to fully exploit their therapeutic potential.

Stress and health-related well-being among mothers with a low birth weight infant: the role of sleep

This U.S.A.-based study examined the quantitative and qualitative characteristics of sleep, as well as the role of sleep, in the association of stress with depression, fatigue, and health-related quality of life (H-QOL) among mothers with a low-birth-weight, preterm infant in the neonatal intensive care unit at early postpartum. Fifty-five first-time mothers kept a sleep diary and filled out a battery of questionnaires. The wrist actigraphy method was also applied to collect information on maternal sleep. We tested a path model, with sleep disturbance and depression mediating the effect of stress on health-related well-being. Results showed that the majority of the study participants were stressed, depressed, fatigued, and at risk for poor physical and mental health. Poor sleep quality as perceived by mothers was significantly associated with their stress, fatigue, and poor mental and physical H-QOL. A cascading effect was found in the path model where maternal stress contributed to poor sleep quality and depression, which in turn contributed to poor mental H-QOL. In addition, poor sleep quality was associated with fatigue, which in turn contributed to poor physical and mental H-QOL. The underlying neurobiological mechanisms through which sleep affects the stress-health relation are discussed. The implications of sleep for intervention and prevention are also addressed.

Inborn differences in environmental reactivity predict divergent diurnal behavioral, endocrine, and gene expression rhythms

Circadian dysfunction has long been implicated in the etiology of mood disorders. The gene Clock and related molecules (e.g. Per1, Per2) represent key regulators of circadian rhythmicity, and their targeted disruption in mutant mice produces potentiated reward drive, novelty-seeking, impulsivity, disrupted sleep, reduced depression and anxiety - a behavioral profile highly reminiscent of our selectively bred high responder (bHR) rats compared to bred low responders (bLRs). The current study evaluated potential diurnal bHR-bLR differences in behavior, gene expression, and neuroendocrinology. Relative to bHRs, bLRs showed diminished homecage locomotion during the dark (but not light) phase and a delayed corticosterone peak. In situ hybridizations in hypothalamus, amygdala, and hippocampus at Zeitgeber Time (ZT)2 and ZT14 revealed distinct bHR-bLR day-night gene expression fluctuations. bHRs exhibited altered day-night patterns of corticotrophin releasing hormone (CRH) and arginine vasopression (AVP) mRNA in the hypothalamus, and perturbed hippocampal MR:GR ratios relative to bLR rats. bHR-bLR rats showed disparate day-night Clock expression in the suprachiasmatic nucleus, a master circadian oscillator, with bHRs showing higher levels at ZT14 versus ZT2 and bLRs showing the opposite pattern. Clock, Per1 and Per2 were assessed in the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) since disruption of these genes induces "bHR-like" behavior in mutant mice. Clock and Per1 did not differ between strains, but there were robust Per2 differences, with bHRs having reduced Per2 in VTA and SNc. These findings resonate with earlier work demonstrating that perturbation of Clock and related molecules contributes to disturbances of emotional and addictive behaviors.

Circadian disruption leads to loss of homeostasis and disease

The relevance of a synchronized temporal order for adaptation and homeostasis is discussed in this review. We present evidence suggesting that an altered temporal order between the biological clock and external temporal signals leads to disease. Evidence mainly based on a rodent model of “night work” using forced activity during the sleep phase suggests that altered activity and feeding schedules, out of phase from the light/dark cycle, may be the main cause for the loss of circadian synchrony and disease. It is proposed that by avoiding food intake during sleep hours the circadian misalignment and adverse consequences can be prevented. This review does not attempt to present a thorough revision of the literature, but instead it aims to highlight the association between circadian disruption and disease with special emphasis on the contribution of feeding schedules in circadian synchrony.