An overview of seasonal affective disorder and its treatment options

Circadian rhythms as modulators of brain health during development and throughout aging

The circadian clock plays a prominent role in neurons during development and throughout aging. This review covers topics pertinent to the role of 24-h rhythms in neuronal development and function, and their tendency to decline with aging. Pharmacological or behavioral modification that augment the function of our internal clock may be central to decline of cognitive disease and to future chronotherapy for aging-related diseases of the central nervous system.

Light as a modulator of emotion and cognition: Lessons learned from studying a diurnal rodent

Light profoundly affects the behavior and physiology of almost all animals, including humans. One such effect in humans is that the level of illumination during the day positively contributes to affective well-being and cognitive function. However, the neural mechanisms underlying the effects of daytime light intensity on affect and cognition are poorly understood. One barrier for progress in this area is that almost all laboratory animal models studied are nocturnal. There are substantial differences in how light affects nocturnal and diurnal species, e.g., light induces sleep in nocturnal mammals but wakefulness in diurnal ones, like humans. Therefore, the mechanisms through which light modulates affect and cognition must differ between the chronotypes. To further understand the neural pathways mediating how ambient light modulates affect and cognition, our recent work has developed a diurnal rodent model, the Nile grass rat (Arvicanthis niloticus), in which daytime light intensity is chronically manipulated in grass rats housed under the same 12:12 hour light/dark cycle. This simulates lighting conditions during summer-like bright sunny days vs. winter-like dim cloudy days. Our work has revealed that chronic dim daylight intensity results in higher depression- and anxiety-like behaviors, as well as impaired spatial learning and memory. Furthermore, we have found that hypothalamic orexin is a mediator of these effects. A better understanding of how changes in daytime light intensity impinge upon the neural substrates involved in affect and cognition will lead to novel preventive and therapeutic strategies for seasonal affective disorder, as well as for non-seasonal emotional or cognitive impairments associated with light deficiency.

[Seasons, circadian rhythms, sleep and suicidal behaviors vulnerability]

INTRODUCTION

Suicidal behaviors are common in the general population and are so a major public health problem. In order to improve suicide prevention and to reduce the mortality by suicide, it appears essential to better identify suicide risk factors. Seasonality, circadian rhythms and sleep abnormalities have been already associated with numerous psychiatric disorders. This review aimed to characterize the associations between seasonality, circadian rhythms, sleep and suicidal behaviors including suicide attempts and completed suicides.

METHODS

We conducted a literature search between 1973 and 2015 in PubMed databases using the following terms: ("suicide" OR "suicidality" OR "suicide attempts" OR "suicidal behavior") AND ("circadian rhythms" OR "seasons" OR "sleep").

RESULTS

Many studies confirm a specific seasonality for suicide with a higher peak of suicides in spring for both sex and a lower peak in autumn especially for women. This distribution seems to correlate with depressive symptoms (especially for the autumn peak), gender and different types of suicide. Regarding gender and type of suicide differences, males more commonly commit violent suicide with a higher rate of suicides in spring. Suicide behaviors appear to be influenced by climatic and biological factors like sunshine, daylight cycles, temperature, air pollutants, viruses, parasites and aeroallergens. Circadian variations exist in suicide rates depending on age with a morning peak for elder and an evening peak for youth. In addition, completed suicide peak in early morning whereas suicide attempts peak rather in later afternoon. Several biomarkers dysregulation like melatonin, serotonin and cortisol may be implicated in suicide circadian variations. Furthermore, specific sleep disorders like insomnia, nightmares and sleep deprivation are common risk factors of suicide and possibly independently of the presence of depressive symptoms. Finally, the efficacy of chronotherapeutics (such as luminotherapy, dark therapy, sleep deprivation and melatonin drugs) has been suggested in the reduction of suicidal behaviors.

CONCLUSION

The suicide seasonality is very well documented showing a main peak in spring and another one in autumn. A suicide circadian distribution also exists depending of the suicidal behavior intensity and of the age. Numerous sleep disorders are also suicide risk factors and can be treated with chronotherapeutics. A better identification of seasonality, circadian rhythms and sleep abnormalities in suicidal behaviors could allow a better prevention in suicidal attempts and a reduction in death by suicide.

Seasonality and its distinct clinical correlates in bipolar II disorder

Seasonality is one of the key features in subjects with mood disorders and is involved in the multi-faceted nature of the clinical course. However, few studies have explored the clinical implications of seasonality in bipolar disorders. We examined the differential effects of seasonality on clinical variables between bipolar I and II disorder (BD I and II). Seasonality was assessed using the Seasonal Pattern Assessment Questionnaire (SPAQ) in 204 subjects with BD I and 308 with BD II. Following the comparisons between BD I and II groups, clinical characteristics related to seasonality were explored. Next, to predict the presence of seasonality, a logistic regression model was applied. The global seasonality score on the SPAQ was significantly higher in the BD II group than in the BD I group. In the BD I group, seasonality was associated with suicide attempt history. In the BD II group, on the other hand, seasonality was associated with female gender, depressive predominance, and premenstrual dysphoric disorder (PMDD). In the regression models, the presence of PMDD and female gender was significantly associated with seasonality in the BD II group. Our findings suggest that high seasonality tendency, a vulnerability maker for cyclic worsening, may contribute to a differential pattern of clinical characteristics in BD II.

Frequency and characteristics of individuals with seasonal pattern among depressive patients attending primary care in France

OBJECTIVE

High rates of bipolar disorder (BD) have been found among major depressives with seasonal pattern (SP) consulting in psychiatric departments, as well as among patients seeking primary care. As SP was reported to be common in the latter, the current study was designed to assess (a) the frequency and characteristics of SP among major depressives attending primary care and (b) the prevalence and aspects of BD in this population.

METHODS

Among 400 patients who consulted French general practitioners (GPs) for major depression between February and December 2010, 390 could be included in the study: 167 (42.8%) met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for seasonal pattern [SP(+)], whereas 223 (57.2%) did not meet these criteria [SP(-)]. The two groups were compared on demographic, clinical, family history and temperamental characteristics.

RESULTS

Compared to SP(-), SP(+) patients were more frequently female, married and with a later age at first depressive episode, and showed more atypical vegetative symptoms, comorbid bulimia and stimulant abuse. They also exhibited more lifetime depressive episodes, were more often diagnosed as having BD II and met more often bipolarity specifier criteria, with higher rates of bipolar temperaments and a higher BD family loading. Among SP(+) patients, 68.9% met the bipolarity specifier criteria, whereas 31.1% did not. Seasonality was not influenced by climatic conditions. The following independent variables were associated with SP: BD according to bipolarity specifier, female gender, comorbid bulimia nervosa, hypersomnia, number of depressive episodes and family history of substance abuse.

CONCLUSIONS

Seasonal pattern is frequent among depressive patients attending primary care in France and may be indicative of hidden bipolarity. Given the risks associated with both SP and bipolarity, GPs are likely to have a major role in regard to prevention.

Repeated exposure to conditioned fear stress increases anxiety and delays sleep recovery following exposure to an acute traumatic stressor

Repeated stressor exposure can sensitize physiological responses to novel stressors and facilitate the development of stress-related psychiatric disorders including anxiety. Disruptions in diurnal rhythms of sleep-wake behavior accompany stress-related psychiatric disorders and could contribute to their development. Complex stressors that include fear-eliciting stimuli can be a component of repeated stress experienced by human beings, but whether exposure to repeated fear can prime the development of anxiety and sleep disturbances is unknown. In the current study, adult male F344 rats were exposed to either control conditions or repeated contextual fear conditioning for 22 days followed by exposure to no, mild (10), or severe (100) acute uncontrollable tail shock stress. Exposure to acute stress produced anxiety-like behavior as measured by a reduction in juvenile social exploration and exaggerated shock-elicited freezing in a novel context. Prior exposure to repeated fear enhanced anxiety-like behavior as measured by shock-elicited freezing, but did not alter social exploratory behavior. The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress. Interestingly, exposure to acute stress reduced rapid eye movement (REM) and non-REM (NREM) sleep during the hours immediately following acute stress. This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep/wake behavior. Prior repeated fear extended the acute stress-induced REM and NREM sleep loss, impaired REM rebound, and prolonged the flattening of the diurnal rhythm of NREM sleep following acute stressor exposure. These data suggest that impaired recovery of sleep/wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.

Antepartum depression severity is increased during seasonally longer nights: relationship to melatonin and cortisol timing and quantity

Current research suggests that mood varies from season to season in some individuals, in conjunction with light-modulated alterations in chronobiologic indices such as melatonin and cortisol. The primary aim of this study was to evaluate the effects of seasonal variations in darkness on mood in depressed antepartum women, and to determine the relationship of seasonal mood variations to contemporaneous blood melatonin and cortisol measures; a secondary aim was to evaluate the influence of seasonal factors on measures of melancholic versus atypical depressive symptoms. We obtained measures of mood and overnight concentrations of plasma melatonin and serum cortisol in 19 depressed patients (DP) and 12 healthy control (HC) antepartum women, during on-going seasonal variations in daylight/darkness, in a cross-sectional design. Analyses of variance showed that in DP, but not HC, Hamilton Depression Rating Scale (HRSD) scores were significantly higher in women tested during seasonally longer versus shorter nights. This exacerbation of depressive symptoms occurred when the dim light melatonin onset, the melatonin synthesis offset, and the time of maximum cortisol secretion (acrophase) were phase-advanced (temporally shifted earlier), and melatonin quantity was reduced, in DP but not HC. Serum cortisol increased across gestational weeks in both the HC and DP groups, which did not differ significantly in cortisol concentration. Nevertheless, serum cortisol concentration correlated positively with HRSD score in DP but not HC; notably, HC showed neither significant mood changes nor altered melatonin and cortisol timing or quantity in association with seasonal variations. These findings suggest that depression severity during pregnancy may become elevated in association with seasonally related phase advances in melatonin and cortisol timing and reduced melatonin quantity that occur in DP, but not HC. Thus, women who experience antepartum depression may be more susceptible than their nondepressed counterparts to phase alterations in melatonin and cortisol timing during seasonally longer nights. Interventions that phase delay melatonin and/or cortisol timing-for example, increased exposure to bright evening light-might serve as an effective intervention for antepartum depressions whose severity is increased during seasonally longer nights.

Psychiatric and addictive symptoms of young adult female indoor tanners

PURPOSE

Indoor tanning (IT) increases risk for melanoma and is particularly common among young adult women. IT has also been linked with some psychiatric symptoms, and frequent tanning may indicate tanning dependence (addiction) associated with endorphin release during ultraviolet radiation exposure. The objective of the current study was to investigate associations between IT, tanning dependence, and psychiatric and substance use symptoms in young adult women.

DESIGN

Cross-sectional survey and psychiatric interview.

SETTING

Online, except for the Mini International Neuropsychiatric Interview (MINI), which was completed over the telephone.

SUBJECTS

Participants were 306 female university students aged 18 to 25 years.

MEASURES

MINI, Seasonal Scale Index, tanning dependence scales, reporting ever having used a tanning bed or booth with tanning lamps (single item), reporting smoking a cigarette in the last 30 days (single item).

ANALYSIS

Descriptive statistics, χ(2) analysis, multivariate logistic regression.

RESULTS

Forty-six percent of the sample reported a history of IT, and 25% were classified as tanning dependent. Multivariate logistic regression analyses showed that IT was significantly associated with symptoms of alcohol use disorders, generalized anxiety, and not having social anxiety. Tanning dependence was associated with symptoms of alcohol use disorders.

CONCLUSION

Tanning is of concern not only for its association with skin cancer but for its association with psychiatric and substance use symptoms. Young women with certain psychological problems may seek relief from their symptoms by IT. These findings suggest that indoor tanners may benefit from health behavior and other psychosocial interventions.

Responses of brain and behavior to changing day-length in the diurnal grass rat (Arvicanthis niloticus)

Seasonal affective disorder (SAD) is a major depressive disorder that recurs in the fall and winter when day-length gets short. It is well accepted that day-length is encoded by the principal circadian clock located in the suprachiasmatic nucleus (SCN), but very little is known about day-length encoding in diurnal mammals. The present study utilized the grass rat, Arvicanthis niloticus, to investigate how the circadian system responds to photoperiodic changes in a diurnal mammal that shows day-length-dependent mood changes. The animals were initially housed in equatorial day-length (12h, EP) followed by either long (16h, LP) or short (8h, SP) photoperiods. The LP animals showed an expansion of the peak phase of the PER1 and PER2 rhythm in the SCN as well as an extended behavioral active phase. In contrast, the SP animals did not show any compression of their active phase nor a change in the peak duration of PER1 or PER2 expression, compared to those in EP. The results suggest that the circadian system in the diurnal grass rats is less responsive when day-length gets short compared to when it gets longer. The depression-like behaviors were assessed using sweet solution preference (SSP) and forced swimming test (FST). Animals in the SP group showed decreased SSP and increased immobility time in FST as compared to the EP group, suggesting a depressive phenotype. The present study serves as the first step toward exploring the role that the circadian system plays in SAD using a diurnal rodent model.

Is there a negative impact of winter on mental distress and sleeping problems in the subarctic: the Tromsø Study

BACKGROUND

Prior studies have suggested that the darkness of winter impacts the level of mental distress and sleeping problems. Our study investigated whether people living in the sub-arctic had more sleeping problems or mental distress during winter.

METHODS

The cross sectional population Tromsø Study was conducted in Tromsø, North Norway, at 69.4 degrees North and above the Arctic Circle. The study included entire birth cohorts and random samples of the population aged 30 to 87 years. Data was collected continuously from 1 October 2007 to the end of December 2008 except July. 8951 persons completed questionnaires including the HSCL-10 and the MCTQ.

RESULTS

There were no significant differences in the reporting of current mental distress depending on season. Significantly more reported current sleeping problems in winter than in the other seasons, and less sleeping problems was found in spring.

CONCLUSIONS

In this sub-arctic population, insomnia was most prevalent in winter, but there were no significant seasonal differences in mental distress. Although some people in the sub-arctic clearly are mentally negatively affected by the darkness of winter, the negative impact of winter on mental distress for the adult population is not conclusive.

Meta-review of depressive subtyping models

BACKGROUND

Increasing dissatisfaction with the non-specificity of major depression has led many to propose more specific depressive subtyping models. The present meta-review seeks to map dominant depressive subtype models, and highlight definitions and overlaps.

METHODS

A database search in Medline and EMBASE of proposed depressive subtypes, and limited to reviews published between 2000 and 2011, was undertaken. Of the more than four thousand reviews, 754 were judged as potentially relevant and provided the base for the present selective meta-review.

RESULTS

Fifteen subtype models were identified. The subtypes could be divided into five molar categories of (1) symptom-based subtypes, such as melancholia, psychotic depression, atypical depression and anxious depression, (2) aetiologically-based subtypes, exemplified by adjustment disorders, early trauma depression, reproductive depression, perinatal depression, organic depression and drug-induced depression, (3) time of onset-based subtypes, as illustrated by early and late onset depression, as well as seasonal affective disorder, (4) gender-based (e.g. female) depression, and (5) treatment resistant depression. An overview considering definition, bio-psycho-social correlates and the evidence base of treatment options for each subtype is provided.

LIMITATIONS

Despite the large data base, this meta-review is nevertheless narrative focused.

CONCLUSIONS

Subtyping depression is a promising attempt to overcome the non-specificity of many diagnostic constructs such as major depression, both in relation to their intrinsic non-specificity and failure to provide treatment-specific information. If a subtyping model is to be advanced it would need, however, to demonstrate differential impacts of causes and treatments.

The association between sunshine duration and paroxetine response time in patients with major depressive disorder

INTRODUCTION

A recent study indicates that the serotonin transporter function varies with the duration of monthly sunshine. This finding may suggest that the efficacy of serotonin selective reuptake inhibitors (SSRIs) is associated with the duration of monthly sunshine, but information on this possible association is lacking.

METHODS

Ninety-one Japanese subjects with depression completed a 6-week treatment with paroxetine. Clinical evaluation was performed using the Montgomery and Asberg Depression Rating Scale (MADRS) before treatment and after 1, 2, 4 and 6 weeks of treatment. Data on the duration of monthly sunshine were obtained from the meteorological agency website. We divided the patients into four groups: nonresponders (NRs), later responders (LRs), early responders (ERs) and ultra-early responders (UERs).

RESULTS

The responses to paroxetine treatment of the group that began treatment in fall and winter and of the group that began treatment in spring and summer did not differ significantly. The effect of the duration of monthly sunshine on paroxetine response time did not differ significantly among the four groups, whereas the change in the duration of monthly sunshine had a significant effect on paroxetine response time.

LIMITATIONS

Our sample of patients with MDD was small and only included the Hirosaki area.

CONCLUSION

The change in the duration of monthly sunshine is associated with paroxetine response time.

Circadian rhythms and mood regulation: insights from pre-clinical models

Affective disorders such as major depression, bipolar disorder, and seasonal affective disorder are associated with major disruptions in circadian rhythms. Indeed, altered sleep/wake cycles are a critical feature for diagnosis in the DSM IV and several of the therapies used to treat these disorders have profound effects on rhythm length and stabilization in human populations. Furthermore, multiple human genetic studies have identified polymorphisms in specific circadian genes associated with these disorders. Thus, there appears to be a strong association between the circadian system and mood regulation, although the mechanisms that underlie this association are unclear. Recently, a number of studies in animal models have begun to shed light on the complex interactions between circadian genes and mood-related neurotransmitter systems, the effects of light manipulation on brain circuitry, the impact of chronic stress on rhythms, and the ways in which antidepressant and mood-stabilizing drugs alter the clock. This review will focus on the recent advances that have been gleaned from the use of pre-clinical models to further our understanding of how the circadian system regulates mood.

Therapeutic armamentarium for treating depression

Depressive disorders are highly prevalent and are a leading cause of disability, morbidity, and mortality worldwide; however, they often remain undertreated or untreated. This article provides a broad overview of the many strategies for treating depression. More than 24 antidepressant medications and depression-focused psychotherapies are available as first-choice options for treating depression. When patients have not had a satisfactory treatment response, the 2 main strategies are switching to an alternative antidepressant therapy or adding a second antidepressant therapy. A large number of medication combinations have been reported in the literature, and some have been shown to be effective in controlled studies. Nonstandard alternatives to conventional antidepressant treatments include exercise, light therapy, sleep deprivation, and various complementary and alternative therapies. For more chronic and refractory forms of depression, various neuromodulation therapies are available or are being investigated. Because depressive disorders are common in primary care and other medical settings, medical practitioners should be aware of the therapeutic armamentarium available for treating depression.

Critical appraisal and update on the clinical utility of agomelatine, a melatonergic agonist, for the treatment of major depressive disease in adults

This article describes the pharmacology of the novel atypical antidepressant drug agomelatine, critically reviews and evaluates its clinical use for the treatment of major depression, and suggests areas for further research. Agomelatine is a synthetic analog of the hormone melatonin. It stimulates the activity of melatonin MT1 and MT2 receptors and inhibits the activity of serotonin 5HT-2C receptor subtypes. Three acute trials demonstrated clinically modest, but statistically significant benefits over placebo. Three acute trials did not find agomelatine more effective than placebo. A meta-analysis of these six trials demonstrated a small, statistically significant, marginally clinically relevant difference between agomelatine and placebo. The only placebo-controlled study in elderly patients did not demonstrate a significant benefit for agomelatine. It was more effective than placebo in only one of two relapse prevention studies. Agomelatine was generally well tolerated compared to placebo. Its side-effect profile is different than and compares favorably to other antidepressant drugs. The overall tolerability of agomelatine in head-to-head comparisons was not substantially better than active drug comparators. Agomelatine is contraindicated in patients with impaired liver function and in patients taking drugs that potently inhibit CYP-1A2 metabolic enzymes. Because elevated liver enzymes are common, and there is a rare risk of more serious liver reactions, routine laboratory monitoring of liver function is recommended periodically throughout treatment. Agomelatine does not have clinically significant advantages compared to other antidepressant drugs, and it has certain limitations and disadvantages. Because of its unique pharmacology and relatively benign tolerability profile, however, it may be a useful alternative for patients who do not respond to or cannot tolerate other antidepressant drugs.