Influence of season and latitude in a community sample of subjects with bipolar disorder

Association of the intronic rs2072621 polymorphism of the X-linked GPR50 gene with affective disorder with seasonal pattern

This case-control study found an association between Seasonal Affective Disorder (SAD) and a single nucleotide polymorphism (intronic rs2072621) of the gene encoding GPR50 (an orphan member of the G protein-coupled melatonin receptor subfamily) in females. This may represent a gender-specific risk factor and a molecular link between melatonin and SAD.

Animal models for bipolar disorder: from bedside to the cage

Bipolar disorder is characterized by recurrent manic and depressive episodes. Patients suffering from this disorder experience dramatic mood swings with a wide variety of typical behavioral facets, affecting overall activity, energy, sexual behavior, sense of self, self-esteem, circadian rhythm, cognition, and increased risk for suicide. Effective treatment options are limited and diagnosis can be complicated. To overcome these obstacles, a better understanding of the neurobiology underlying bipolar disorder is needed. Animal models can be useful tools in understanding brain mechanisms associated with certain behavior. The following review discusses several pathological aspects of humans suffering from bipolar disorder and compares these findings with insights obtained from several animal models mimicking diverse facets of its symptomatology. Various sections of the review concentrate on specific topics that are relevant in human patients, namely circadian rhythms, neurotransmitters, focusing on the dopaminergic system, stressful environment, and the immune system. We then explain how these areas have been manipulated to create animal models for the disorder. Even though several approaches have been conducted, there is still a lack of adequate animal models for bipolar disorder. Specifically, most animal models mimic only mania or depression and only a few include the cyclical nature of the human condition. Future studies could therefore focus on modeling both episodes in the same animal model to also have the possibility to investigate the switch from mania-like behavior to depressive-like behavior and vice versa. The use of viral tools and a focus on circadian rhythms and the immune system might make the creation of such animal models possible.

Pupillary response abnormalities in depressive disorders

Depressive disorders lack objective physiological measurements to characterize the affected population and facilitate study of relevant mechanisms. The melanopsin-mediated light signaling pathway may contribute to seasonal variation and can be measured non-invasively by pupillometry. We prospectively studied changes in melanopsin-mediated pupillary constriction in 19 participants with major depressive disorder (MDD) and 10 control across the summer and winter solstices. The melanopsin-mediated response, as measured by the pupil's sustained constriction six s after a high intensity blue light stimulus, was marginally attenuated in those with MDD relative to controls (p=0.071). The participants with MDD unexpectedly showed a significantly reduced transient pupillary response to low intensity red (p=0.011) and blue light (p=0.013), but not high intensity red and blue light. Sustained pupillary constriction in response to high intensity blue light was more pronounced with increasing daylight hours (p=0.037) and was more strongly related to objectively measured versus estimated light exposure. Melanopsin-mediated impairments in pupil response may serve as a biological marker for vulnerability to depression in low light conditions. Assessment of these and other responses to light stimuli, such as response to low intensity light, may be useful for the study of the neurobiology of MDD and related mood disorders.

Serotonin transporter binding is reduced in seasonal affective disorder following light therapy

OBJECTIVE

To investigate the effects of light therapy on serotonin transporter binding (5-HTT BP_ND ), an index of 5-HTT levels, in the anterior cingulate and prefrontal cortices (ACC and PFC) during winter in seasonal affective disorder (SAD). 5-HTT BP_ND fluctuates seasonally to a greater extent in SAD relative to health. We hypothesized that in SAD, 5-HTT BP_ND would be reduced in the ACC and PFC following light therapy.

METHODS

Eleven SAD participants underwent [¹¹ C] DASB positron emission tomography (PET) scans to measure 5-HTT BP_ND before and after 2 weeks of daily morning light therapy.

RESULTS

The primary finding was a main effect of treatment on 5-HTT BP_ND in the ACC and PFC (repeated-measures manova, F_(2,9) = 6.82, P = 0.016). This effect was significant in the ACC (F_(1,10) = 15.11 and P = 0.003, magnitude of decrease, 11.94%) and PFC (F_(1,10) = 8.33, P = 0.016, magnitude of decrease, 9.13%). 5-HTT BP_ND also decreased in other regions assayed following light therapy (repeated-measures manova, F_(4,7) = 8.54, P = 0.028) including the hippocampus, ventral striatum, dorsal putamen, thalamus and midbrain (F_(1,10) = 8.02-36.94, P < 0.0001-0.018; magnitude -8.83% to -16.74%).

CONCLUSIONS

These results demonstrate that light therapy reaches an important therapeutic target in the treatment of SAD and provide a basis for improvement of this treatment via application of [¹¹ C]DASB PET.

Seasonal variations in rates of hospitalisation for mania and hypomania in psychiatric hospitals in NSW

BACKGROUND

A number of studies have established that manic patients have higher rates of hospitalization in spring. There appears to be no data evaluating whether there is any seasonal variation in hospitalization for those with hypomania.

METHODS

Data were obtained for 27,255 individuals hospitalized in NSW psychiatric hospitals over a 14-year period (2000-2014) for ICD-10 diagnosed mania or hypomania. Graphical analyzes examined rates of hospitalisation for hypomania and mania separately, using monthly and seasonal averages.

RESULTS

Admission rates were higher for mania compared to hypomania and there was a similar pattern across seasons - with admissions being at their lowest in autumn, increasing in winter, and at their highest for spring. Monthly percentage scores were similar for mania and hypomania and indicated lower admission rates in the first six months of the year (January-June), with a sudden increase in July, and followed by a more gradual increase until December.

LIMITATIONS

Hospitalization rates do not necessarily provide an accurate estimate of the onset of hypo/manic episodes, while the validity of those assigned a diagnosis of hypomania could not be established, allowing the possibility that many may have had manic episodes.

CONCLUSIONS

Findings indicate that hypomania shows a similar seasonal pattern to mania.

Seasonal pattern of manic episode admissions among bipolar I disorder patients is associated with male gender and presence of psychotic features

BACKGROUND

Bipolar I disorder (BD-I) patients demonstrate disrupted chronobiology expressed as seasonal variation in mood symptoms. The seasonal pattern (SP) specifier of mood disorders was recently extended by the DSM-5, to be applied to manic episodes. However, the significance of seasonality of manic episodes for the course of BD-I is unknown. In the present study we sought to identify clinical and demographic features that discriminate between BD-I patients with and without SP of manic admissions.

METHODS

BD-I patients (n=148) admitted at least twice with the same mood exacerbation type, were retrospectively followed between 2005 and 2013. Demographic and clinical characteristics were compared between BD-I patients with or without SP of manic admissions.

RESULTS

SP of manic episode admissions, found in 31 (26%) of 117 BD-I patients with repeated manic episode admissions, was associated with higher rates of male gender (p=0.01), presence of psychotic features (p=0.01) and comorbid substance use disorder (p<0.05) compared to patients without SP. In a multivariate analysis, SP of manic episode admissions was associated with the presence of psychotic features (OR 8.42, 95% CI: 1.05-67.65, p<0.05) and male gender (OR 3.23, 95% CI: 1.08-9.65, p<0.05), but not with comorbidity of substance use disorder (OR 1.79, 95% CI: 0.71-4.50, p=0.24).

LIMITATIONS

Seasonal psychological/environmental factors contributing to the emergent of mood episodes could not be ruled out.

CONCLUSIONS

Our results suggest that SP of manic admissions is associated with male gender and the presence of psychotic features, thus might be associated with more severe form of the disorder.

Seasonality of Admissions for Mania: Results From a General Hospital Psychiatric Unit in Pondicherry, India

INTRODUCTION

Bipolar disorder is affected by variables that modulate circadian rhythm, including seasonal variations. There is evidence of a seasonal pattern of admissions of mania in various geographical settings, though its timing varies by region and climate. Variables such as age and gender have been shown to affect seasonality in some studies.

METHODOLOGY

Data on monthly admission patterns for mania at a general hospital psychiatry unit in Pondicherry, India, were collected for 4 years (2010-2013) and analyzed for seasonality and seasonal peaks. The effects of age and gender were analyzed separately.

RESULTS

There was overall evidence of a seasonal pattern of admissions for mania (P < .01, Friedman test for seasonality), with a peak beginning during the rainy season and ending before summer (P < .0.1, Ratchet circular scan test). Male sex (P < .005, Ratchet circular scan test) and age > 25 years (P < .005, Ratchet circular scan test) were specifically associated with this seasonal peak.

DISCUSSION

The effect of seasons on mania is complex and is modulated by a variety of variables. Our study is consistent with earlier research findings: a greater degree of seasonality for mania in men. It is possible that climatic and individual variables interact to determine seasonal patterns in bipolar disorder in a given setting.

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.

Seasonality and bipolar disorder: a systematic review, from admission rates to seasonality of symptoms

INTRODUCTION

Bipolar disorder (BD) is a severe mental disorder affecting 1-4% of the population worldwide. It is characterized by periods of (hypo)manic and depressive episodes. Seasonal patterns (SP) may be observed in admission rates, mood relapses and symptom fluctuations.

METHODS

We conducted a systematic review of seasonality in BD, classifying studies based on seasonal admission rates to seasonality of symptoms assessments.

RESULTS

Fifty-one papers were identified of which 32 addressed hospitalization rates by season, 6 addressed categorical diagnoses, and 13 explored symptom dimensions. Seasonal peaks for different BD mood episodes are observed worldwide and widely replicated. Manic episodes peak during spring/summer and, to a lesser extent, in autumn, depressive episodes peak in early winter and, to a lesser extent, summer, and mixed episodes peak in early spring or mid/late summer. There was a high frequency of SP for manic episodes (15%) and depressive episodes (25%), the latter being associated with a more complex clinical profile (BD II subtype, comorbid eating disorders, more relapses and rapid cycling). Finally, there was evidence for greater seasonal fluctuations in mood and behavior in individuals with BD than in those with unipolar depression or 'healthy' controls.

LIMITATIONS

Sample size, gender distribution, methodological quality and sophistication of the analytical approaches employed varied considerably.

CONCLUSIONS

There is evidence of seasonality in BD, with emerging evidence that climatic conditions may trigger BD symptoms or episodes. A better understanding of the underlying mechanisms would facilitate the development of personalized chronobiological therapeutic and preventive strategies.

Bipolar disorder with seasonal pattern: clinical characteristics and gender influences

Bipolar disorder (BD) has a multifactorial etiology with heterogeneous clinical presentations. Around 25% of BD patients may present with a depressive seasonal pattern (SP). However, there are limited scientific data on the prevalence of SP, its clinical manifestations, and any gender influence. Four hundred and fifty-two BD I and II cases (62% female), recruited from three French university-affiliated psychiatric departments, were assessed for SP. Clinical, treatment, and sociodemographic variables were obtained from structured interviews. One hundred and two (23%) cases met DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) criteria for SP, with similar frequency according to gender. Multivariate analysis showed a significant association between SP and BD II (odds ratio [OR] = 1.99, p = 0.01), lifetime history of rapid cycling (OR = 2.05, p = 0.02), eating disorders (OR = 2.94, p = 0.003), and total number of depressive episodes (OR = 1.13, p = 0.002). Seventy-one percent of cases were correctly classified by this analysis. However, when stratifying the analyses by gender, SP was associated with BD II subtype (OR = 2.89, p = 0.017) and total number of depressive episodes (OR = 1.21, p = 0.0018) in males but with rapid cycling (OR = 3.02, p = 0.0027) and eating disorders (OR = 2.60, p = 0.016) in females. This is the first study to identify different associations between SP and clinical characteristics of BD according to gender. The authors suggest that SP represents a potentially important specifier of BD. These findings indicate that seasonality may reflect increased severity or complexity of disorder.

Evidence for seasonal mania: a review

OBJECTIVE

The goal of this article is to summarize the evidence for seasonal mania based on research studies and findings concerning interrelationships among circadian rhythm, manic episodes, and mood stabilizers.

METHODS

The PubMed database was searched using the key word "seasonal mania." This search generated a list of 197 papers published between 1990 and 2011, 29 of which were original research studies on seasonal mania. The findings from these studies were reviewed with regard to their relevance to the mechanisms involved in seasonal mania and strategies for managing mania.

RESULTS

Of the 29 research studies, the majority (n=23) provided evidence for a significant seasonal pattern for mania, while the other 6 studies did not. Most of the studies reported that mania occurred more often during spring and summer and that depression occurred more often during fall and winter. The authors of the studies estimated a prevalence of seasonal mania of 15% among patients with bipolar disorder. It is hypothesized that the underlying mechanism for seasonal mania may be hypersensitivity to bright light that suppresses melatonin production. Both lithium and valproate can counteract the action of bright light in suppressing melatonin and prolong sleep-wake cycles in the circadian rhythms of patients with bipolar disorder. These effects may at least partially explain their efficacy as mood stabilizing agents. No research studies were located that provided information on managing the medication regimen, especially of mood stabilizing medications, based on the seasonal patterns seen in some patients with bipolar disorder in order to reduce the risk of relapse associated with seasonal mania. Positive findings in this area might lead to a new paradigm for the management of patients with bipolar disorder who have seasonal mania.

The relationship between bipolar disorder, seasonality, and premenstrual symptoms

Cyclical mood disorders characterized by shifting affective states include bipolar disorder, seasonal affective disorder, and premenstrual syndrome/premenstrual dysphoric disorder. In this article, we explore the relationship between these disorders and bring the reader up to date on the advances made in the past year in understanding the relationship between bipolar disorder, seasonality, and premenstrual symptoms.

Evolutionary origin of bipolar disorder-revised: EOBD-R

The hypothesis of the evolutionary origin of bipolar disorder (EOBD) synthesized ideas about the biological clock and seasonal shifts in mood (Rosenthal, Wehr) with theorizing that bipolar disorder descends from a pyknic (compact, cold-adapted) group (Kretchmer). The hypothesis suggested that bipolar behaviors evolved in the northern temperate zone as highly derived adaptations to the selective pressures of severe climatic conditions during the Pleistocene. Given evidence of Neandertal contributions to the human genome, the hypothesis is extended (EOBD-R) to suggest Neandertal as the ancestral source for bipolar vulnerability genes (susceptibility alleles). The EOBD-R hypothesis explains and integrates existing observations: bipolar disorder has the epidemiology of an adaptation; it is correlated with a cold-adapted build, and its moods vary according to light and season. Since the hypothesis was first published, data consistent with it have continued to appear. Individuals with seasonal affective disorder, which is related to bipolar disorder, have been shown to manifest a biological signal of season change similar to that found in hibernating animals. The involvement of the circadian gene network in the pathophysiology of bipolar disorder has been confirmed. Because selective pressures during the Pleistocene would have been greatest for women of reproductive age, they are expected to manifest winter depression more than males or younger females, which is the case. (This sex difference is also found in hibernating mammals.) Because it is hypothesized that the evolution of bipolar disorder took place in the northern temperate zone during the Pleistocene, it is not expected that individuals of African descent, lacking Neandertal genes, will manifest circular bipolar I disorder, and in fact, the incidence of bipolar disorder among black individuals is less than among whites. A definitive test of the hypothesis is proposed: It is predicted that the bipolar and Neandertal genomes will be more similar than the modern human and Neandertal genomes, and the modern human and San and Yoruba genomes will be more similar than the bipolar and San and Yoruba genomes. Failure to confirm these predictions will falsify the EOBD-R hypothesis. The EOBD-R hypothesis has important implications in the search for bipolar vulnerability genes and our understanding of ourselves and our Neandertal ancestor. At a practical level, confirmation of the EOBD-R hypothesis will boost interest and research in the prevention and management of bipolar symptoms by manipulation of ambient light.

Seasonal symptoms in bipolar and primary care patients

BACKGROUND

There is evidence of seasonality in bipolar affective disorder (BAD) and the preponderance of atypical symptoms in bipolar depressive episodes is also seen in winter type Seasonal Affective Disorder. Differences in seasonal symptoms between BAD and appropriate comparison populations have been scrutinised only in small studies.

METHODS

Symptoms described on the Seasonal Pattern Assessment Questionnaire (SPAQ) were compared between 183 patients with BAD and 468 patients consulting their general practitioners. Statistical analyses were adjusted for differing age and gender distributions between the two groups.

RESULTS

Compared with the general practice patients, subjects with BAD reported greater seasonal fluctuations in mood (p=0.003). On one measure BAD subjects reported increased seasonal changes in social activity (p<0.001) and greater weight fluctuation over the year (p=0.001). The most striking differences were in sleep patterns; BAD subjects slept significantly more throughout the year, and slept for a mean of 1.8h more in winter than in summer (versus a 1.0h difference in the general practice group, p<0.001). Against 20% of the general practice group, 46% of BAD patients rated seasonal changes in well-being to be at least a moderate problem.

LIMITATIONS

The SPAQ was designed as a screening instrument for Seasonal Affective Disorder, not for studies of this nature. Some of the reported differences, notably in social activity and weight changes, may reflect secondary psychosocial effects of BAD.

CONCLUSIONS

Seasonal changes, most notably winter hypersomnia, should be identified in patients with BAD. These symptoms may respond to treatments such as light therapy that are used in recurrent winter depression.

The seasonality of bipolar affective disorder: comparison with a primary care sample using the Seasonal Pattern Assessment Questionnaire

BACKGROUND

In contrast with recurrent unipolar depression, relatively little is known about the seasonality of depressive episodes in bipolar affective disorder (BAD).

METHOD

We compared responses on the Seasonal Pattern Assessment Questionnaire (SPAQ) between a cohort of 183 patients with BAD and a large sample of patients in primary care (N=4746). Comparisons were adjusted for age and gender.

RESULTS

27% of the BAD patients fulfilled SPAQ criteria for Seasonal Affective Disorder (SAD. This gave an adjusted odds ratio of 3.73 (95% confidence intervals 2.64 to 5.27) in comparison with the rate among the primary care samples. Global seasonality scores were significantly higher among BAD patients (adjusted mean difference 1.73, 95% CI 0.97 to 2.49, p<0.001).

LIMITATIONS

The SPAQ was originally designed as a screening instrument rather than as a case-finding instrument.

CONCLUSIONS

Vigilance for seasonal symptom recurrence in BAD may be important with regard to management and relapse prevention.

The delivery mode and seasonal variation are associated with the development of postpartum depression

INTRODUCTION

Previous studies have indicated that mode of delivery and/or season of delivery might be risk factors for postpartum depression (PD). However, only a few studies have provided support for this supposition. This study aim was to confirm the association between mode of delivery and/or season of delivery and PD.

METHODS

We analyzed 2003-2006 Taiwan National Health Insurance Research Database (NHIRD). A group of 2107 mothers who were diagnosed with PD within 6months of delivery in 2005 were selected as the case group and another 8428 mothers without PD during the same timeframe were selected as the control group. Logistic regression was performed after controlling for age, antepartum comorbidities and postpartum complications to confirm the degree of association with the risk of PD.

RESULTS

The results of the logistic regression analysis showed that the risk of acquiring PD was lower in mothers with a normal vaginal delivery or an instrumental vaginal delivery compared to mothers with an emergency caesarean section (odds ratio [OR]=0.67, p<0.0001; OR=0.56, p<0.0001). But the women who elected to have a caesarean section was higher risk than an emergency caesarean section (OR=1.48, p=0.0168). In addition, the risk of PD for winter deliveries was higher compared to other seasons.

CONCLUSIONS

This study provides a reference for gynecologists, obstetricians and health providers that should help with the prevention of PD among pregnant women and mothers.

The effect of seasons and seasonal variation on neuropsychological test performance in patients with bipolar I disorder and their first-degree relatives

BACKGROUND

Bipolar disorder (BD) patients have cognitive deficits that may remain in the euthymic phase. Similar although milder cognitive deficits may be found in their first-degree relatives. We wanted to analyze whether the self-report of seasonality, the season when individuals were tested or the circadian preference influences the neuropsychological test performance measured in the familial BD, type I, patients and their healthy first-degree relatives.

METHOD

A structured diagnostic interview (SCID) and neuropsychological test battery were administered to 32 familial BD type I patients, 40 of their unaffected first-degree relatives and 50 controls, all from population-based samples. BD patients and their relatives filled in the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Horne-Östberg Morningness-Eveningness Questionnaire (MEQ).

RESULTS

Individuals, who reported that seasonal variation was a problem, scored worse on the measures of visuoconstructional functions, visuospatial reasoning, auditory attention and working memory, and verbal memory than those with no seasonal variation. The season when tested had an influence on test performance. Individuals from the families that were tested in spring, summer and autumn scored better than those tested in winter on the measures of visual and verbal attention, working memory, verbal ability, verbal fluency, and executive functioning. Among the controls there was no difference in the test scores from season to season. The circadian preference had no effect on test performance.

LIMITATIONS

Only relatives, not BD patients were tested in winter.

CONCLUSION

Seasonal variation in mood and behavior as a problem in patients and their first-degree relatives influences negatively the neuropsychological test performance. In addition, among the patients and first-degree relatives the neuropsychological test performance in winter may be worse than in other seasons.

Relationship among latitude, climate, season and self-reported mood in bipolar disorder

OBJECTIVE

Many researchers have analyzed seasonal variation in hospital admissions for bipolar disorder with inconsistent results. We investigated if a seasonal pattern was present in daily self-reported daily mood ratings from patients living in five climate zones in the northern and southern hemispheres. We also investigated the influence of latitude and seasonal climate variables on mood.

METHOD

360 patients who were receiving treatment as usual recorded mood daily (59,422 total days of data). Both the percentage of days depressed and hypomanic/manic, and the episodes of depression and mania were determined. The observations were provided by patients from different geographic locations in North and South America, Europe and Australia. These data were analyzed for seasonality by climate zone using both a sinusoidal regression and the Gini index. Additionally, the influence of latitude and climate variables on mood was estimated using generalized linear models for each season and month.

RESULTS

No seasonality was found in any climate zone by either method. In spite of vastly different weather, neither latitude nor climate variables were associated with mood by season or month.

CONCLUSION

Daily self-reported mood ratings of most patients with bipolar disorder did not show a seasonal pattern. Neither climate nor latitude has a primary influence on the daily mood changes of most patients receiving medication for bipolar disorder.

Epidemiologic heterogeneity of common mood and anxiety disorders over the lifecourse in the general population: a systematic review

BACKGROUND

Clinical evidence has long suggested there may be heterogeneity in the patterns and predictors of common mood and anxiety disorders; however, epidemiologic studies have generally treated these outcomes as homogenous entities. The objective of this study was to systematically review the epidemiologic evidence for potential patterns of heterogeneity of common mood and anxiety disorders over the lifecourse in the general population.

METHODS

We reviewed epidemiologic studies examining heterogeneity in either the nature of symptoms experienced ("symptom syndromes") or in patterns of symptoms over time ("symptom trajectories"). To be included, studies of syndromes were required to identify distinct symptom subtypes, and studies of trajectories were required to identify distinct longitudinal patterns of symptoms in at least three waves of follow-up. Studies based on clinical or patient populations were excluded.

RESULTS

While research in this field is in its infancy, we found growing evidence that, not only can mood and anxiety disorders be differentiated by symptom syndromes and trajectories, but that the factors associated with these disorders may vary between these subtypes. Whether this reflects a causal pathway, where genetic or environmental factors influence the nature of the symptom or trajectory subtype experienced by an individual, or whether individuals with different subtypes differed in their susceptibility to different environmental factors, could not be determined. Few studies addressed issues of comorbidity or transitions in symptoms between common disorders.

CONCLUSION

Understanding the diversity of these conditions may help us identify preventable factors that are only associated with some subtypes of these common disorders.

Some new food for thought: the role of vitamin D in the mental health of older adults

Vitamin D, a multipurpose steroid hormone vital to health, has been increasingly implicated in the pathology of cognition and mental illness. Hypovitaminosis D is prevalent among older adults, and several studies suggest an association between hypovitaminosis D and basic and executive cognitive functions, depression, bipolar disorder, and schizophrenia. Vitamin D activates receptors on neurons in regions implicated in the regulation of behavior, stimulates neurotrophin release, and protects the brain by buffering antioxidant and anti-inflammatory defenses against vascular injury and improving metabolic and cardiovascular function. Although additional studies are needed to examine the impact of supplementation on cognition and mood disorders, given the known health benefits of vitamin D, we recommend greater supplementation in older adults.

Clinical and prognostic implications of seasonal pattern in bipolar disorder: a 10-year follow-up of 302 patients

BACKGROUND

More than 20% of bipolar patients may present with seasonal pattern (SP). Seasonality can alter the course of bipolar disorder. However, to date, long-term follow-up studies of bipolar patients presenting with SP are scarce. We present a 10-year follow-up study comparing clinical and demographic features of bipolar patients with and without SP.

METHOD

Three hundred and twenty-five bipolar I and II patients were followed up for at least 10 years. SP was defined according to DSM-IV criteria. Clinical variables were obtained from structured interviews with the patients and their relatives. Patients with and without SP were compared regarding clinical and sociodemographic variables and a stepwise logistic regression was performed.

RESULTS

Seventy-seven patients (25.5%) were classified as presenting with SP, while 225 (74.5%) were considered as presenting with no significant seasonal variation. Twenty-three patients (7%) were excluded from the study because it was unclear whether they had seasonality or not. There were no differences between groups regarding demographic variables. Patients with SP predominantly presented with bipolar II disorder, depressive onset, and depressive predominant polarity. The greater burden of depression did not correlate with indirect indicators of severity, such as suicidality, hospitalizations or psychotic symptoms.

CONCLUSIONS

Our study links the presence of SP with both bipolar II disorder and predominant depressive component. However, we could not find any difference regarding functionality or hospitalization rates. Modifications in the criteria to define SP are suggested for a better understanding of bipolar disorder.

Seasonal variations in bipolar disorder admissions and the association with climate: a population-based study

OBJECTIVE

Although seasonal influences on bipolar disorder admissions have long been observed, the issues of seasonality on different subtypes of mood episodes and the effects of associated climatic parameters remain controversial. This study sets out to examine seasonal variations in bipolar disorder admissions and the association with climate in Taiwan, a subtropical area with fairly constant weather conditions.

METHODS

This retrospective population-based study uses the Taiwan National Health Insurance Research Database for 1999-2003, identifying 15,060 admissions for bipolar disorder, comprising of 8631 manic, 2078 depressive and 4351 mixed/unspecified episodes. The auto-regressive integrated moving average model was applied to examine the presence of seasonality and the association with climate in each subtype of mood episodes.

RESULTS

Admission peaks were noted during spring/summer, early winter and early spring, for manic, depressive and mixed/unspecified episodes, respectively, while the associations with climatic parameters varied between the subtypes of mood episodes.

CONCLUSIONS

Seasonality in bipolar disorder does exist for all subtypes of mood episodes. The distinct seasonal patterns and various associations with the climatic parameters imply different underlying mechanisms for the onset of each subtype of mood episodes. The association between admission rates and certain climatic variables found in this study is informative and could pave the way for future studies aimed at exploring the influence of climate on the psychopathology of bipolar patients as well as the underlying mechanisms.

Seasonality in a community sample of bipolar, unipolar and control subjects

BACKGROUND

This study examined seasonality in a community sample of five diagnostic groups: normal subjects, those with non-seasonal depression (NSD), seasonal depression (SD), non-seasonal bipolar disorder (NSBD) and seasonal bipolar disorder (SBD).

METHODS

Telephone interviews were conducted across the Province of Ontario. Seasonal changes in mood and behaviour were determined using the Seasonal Pattern Assessment Questionnaire (SPAQ). Five additional seasonality items consisting of depressive symptoms were included in the interview. The mean global severity of seasonality (GSS) scores were obtained and the entire inventory of 11 seasonality items were compared across the identified groups.

RESULTS

The mean GSS score for the controls was 5.2 (S.D. = 4.0), 8.0 (S.D. = 4.9) for NSD, 10.5 (S.D. = 3.9) for SD, 10.5 (S.D. = 5.4) for NSBD and 13.4 (S.D. = 5.4) for SBD. These scores differed significantly (F = 61.68, df = 4, p < 0.001). For the majority of the individual items, the SBD group rated the highest degree of seasonal fluctuation, while the NSBD and SD groups had nearly identical item scores.

LIMITATIONS

Limitations in this study include the relatively small number of subjects in the NSBD and SBD groups, and the inherent limitations in a telephone interview.

CONCLUSIONS

Individuals with bipolar disorder experience greater seasonality than those with depression or healthy controls. Even the non-seasonal bipolar group had as much seasonal fluctuation as the seasonal depression group, which has important implications for the management of bipolar illness.