Seasonal variation of depressive symptoms in unipolar major depressive disorder
Introduction
Documentation of seasonal variation in mood states dates back to the time of Hippocrates. Evidence for this phenomenon ranges from prospective symptom tracking to retrospective interrogation with the Seasonal Patterns of Affective Disorders Questionnaire (SPAQ) to global Internet search patterns – all of which have reported seasonal mood patterns in patients and in the general population [1], [2], [3], [4], [5], [6]. This “seasonality” of mood seems to lie on a spectrum of severity [7], with the more extreme cases falling under the description of “seasonal affective disorder,” or SAD, as established by Rosenthal et al. in 1984 [8]. It has been estimated that in any given year, 5% of the U.S. population and up to 9.7% of the population in other countries may suffer from SAD [9], [10], while the prevalence of SAD in patients with major depression has been estimated at between 10 and 20% [10], suggesting greater seasonal mood fluctuation in those with unipolar major depressive disorder (MDD).
As the first criterion in Rosenthal's proposed definition of SAD is “A history of major affective disorder, according to the RDC” (Research Diagnostic Criteria) [8], an increased incidence of SAD within those with MDD is not only to be expected, but by at least this definition must be the case since those with syndromal depression cannot meet the Rosenthal criteria. However, much of the epidemiological data on SAD to date has been generated using the SPAQ, which assays seasonality independent of a mood disorder diagnosis. High scores could thus reflect seasonal variation in specific symptoms rather than changes in point prevalence of SAD, and the SPAQ may therefore overestimate the prevalence of MDD, seasonal pattern (MDD-SP) [1], [11], [12]. In fact, one study found that neither the Global Seasonality Score (GSS) nor the report of season change as a problem on the SPAQ predicted longitudinal mood ratings [13]. Other key limitations of the SPAQ include its retrospective and seasonality-specific nature, which subjects it to recall and measurement biases, respectively. Indeed, the SPAQ has been shown to exaggerate seasonal mood differences as compared to prospective assessments in certain populations [1].
To address these limitations in studying the seasonality of major depressive episodes, some have administered non-seasonality-specific mood assessments to depressed patient populations in a cross-sectional manner throughout the different seasons. The evidence of seasonality from these investigations – even within single studies – has been inconclusive. For example, data from the U.S. National Comorbidity Survey showed that 10–20% of people with MDD had symptoms that recurred at consistent times each year [11], but only 0.4% met strict Diagnostic and Statistical Manual (DSM) criteria for MDD-SP. Similarly, a study of 2225 general practice patients in London showed that while those with RDC major depression had significant peaks for episode onset in the winter and recovery in the summer [14], corresponding winter and summer changes in General Health Questionnaire scores did not cross the threshold of statistical significance.
Retrospective chart review was utilized to construct course of illness by Faedda et al., who applied DSM-III-R MDD-SP criteria to clinical records of 557 outpatients with recurrent depression. Over an average of 12 years of documented illness course, 75 (13.5%) with recurrent depression had a seasonal pattern [15], with high intra-individual stability in timing of depressive episode onset and remission. Based upon the large sample, longitudinal nature and substantial “follow-up” period, this study offers the most compelling current evidence of seasonal patterns in unipolar depression.
This finding was not replicated, however, in a similar setting. Posternak et al. retrospectively examined presentation patterns of 1500 consecutive patients at a Rhode Island outpatient psychiatric clinic and reported no significant seasonal changes in the rate of depressive symptoms or proportion of patients diagnosed with MDD [16]. Similarly, a large cross-sectional study in the Netherlands found no significant effect of season of administration on overall scores on the Inventory of Depressive Symptoms (IDS), though atypical and melancholic IDS scores were heightened during the winter [17]. Additionally, a study by Hardin et al. reported no significant difference between depressed patients and controls on SPAQ global seasonality scores [18].
The existing literature on seasonality in MDD is problematic not only due to these discordant results, but in that much of the research is cross-sectional or based on patterns of patient presentation or admission to health care facilities, and not on systematic, prospective follow-up. Those studies which have examined the same patients over a number of years are either retrospective or focused on individuals already diagnosed with SAD or recurrent depression-seasonal pattern to study illness course and diagnostic stability [19], [20], [21], [22]. Prospective studies are further limited by inadequate duration, small sample sizes and confounding effects of treatment. For example, Sakamoto et al., which offers the longest prospective look at SAD patients with a mean follow-up of 6 years, did not systematically control for treatment and included only 25 patients, analyzing those with bipolar disorder and unipolar major depression together [19].
In sum, the degree to which patients with unipolar major depression experience varying symptom severity coincidental with the changing seasons has not been adequately examined in a prospective manner over an extended period using a standardized, non-seasonality-specific assessment. We sought to assess the monthly burden of clinically significant depressive symptoms over long-term follow-up in a clinical sample with unipolar MDD. Although some studies report spring and/or fall peaks in depression onset [15], [23], most of the literature on MDD-SP and SAD suggests that depressive symptoms are worst in the winter (variably defined in different studies as spanning November or December through January or February), at least in certain subgroups [1], [2], [3], [14], [24], [25], [26], [27], [28]; this encompasses a wide range of data, including hospital admission rates, SPAQ responses and standardized mood assessments. Thus, we hypothesized that those with MDD would have a peak in depressive symptomatology in the months surrounding the winter solstice (e.g. November, December, January), which would be consistent with our findings in bipolar disorder [29]. Lastly, we attempted to identify whether this pattern would persist over 20 years of follow-up.
Section snippets
Participants
The CDS included individuals with mood disorders from the following academic centers: Harvard University (Boston), Rush Presbyterian-St. Luke's Medical Center (Chicago), University of Iowa (Iowa City), New York State Psychiatric Institute and Columbia University (New York City), and Washington University School of Medicine (St. Louis). Participants were European-American (genetic hypotheses were tested), spoke English, had an IQ score of at least 70, and no evidence of terminal medical illness
Results
Our sample included 298 participants with unipolar major depression and was predominantly female (63%) as shown in Table 3. When contrasted to the 174 participants with a prospective diagnosis of unipolar major depression who did not complete 10 years of follow-up, our sample was more likely to be female (χ2 = 6.2, df = 1, p = 0.01) and less likely to have a diagnosis of alcoholism at intake (χ2 = 8.0, df = 1, p < 0.01). They also tended to have a younger age of onset (26.7 vs. 32.1 years, Wilcoxon Z = 3.4, p <
Discussion
In the present study we found that, on average, participants with unipolar major depression spent a greater proportion of time depressed in the months surrounding the winter solstice, though this difference only reached significance when using the post hoc December–April seasonal indicator. Statistics for the December–April indicator are subsequently best framed as hypothesis-generating and the observed peak was considered most appropriate for the assessment of the long-term stability of
Acknowledgment
This study was funded by NIMH grants 5R01MH025416-33 (W Coryell), 5R01MH023864-35 (J Endicott), 5R01MH025478-33 (M Keller), 5R01MH025430-33 (J Rice), and 5R01MH029957-30 (WA Scheftner). Dr. Fiedorowicz is supported by the National Institutes of Health (1K23MH083695-01A210).
Dr. Solomon serves as Deputy Editor to UpToDate.com. Dr. Keller has served as a consultant or received honoraria for CENEREX, Medtronic, and Sierra Neuropharmaceuticals. He has received grant/research support from Pfizer. He
References (48)
- et al.
The prevalence of seasonal affective disorder in The Netherlands: a prospective and retrospective study of seasonal mood variation in the general population
Biol Psychiatry
(1999) The Seasonal Pattern Assessment Questionnaire as a measure of mood seasonality: a prospective validation study
Psychiatry Res
(2003)- et al.
Seasonality prevalence and incidence of depressive disorder in a general practice sample: identifying differences in timing by caseness
J Affect Disord
(1997) - et al.
Lack of association between seasonality and psychopathology in psychiatric outpatients
Psychiatry Res
(2002) - et al.
Evaluation of seasonality in six clinical populations and two normal populations
J Psychiatr Res
(1991) - et al.
Long-term follow-up of depression in seasonal affective disorder
Compr Psychiatry
(1994) - et al.
Distinct seasonality of depressive episodes differentiates unipolar depressive patients with and without depressive mixed states
J Affect Disord
(2006) - et al.
Seasonality in major depressed inpatients
J Affect Disord
(1990) - et al.
Cholesterol fractions, symptom burden, and suicide attempts in mood disorders
Psychiatry Res
(2012) Cultural variation in seasonal depression: cross-national differences in winter versus summer patterns of seasonal affective disorder
J Affect Disord
(2009)
Contrasts between symptoms of summer depression and winter depression
J Affect Disord
Anxiety disorders and anxiety symptoms in a clinic sample of seasonal and non-seasonal depressives
J Affect Disord
Seasonal changes in affective state measured prospectively and retrospectively
Br J Psychiatry
Epidemiological findings of seasonal changes in mood and behavior. A telephone survey of Montgomery County, Maryland
Arch Gen Psychiatry
Seasonal variation of depression and other moods: a longitudinal approach
J Biol Rhythms
A longitudinal investigation of seasonal variation in mood
Chronobiol Int
Do seasons have an influence on the incidence of depression? The use of an internet search engine query data as a proxy of human affect
PLoS One
Seasonality and affective illness
Am J Psychiatry
Seasonal affective disorder. A description of the syndrome and preliminary findings with light therapy
Arch Gen Psychiatry
Seasonal affective disorder
Am Fam Physician
An overview of epidemiological studies on seasonal affective disorder
Acta Psychiatr Scand
Epidemiology of recurrent major and minor depression with a seasonal pattern. The National Comorbidity Survey
Br J Psychiatry
Estimated prevalence of the seasonal subtype of major depression in a Canadian community sample
Can J Psychiatry
Seasonal mood disorders. Patterns of seasonal recurrence in mania and depression
Arch Gen Psychiatry
Cited by (20)
Delivery of bright light therapy within the Veterans Health Administration
2024, Journal of Affective DisordersNo evidence of seasonal variation in mild forms of depression
2019, Journal of Behavior Therapy and Experimental PsychiatryCitation Excerpt :A seasonal pattern of depression is less likely to be found in studies that: a) employ instruments that measure current symptoms and are consistent with DSM diagnostic criteria, b) determine seasonal pattern based on observed cases, rather than recall of past episodes, c) use population-representative samples, and d) collect data in a double-blind fashion. The number of studies that meet some or all of these criteria and that fail to demonstrate seasonal depression is growing (Blazer et al., 1998; Cobb et al., 2014; Hardt & Gerbershagen, 1999; Kerr et al., 2013; A.; Magnusson et al., 2000; Michalak et al., 2004; Nillni et al., 2009; Traffanstedt et al., 2016). Rosenthal has stated that SAD is, “not just a seasonal syndrome, it's a light deficiency syndrome” (Overy & Tansey, 2014).
Seasonality of depressive symptoms in women but not in men: A cross-sectional study in the UK Biobank cohort
2018, Journal of Affective DisordersCitation Excerpt :A number of studies have found no or very weak evidence for seasonal fluctuations in mood or rates of depression (Traffanstedt et al., 2016; Winthorst et al., 2014), and, of studies that do report seasonal variation, many employ subjective and poorly validated measures such as the Seasonal Pattern Assessment Questionnaire (Magnusson, 1996). In patients diagnosed with a seasonal form of major depressive disorder, only a small minority reliably and persistently show a seasonal pattern (Cobb et al., 2014). The majority of studies simply report cross-sectional differences in outcomes between summer and winter months, or quadratic curves across months (Patten et al., 2017).
Pupillary response abnormalities in depressive disorders
2016, Psychiatry ResearchCitation Excerpt :Some studies found higher prevalence of SAD at higher latitudes, suggesting at least some individuals are vulnerable to developing a disordered mood in response to the environmental stress of changing light (Imai et al., 2003; Kegel et al., 2009), but prospective studies show a lack of diagnostic stability for SAD (Leonhardt et al., 1994; Sakamoto et al., 1995; Schwartz et al., 1996; Thompson et al., 1995). In the longest follow-up study to date, seasonality was not stable from one decade to the next, yet a winter predominance for depression was confirmed (Cobb et al., 2014). The episodic and multifactorial nature of mood disorders renders such studies based on clinical features challenging.
Seasonality and symptoms of depression: A systematic review of the literature
2019, Epidemiology and Psychiatric Sciences