Estimating depression prevalence from the Beck Depression Inventory: is season of administration a moderator?

Seasonality and symptoms of depression: A systematic review of the literature

AIMS

Lay opinions and published papers alike suggest mood varies with the seasons, commonly framed as higher rates of depression mood in winter. Memory and confirmation bias may have influenced previous studies. We therefore systematically searched for and reviewed studies on the topic, but excluded study designs where explicit referrals to seasonality were included in questions, interviews or data collection.

METHODS

Systematic literature search in Cochrane database, DARE, Medline, Embase, PsychINFO and CINAHL, reporting according to the PRISMA framework, and study quality assessment using the Newcastle-Ottawa scale. Two authors independently assessed each study for inclusion and quality assessment. Due to large heterogeneity, we used a descriptive review of the studies.

RESULTS

Among the 41 included studies, there was great heterogeneity in regards to included symptoms and disorder definitions, operationalisation and measurement. We also observed important heterogeneity in how definitions of 'seasons' as well as study design, reporting and quality. This heterogeneity precluded meta-analysis and publication bias analysis. Thirteen of the studies suggested more depression in winter. The remaining studies suggested no seasonal pattern, seasonality outside winter, or inconclusive results.

CONCLUSIONS

The results of this review suggest that the research field of seasonal variations in mood disorders is fragmented, and important questions remain unanswered. There is some support for seasonal variation in clinical depression, but our results contest a general population shift towards lower mood and more sub-threshold symptoms at regular intervals throughout the year. We suggest future research on this issue should be aware of potential bias by design and take into account other biological and behavioural seasonal changes that may nullify or exacerbate any impact on mood.

No evidence of seasonal variation in mild forms of depression

BACKGROUND AND OBJECTIVES

Seasonal Affective Disorder (SAD) is ubiquitous in popular culture and has influenced psychiatric diagnosis with the inclusion of the seasonal pattern modifier for the Major Depressive Episode in DSM. However, recent research has not supported the association of Major Depressive Episode with seasonal changes. The present study was conducted to determine if a seasonally-related pattern of occurrence of mild variants of depression could be demonstrated in a population-based study.

METHODS

This is a cross-sectional U.S. survey of adults who completed the PHQ-8 Depression Scale with mild depression defined using a PHQ-8 cut score and a second model based on the DSM-5 diagnosis, Depression with insufficient symptoms. Regression models were used to determine if either variant of mild depression was related to season, latitude, or measures of daylight hours.

RESULTS

Neither measure of mild depression was related to daylight hours or its proxy measures.

LIMITATIONS

Screening instruments for depression, even if consistent with DSM-5 diagnostic criteria, do not allow a formal diagnosis of depression or the exclusion of similar-appearing disorders. Current depression symptoms but not duration of depressive episode is measured.

CONCLUSIONS

Mild depression is not related to seasonal changes or proxy measures of light exposure. The findings cast doubt on light deficiency as a causal factor of depressive disorders, which underpins the inclusion of the seasonal pattern modifier in DSM-5 and light supplementation as a treatment modality.

Seasonal variation in major depressive episode prevalence in Canada

BACKGROUND

The purpose of this paper is to describe variation, over the months of the year, in major depressive episode (MDE) prevalence. This is an important aspect of the epidemiological description of MDE, and one that has received surprisingly little attention in the literature. Evidence of seasonal variation in MDE prevalence has been weak and contradictory. Most studies have sought to estimate the prevalence of seasonal affective disorder using cut-points applied to scales assessing mood seasonality rather than MDE. This approach does not align with modern classification in which seasonal depression is a diagnostic subtype of major depression rather than a distinct category. Also, some studies may have lacked power to detect seasonal differences. We addressed these limitations by examining the month-specific occurrence of conventionally defined MDE and by pooling data from large epidemiological surveys to enhance precision in the analysis.

METHOD

Data from two national survey programmes (the National Population Health Survey and the Canadian Community Health Survey) were used, providing ten datasets collected between 1996 and 2013, together including over 500,000. These studies assessed MDE using a short form version of the Composite International Diagnostic Interview (CIDI) for major depression, with one exception being a 2012 survey that used a non-abbreviated version of the CIDI. The proportion of episodes occurring in each month was evaluated using items from the diagnostic modules and statistical methods addressing complex design features of these trials. Overall month-specific pooled estimates and associated confidence intervals were estimated using random effects meta-analysis and a gradient was assessed using a meta-regression model that included a quadratic term.

RESULTS

There was considerable sampling variability when the month-specific proportions were estimated from individual survey datasets. However, across the various datasets, there was sufficient homogeneity to justify the pooling of these estimated proportions, producing large gains in precision. Seasonal variation was clearly evident in the pooled data. The highest proportion of episodes occurred in December, January and February and the lowest proportions occurred in June, July and August. The proportion of respondents reporting MDE in January was 70% higher than August, suggesting an association with implications for health policy. The pattern persisted with stratification for age group, sex and latitude.

CONCLUSIONS

Seasonal effects in MDE may have been obscured by small sample sizes in prior studies. In Canada, MDE has clear seasonal variation, yet this is not addressed in the planning of services. These results suggest that availability of depression treatment should be higher in the winter than the summer months.

Seasonal variation in clinical remission of primary care patients with depression: impact of gender

RATIONALE, AIMS AND OBJECTIVES

The impact of seasonal variation on clinical remission in patients with depression has not been well studied. The hypothesis for this study was that the clinical remission rate would be lower in the winter comparing to the other seasons, specifically evaluated by gender.

METHODS

The study cohort comprised 2873 primary care patients with depression as a longitudinal retrospective chart review analysis. The sample was limited to patients who were continuing in care; dropouts were excluded from the analysis.

RESULTS

Multivariate logistic regression analysis of the independent variables for those participants who achieved clinical remission demonstrated that for the male patients, the season of diagnosis did not impact the rate of remission at 6 months while controlling for all other independent variables. For female patients, those that were diagnosed with depression in the fall had increased likelihood of 6-month remission compared with those patients diagnosed in the winter months (OR 1.300, CI 1.006-1.680, P=0.045) and the spring and summer patients were not significantly different in their outcome rates. When both genders were combined, the odds of remission at 6 months were not statistically significant for any season of diagnosis.

CONCLUSIONS

This study demonstrates that in patients who were continuing care, women who were diagnosed with major depression or dysthymia in the fall season have improved 6-month clinical outcome of remission compared with those women diagnosed in the winter, when controlling for demographic and clinical characteristics. This effect was not seen in men or when the genders were combined into a single cohort. The assessment of the seasonality effect on depression outcomes requires further long-term follow-up studies.

Self-attributed seasonality of mood and behavior: a report from the Netherlands study of depression and anxiety

BACKGROUND

Seasonal changes in mood and behavior are considered to be common in the general population and in patients with psychiatric disorders. However, in several studies this seasonality could not be demonstrated. The present study examined self-attributed seasonality of depressive symptoms among patients with a lifetime diagnosis of a depressive disorder (D), an anxiety disorder (A), a comorbid depressive and anxiety disorder (DA), and healthy controls (HC).

METHODS

The CIDI was used to establish diagnoses according to DSM-IV criteria in 2,168 participants of the Netherlands Study of Depression and Anxiety (NESDA). The Seasonal Pattern Assessment Questionnaire (SPAQ) was administered to assess variation in mood and behavior.

RESULTS

Of the 2,168 participants 53.5% reported seasonality of mood. Highest percentages of low mood were seen in the winter months. Although all groups showed this pattern of lowered mood during the winter months, D, A, and DA were significantly (P < .001) more likely to experience seasonality is this respect. This was also shown for seasonal changes in energy, social activities, sleeping, eating, weight and for the Global Seasonality Score. A limitation of this study was the cross-sectional design.

CONCLUSIONS

Seasonal variation in mood and behavior was demonstrated for both participants with a lifetime diagnosis of depression and/or anxiety disorder and for healthy controls, but patients with anxiety and/or depression were more likely to experience this seasonal variation. Clinicians should take into account that the time of the year could influence the feelings of well- and ill-being of their patients.

Two longterm studies of seasonal variation in depressive symptoms among community participants

BACKGROUND

There is evidence that seasonal variation in depressive symptoms is common in the population. However, research is limited by a reliance on longterm retrospective methods.

METHODS

Seasonal patterns were tested in two samples of community participants recruited in separate prospective studies in the Midwestern (n=556 males/females) and Pacific Northwestern (n=206 males) United States. Participants completed self-report measures of depressive symptoms 10-19 times from ages 14 to 36 years (n=8316 person observations). These data were compared with local meteorological conditions (e.g., solar radiation) recorded across the 2 weeks prior to each self-report.

RESULTS

In within-subjects analyses, participants' depressive symptoms and the probability of clinically significant symptoms varied with the time of year, as hypothesized (highest in the weeks of early Winter; lowest in early Fall). However, effect sizes were modest and were not explained by recent sunlight or other meteorological conditions.

LIMITATIONS

Samples were not nationally representative. Participants did not complete retrospective reports of seasonal depression or measures of current vegetative symptoms.

CONCLUSIONS

Neither time of the year nor recent seasonally linked meteorological conditions were powerful influences on depressive symptoms experienced by community populations in relevant geographic regions. Prior studies may have overestimated the prevalence and significance of seasonal variation in depressive symptoms for the general population.

Seasonality in depressive and anxiety symptoms among primary care patients and in patients with depressive and anxiety disorders; results from the Netherlands Study of Depression and Anxiety

BACKGROUND

Little is known about seasonality of specific depressive symptoms and anxiety symptoms in different patient populations. This study aims to assess seasonal variation of depressive and anxiety symptoms in a primary care population and across participants who were classified in diagnostic groups 1) healthy controls 2) patients with a major depressive disorder, 3) patients with any anxiety disorder and 4) patients with a major depression and any anxiety disorder.

METHODS

Data were used from the Netherlands Study of Depression and Anxiety (NESDA). First, in 5549 patients from the NESDA primary care recruitment population the Kessler-10 screening questionnaire was used and data were analyzed across season in a multilevel linear model. Second, in 1090 subjects classified into four groups according to psychiatric status according to the Composite International Diagnostic Interview, overall depressive symptoms and atypical versus melancholic features were assessed with the Inventory of Depressive Symptoms. Anxiety and fear were assessed with the Beck Anxiety Inventory and the Fear questionnaire. Symptom levels across season were analyzed in a linear regression model.

RESULTS

In the primary care population the severity of depressive and anxiety symptoms did not show a seasonal pattern. In the diagnostic groups healthy controls and patients with any anxiety disorder, but not patients with a major depressive disorder, showed a small rise in depressive symptoms in winter. Atypical and melancholic symptoms were both elevated in winter. No seasonal pattern for anxiety symptoms was found. There was a small gender related seasonal effect for fear symptoms.

CONCLUSIONS

Seasonal differences in severity or type of depressive and anxiety symptoms, as measured with a general screening instrument and symptom questionnaires, were absent or small in effect size in a primary care population and in patient populations with a major depressive disorder and anxiety disorders.

Fatigue: a principal contributor to impaired quality of life in ANCA-associated vasculitis

OBJECTIVES

To describe quality of life (QoL) in an ANCA-associated vasculitis (AAV) cohort and make comparisons with a general population sample. In addition, we aimed to take preliminary steps to identify potential disease and psycho-social factors which may determine QoL impairment.

METHODS

A population-based case-control study was designed. All AAV patients resident in Grampian, Scotland, were invited to participate as cases. Controls were identified from a random sample of persons registered with four local general practices. Participants completed a questionnaire comprising validated generic and symptom-specific tools in the assessment of QoL. In addition, all cases were clinically assessed and putative disease factors recorded. Cases and controls were compared and, in addition, disease and psycho-social associations were explored for identified QoL impairments.

RESULTS

In total, 74/90 (82%) cases and 781/2000 (39%) controls participated. Cases reported a significant impairment in physical health (P < 0.0001), but not mental health (P = 0.85), compared with controls, as measured by Short Form-8 (SF-8). Following adjustment for age and sex, persons with AAV were more than twice as likely to report mild/moderate fatigue [odds ratio (OR) 2.0; 95% CI 1.1, 3.8] or severe fatigue (OR 2.5; 95% CI 1.4, 4.5) compared with controls. Furthermore, among cases, fatigue was found to be strongly associated with impaired physical health (P < 0.0001), while disease factors such as disease activity and damage were not (P = 0.60 and 0.27, respectively).

CONCLUSIONS

Patients with AAV report impaired physical but not mental health. Specifically, fatigue is a principal complaint and appears to be a major determinant of impaired QoL.

Mechanisms of behavior change in alcoholics anonymous: does Alcoholics Anonymous lead to better alcohol use outcomes by reducing depression symptoms?

RATIONALE

Indices of negative affect, such as depression, have been implicated in stress-induced pathways to alcohol relapse. Empirically supported continuing care resources, such as Alcoholics Anonymous (AA), emphasize reducing negative affect to reduce relapse risk, but little research has been conducted to examine putative affective mechanisms of AA's effects.

METHODS

Using lagged, controlled, hierarchical linear modeling and mediational analyses this study investigated whether AA participation mobilized changes in depression symptoms and whether such changes explained subsequent reductions in alcohol use. Alcohol-dependent adults (n = 1706), receiving treatment as part of a clinical trial, were assessed at intake, 3, 6, 9, 12 and 15 months.

RESULTS

Findings revealed elevated levels of depression compared to the general population, which decreased during treatment and then remained stable over follow-up. Greater AA attendance was associated with better subsequent alcohol use outcomes and decreased depression. Greater depression was associated with heavier and more frequent drinking. Lagged mediation analyses revealed that the effects of AA on alcohol use was mediated partially by reductions in depression symptoms. However, this salutary effect on depression itself appeared to be explained by AA's proximal effect on reducing concurrent drinking.

CONCLUSIONS

AA attendance was associated both concurrently and predictively with improved alcohol outcomes. Although AA attendance was associated additionally with subsequent improvements in depression, it did not predict such improvements over and above concurrent alcohol use. AA appears to lead both to improvements in alcohol use and psychological and emotional wellbeing which, in turn, may reinforce further abstinence and recovery-related change.

Seasonal trends in depressive problems among United States children and adolescents: a representative population survey

This study examined season-of-assessment differences in parent and child reports of depressive problems on well-validated instruments in 2009 U.S. children and adolescents, aged 6 to 18 years, from a nationally representative population survey. A parent completed the Child Behavior Checklist (CBCL) for each participant and 1226 of the 11-18-year-olds completed the Youth Self-Report (YSR). Outcome measures were CBCL and YSR withdrawn/depressed syndrome scale scores and rates of clinically elevated scores. Overall fall/winter versus spring/summer differences were not found on the CBCL or YSR for depressive problem severity or rates of depressive problems. Age, sex, and latitude were examined as potential moderators of the association between season-of-assessment and the outcomes. Of these, the effect of season-of-assessment on CBCL depressive problem severity depended upon age. Parents of 16-18-year-old adolescents rated depressive problems as significantly more severe in fall and winter than in spring and summer. Parents also rated depressive problems as significantly more severe in 16-18-year-olds than in 6-15-year-olds, but only when assessed in the fall and winter. There were no season-of-assessment differences among 6-15-year-old children and adolescents. The overall lack of season-of-assessment differences and the finding of age as a moderator on only one of four outcomes suggest minimal seasonality effects.

Omnibus hypothesis testing in dominance-based ordinal multiple regression

Often quantitative data in the social sciences have only ordinal justification. Problems of interpretation can arise when least squares multiple regression (LSMR) is used with ordinal data. Two ordinal alternatives are discussed, dominance-based ordinal multiple regression (DOMR) and proportional odds multiple regression. The Q2 statistic is introduced for testing the omnibus null hypothesis in DOMR. A simulation study is discussed that examines the actual Type I error rate and power of Q2 in comparison to the LSMR omnibus F test under normality and non-normality. Results suggest that Q2 has favorable sampling properties as long as the sample size-to-predictors ratio is not too small, and Q2 can be a good alternative to the omnibus F test when the response variable is non-normal.