So, I have to admit I get a bit amused when so many news articles start getting published about a single study; particularly when they make broad conclusions like “Seasonal Affective Disorder is a myth.” Sometimes it is hard to blame science writers and other reporters when the abstract of a study includes lines like “The idea of seasonal depression may be strongly rooted in folk psychology, but it is not supported by objective data.”
I find it amusing that one study that was published online in January appears to have gotten a lot of attention in the media, but another study with conflicting recommendations that was also published online in January hasn’t.
Let’s get ready to Rumble!
Published “online first” in Clinical Psychological Science January 19, 2016:
- Steven G. LoBello, Department of Psychology, Auburn University at Montgomery, PO Box 244023, Montgomery, AL 36117 E-mail: firstname.lastname@example.org
Author Contributions M. K. Traffanstedt and S. G. LoBello developed and S. Mehta contributed to the study concept and design. M. K. Traffanstedt gathered data from the USNO and performed the data analysis with S. G. LoBello. Programming entailed the combining of BRFSS with USNO data and this was done by S. G. LoBello and M. K. Traffanstedt. M. K. Traffanstedt interpreted the results under the supervision of S. G. LoBello and S. Mehta. M. K. Traffanstedt drafted the manuscript, and S. G. LoBello and S. Mehta provided critical revisions. All authors approved the final version of the manuscript for submission.
Seasonal affective disorder (SAD) is based on the theory that some depressions occur seasonally in response to reduced sunlight. SAD has attracted cultural and research attention for more than 30 years and influenced the DSM through inclusion of the seasonal variation modifier for the major depression diagnosis. This study was designed to determine if a seasonally related pattern of occurrence of major depression could be demonstrated in a population-based study. A cross-sectional U.S. survey of adults completed the Patient Health Questionnaire–8 Depression Scale. Regression models were used to determine if depression was related to measures of sunlight exposure. Depression was unrelated to latitude, season, or sunlight. Results do not support the validity of a seasonal modifier in major depression. The idea of seasonal depression may be strongly rooted in folk psychology, but it is not supported by objective data. Consideration should be given to discontinuing seasonal variation as a diagnostic modifier of major depression.
And now, in this corner… the throwdown opponent!!!
Published online 11 January 2016
S. B. Pattena1a2a3 c1, J. V. A. Williamsa1, D. H. Lavoratoa1, A. G. M. Bullocha1a2a3, K. M. Fiesta4, J. L. Wanga1a2a3 and T. T. Sajobia5
a1 Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada
a2 Department of Psychiatry, University of Calgary, Calgary, Alberta, Canada
a3 Mathison Centre for Mental Health Research & Education, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
a4 Department of Internal Medicine (Neurology), University of Manitoba, Winnipeg, Manitoba, Canada
a5 Department of Community Health Sciences and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, 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.
(Received August 25 2015)
(Accepted December 12 2015)
- Epidemiologic studies;
- major depressive episode;
- seasonal affective disorder;
- winter depression
c1 Address for correspondence: S. B. Patten, Department Community Health Sciences, 3rd Floor TRW Building, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, AB T2N 4Z6, Canada. (Email: email@example.com)