Winter Blues in Zurich – Just How Common Is Seasonal Depression?
What do we know about those “winter blues” we feel during those colder months, in which the medical community defines as Seasonal Affective Disorder? It has often been a point of interest within pop culture and medicine, especially through its integration into medical terminology in 1986, but just how exactly does it manifest within human psyche and behaviour? That is one of many questions researchers of the Zurich longitudinal cohort study wanted to answer as they sought to better understand seasonal depression and the psychological impacts it has on individuals. The longitudinal cohort study draws from five semi-structured interviews conducted within the homes of inhabitants within the Swedish community of Zurich from 1986 to 2008. 591 subjects, ages ranging from 20-50 years, were selected after being screened for mental health diagnoses. Approximately 66% were labeled as being “high risk” individuals with a mental diagnosis and the other 33% were labeled as “low-risk”. Other mental health diagnoses of subjects, such as addiction, bipolar disorder, and/or personal trauma, were also taken into consideration by researchers
What are the facts on SAD? For context, Season Affective Disorder (SAD), also known as seasonality, refers to the depressive disorder felt specifically during the autumnal and winter months of the year. Symptoms typically diminishing with the arrival of the warmer seasons. The prevalence range of SAD in North America, alone, is estimated to be 1.4 – 9.7%, whereas in Europe and Asia, it is 1.3 to 3.0% and 0 to 0.9%. SAD is generally rare in Nordic regions with insignificant seasonal changes, such as Finland and Iceland, most likely due to behavioural and genetic adaptation exhibited by native populations. For the Zurich study, the authors were particularly interested in how seasonality differed between individuals who experienced numerous unipolar and bipolar depressive episodes during colder seasons versus those who experienced those who experienced one depressive episode. At-home interviews were conducted every few years with interviewers first inquiring about the overall mental state of their subjects during the autumnal and winter months, such questions asked were whether they felt tired, dejected, depressed, and/or just plain “blue” as a result of the seasonal change. Depressive symptoms and seasonality would then be evaluated in subsequent interviews.
Overall, findings indicate that those who experienced one depressive episode comprised 9.96% versus the 3.4% who experienced multiple episodes brought as a result of temperatures dropping. Women were also five times more likely to be affected by SAD. Furthermore, symptoms of depression and anxiety and/or agoraphobia were more likely to be exhibited by participants, especially members who experienced multiple episodes of depression, thereby highlighting the comorbidity present within SAD. Participants also reported an increase in overall fatigue, as well as increases in appetite and weight gain. Additionally, subjects also reported waking up depressed, along with experiencing overall hypersensitivity to light, noise, and smell. According to the report, 7.52% of subjects experienced this illness during the study.
To conclude, the authors acknowledge that their research design is flawed in regards to its 8 year hiatus from 1999-2007 in which no interviews were conducted. Nonetheless, this study suggests that SAD is a serious mental health issue and should be regarded as such. As more studies are proving the effects of SAD, it is vital that there be more focus on combating symptoms, one such technique being light-therapy. At the end of the day, those “winter blues” are something we all undergo, one of many reasons to further investigate this.
Source:
Wirz-Justice, A., Ajdacic, V., Rössler, W., Steinhausen, H. C., & Angst, J. (2018). Prevalence of seasonal depression in a prospective cohort study. European archives of psychiatry and clinical neuroscience, 1-7.
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