An Umbrella Systematic Review of Seasonality in Mood Disorders and Suicide Risk: The Impact on Demand for Primary Behavioral Health Care and Acute Psychiatric Services

Objective: To review the current literature focusing on the most recent systematic reviews relating to mood, suicide, and psychiatric service utilization. 

Study Selection and Data Extraction: A systematic literature search of PubMed, CINAHL, and PsycINFO databases using the search terms "Systematic review" AND "season*" AND mood OR depression OR bipolar OR psychosis OR suicid* OR psychiatr* initially yielded 209 results. After screening by title and abstract for relevance, 6 records remained, while a further 3 were identified after screening of reference lists. A qualitative synthesis of these results was then performed due to data heterogeneity between studies. 

Results: We found evidence of winter peaks for depressive symptoms and suggestions of summer peaks for suicidal activity, emergency department (ED) self-harm presentations, and manic-related hospital admissions. Suicide is 11%-23% more frequent in spring and summer. ED suicide attempts are also 1.2-1.7 times higher in spring and summer compared to winter. Admissions for mania are 7.4%-16% higher in spring and summer, while there are 1.5 times more admissions for bipolar depression in winter months. 

Conclusions: There is a summer peak for many aspects of mental health activity, particularly in terms of acute hospital utilization and suicidality. This is contrary to the winter-related peak of depressive symptoms. Further research is needed to affirm these findings.