The influence of weather on the course of bipolar disorder: A systematic review

Background and objectives: Several studies have addressed the relationship between bipolar disorder and meteorological variables, but no previous review focusing on the influence of a wide range of meteorological variables on bipolar disorder has been published. The aim of this study is to conduct a systematic review about the influence of weather on the clinical course of bipolar disorder patients. Methods: Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the main electronic medical databases were searched in February 2020, and studies were screened based on the eligibility criteria. 24 studies were selected for qualitative synthesis. Most of them were observational retrospective studies based in medical records. Results: The most studied meteorological variables were temperature and sunlight, and the most studied clinical outcomes were hospital admissions. Significant correlations were found between temperature and sunlight and clinical outcomes, although the findings were heterogeneous. Higher temperatures may trigger bipolar disorder relapses that require hospital admission, and higher expositions to sunlight may increase the risk of manic episodes. Conclusion: Meteorological variables seem to have an influence in the course of bipolar disorder, especially temperature and sunlight, although further studies are needed to clarify this possible relationship. (C) 2021 Asociacion Universitaria de Zaragoza para el Progreso de la Psiquiatria y la Salud Mental. Published by Elsevier Espana, S.L.U. AU rights reserved.