Weather and extreme heat in association to mental disorders The case of Hanoi, Vietnam

Sammanfattning: Background: Vietnam suffers consequences of global warming. There is limited data of therelationship between weather, extreme heat and potential mental health problems. It is thereforecrucial to study heat-related mental illnesses and to establish good solutions with relevantadaptations to global warming. The adaptation measures should give attention to people that live inareas facing annual extreme weather, and protecting health in general and more specifically mentalhealth of citizens. The study aimed to examine relationships between weather patterns, extremeheat or heatwaves, and mental disorders, and to investigate factors contributing to increasedvulnerability and susceptibility.Methods: The thesis includes a systematic review and a hospital-based study using data from theHanoi Mental Hospital for five years (2008 – 2012), with mental disorders diagnosed by ICD10(F00-99) to estimate the effects of weather variation, seasonality, increased temperatures, andheatwaves on hospital admissions for depression and other mental disorders. A negative binomialregression model accounting for yearly study period, time trends, and day of the week was used toanalyze the relationship between seasonality, heatwaves, and monthly and daily mental disorderhospitalizations.Results: Our findings showed (i) a general tendency for more admissions between May andDecember, with a seasonal bi-annual high between May-June and November-December, andelevated ambient temperature was significantly related to increasing admissions for depressivedisorders; (ii) the number of hospital cases for mental disorders increased in the summer seasonespecially in June, and two percent of cases emerged during elevated temperature of one degreeCelsius; and (iii) when compared with non-heatwave periods, heatwaves amounted to increasingrisks for admission for the whole group of mental disorders (F00-79), and admissions for mentaldisorders among residents in rural communities and in the elderly population increasedsignificantly during heatwaves.Conclusion: There were associations between hospital admissions for depression and othermental disorders and seasonality, weather patterns, elevated temperatures, and heatwaves. Theassociations grew stronger with the length of the heatwaves and particularly the elderly appearedmore sensitive to seasonality, hot weather and heatwaves.