Extreme heat and humidity and other climate-related events appear to increase mental health disorders such as depression and anxiety, according to analysis focused on communities in Bangladesh.
While it is known that climate change can have serious repercussions for mental health, researchers say country-level data is lacking.
The study published February in Lancet Planetary Health relied on data that examined climate-related and sociodemographic links in Bangladesh, one of the world's most climate-vulnerable countries.
We have now established a high-water mark that, alas, could soon be eclipsed for how climate can impact mental health in a highly vulnerable country. This should serve as a warning for other nations."
Syed Shabab Wahid, lead author, assistant professor, Department of Global Health, Georgetown University's School of Health
"As climate change worsens, temperatures and humidity will continue to increase, as will natural disasters, such as extreme flooding, which portends worsening impact on our collective mental health," Wahid says.
Bangladesh faces multiple climate-related risks including elevated temperatures and humidity, heatwaves and natural disasters such as extreme flooding and cyclones. According to Wahid, this makes it a "suitable setting to examine several facets of the climate emergency".
The researchers measured climate-related variables at 43 weather stations in Bangladesh for changes in seasonal temperatures and humidity over a two-month period. They noted instances of exposure to flooding from study respondents which gave an indication of how small changes in weather events linked to climate can impact mental health outcomes.
Additionally, the researchers conducted two sets of surveys, in both urban and rural households, between August and September 2019 and January and February 2020, to assess depression and anxiety in adults.
People experiencing one-degree Celsius higher temperatures during the two months preceding the study had a 21 per cent higher probability of an anxiety disorder and a 24 per cent higher likelihood of both depression and an anxiety disorder simultaneously.
Exposure to worsening flooding linked to climate change in the region was attributed to increased odds of all conditions: depression by 31 per cent, anxiety by 69 per cent, and the presence of both conditions by 87 per cent.
Wahid says that the findings establish for the first time at a national level in Bangladesh, and in South Asia overall, the connection between elevated temperature, humidity or exposure to severe flooding, and adverse mental health outcomes in terms of depression and anxiety.
He says the researchers found increased vulnerability among all older age groups to depression and anxiety. "The older you are, the higher your likelihood of having one of these conditions. We also found higher vulnerability to depression for females."
Lise Van Susteren, co-founder of the Climate Psychiatry Alliance, says that data from this study is consistent with other studies and should be disseminated widely. "Extreme weather events, including higher temperatures, increased rainfall and certainly flooding, carry an alarming, attendant emotional toll."
The physical impacts of climate disruption can be more easily seen so they garner more attention, Van Susteren says, adding: "Psychological burdens, by contrast, often lie hidden, seeping unconsciously into and insinuating themselves into every aspect of our lives, and that of our families and communities. Grossly underreported, they are exceedingly difficult to treat."
Van Susteren believes there is a strong need for a subspecialty in climate and mental health, to educate the public and advocate for "bold policies that reduce the dangers to our mental and physical health".
"The study prompts those of us who are steeped in the world of climate distress to appreciate greatly studies that address this dangerous challenge to our health and future — because as bad as the storms are outside, the storms inside, especially in the long term, could be even worse," she adds.
Wahid, S.S., et al. (2023) Climate-related shocks and other stressors associated with depression and anxiety in Bangladesh: a nationally representative panel study. The Lancet Planetary Health. doi.org/10.1016/S2542-5196(22)00315-1.