Story at a glance
- The study was carried out in Bangladesh and researchers say results should serve as a warning for other nations.
- Exposure to worsening flooding was also associated with a greater risk of co-occurring depression and anxiety, and each individual condition.
- Additional associations were seen between rising humidity and co-occurring depression and anxiety.
Climate-related events like extreme heat and humidity take a toll on individuals’ mental health, according to a new study published Monday.
The study assessed the burden of depression and anxiety in populations experiencing climate-related shocks and stressors in Bangladesh.
The South Asian country is considered the world’s seventh most vulnerable to climate change and frequently experiences both extreme flooding and cyclones.
“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,” said study author Syed Shabab Wahid, an assistant professor in the department of global health at 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, globally,” Wahid said in a statement.
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In Bangladesh, the overall prevalence of depression is 16.3 percent, compared with the global rate of around 4.4 percent. Anxiety rates are also higher in the country compared with the rest of the world, at 6 percent vs. 3.6 percent.
Investigators carried out surveys in urban and rural areas to assess adults’ mental health. The surveys were conducted between Aug. and Sept., 2019, and Jan. and Feb., 2020. Researchers also measured climate-related variables at 43 weather stations throughout the country in the two-month period preceding each survey. A total of 3,606 individuals were included in the study.
Results showed individuals who experienced a one degree Celsius temperature rise during the two months had a 21 percent higher probability of an anxiety disorder and 24 percent higher likelihood of co-occurring depression and anxiety disorder.
Higher temperatures may affect the brain’s neurotransmitter environment, which could impact mood and cognitive function, authors explained. Increased temperatures have also been linked with irritability and psychological distress.
Researchers note the findings are especially concerning for populations who are exposed to the heat and sun thanks to daily labor or activities.
In addition, an increase in humidity (one gram of moisture per cubic meter of air) was linked with a six percent higher risk of co-occurring anxiety and depression.
Individuals were also asked if they were exposed to flooding within the twelve months before the surveys. Exposure to worsening flooding from climate change increased the risk of depression by 31 percent, anxiety by 69 percent, and both conditions by 87 percent. This finding suggests coastal populations are also highly vulnerable to mental health problems, authors added.
Overall, women, older populations and those with physical disabilities were particularly vulnerable to the mental health impacts of climate change.
“This study adds to growing literature from low-income, middle-income, and high-income countries that has identified climate-related stressors, such as elevated temperature and humidity and extreme weather shocks, to be significantly associated with adverse mental health outcomes,” study authors wrote.
By 2050, temperatures in Bangladesh are expected to increase by 1.4 degrees Celsius.
Going forward, researchers hope to develop and evaluate community-based interventions to help improve mental health in affected regions.
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