Dementia linked to greater heat vulnerability in Brazil
The association between heat and death was stronger in records mentioning dementia than those without it, with a comparison ratio of 1.044.
Case-control study, dose-response
Limit: Deaths with and without dementia differ in cause composition; an alternative comparison strengthened the association
Edited by Boris Djordjevic · AgingResearch.News
An observational study examined 3,672,003 deaths in 12 Brazilian states during January–May of 2014–2025. Researchers used a case-crossover design, comparing different days for the same individual. They defined hot days using the highest tenth of daily maximum temperatures within each month. They examined associations on the hot day and up to three days later, identifying health conditions from death certificates.
Dementia showed the strongest evidence of greater heat susceptibility among ten conditions tested. Obesity and diabetes showed little or no evidence of greater susceptibility. Separately, drowning had the largest heat-associated relative risk among external causes of death, at 1.161, where 1 would mean no association. Its association peaked on the hot day itself. Alzheimer’s disease had the highest relative risk among the specific natural causes examined, at 1.093.
Why it matters
Dementia is an age-related disease, making heat vulnerability relevant to care in later life. The authors suggested that behavior may contribute to heat vulnerability alongside the physical mechanisms usually considered.
Caveats
This observational analysis cannot establish cause and effect, and it identified health conditions from death certificates. The findings cover 12 Brazilian states during January–May and come from a preprint that has not been peer-reviewed.
The paper
My Brazilian Doctor
Research Square, Oct 22, 2026, Open access, Preprint, not peer-reviewed
