Extreme Heat May Hasten Cognitive Decline 

July 2023 was the hottest month on record, with cities like Phoenix experiencing record-breaking heat waves for weeks on end. 

A new study finds that ongoing extreme heat can worsen cognitive decline among vulnerable groups — particularly Black older adults and those living in poor neighborhoods.

Extreme heat is the leading cause of weather-related deaths in the U.S., claiming more lives each year than hurricanes, tornadoes, and lightning combined. Young children and older adults are particularly vulnerable to heat-related illnesses such as heat exhaustion and heat stroke.

Recent studies suggest that high temperatures may hurt cognitive function, but these studies tend to look at a snapshot of someone’s cognition at a single time point following brief exposure to heat. Less is known about the long-term consequences of heat on cognitive health.

As heat waves become more frequent and intense due to climate change and urban heat islands, the researchers sought to understand the connection between extreme heat exposure and cognitive decline. They analyzed data from nearly 9,500 U.S. adults ages 52 and older surveyed over a 12-year period (2006-2018) as part of the Health and Retirement Study conducted by the University of Michigan Institute for Social Research, which measures participants’ cognitive function over time.

The researchers also looked at socioeconomic measures of the neighborhoods where participants lived. In addition, they calculated participants’ cumulative exposure to extreme heat (the number of days in which the heat index reached or exceeded a location-specific threshold) during this 12-year period based on historical temperature data from the CDC’s National Environmental Public Health Tracking Network.

They found that high exposure to extreme heat was associated with faster cognitive decline among residents of poor neighborhoods, but not for those in wealthier neighborhoods.

Moreover, cumulative exposure to extreme heat was associated with faster cognitive decline among Black older adults, but not white or Hispanic older adults. (The study did not have enough participants of other races and ethnicities to include them in the analysis.)

The researchers urge local governments and health officials to develop policies and tools that identify residents who are susceptible to extreme heat, empower at-risk communities, map their specific needs, and develop targeted support and increased communication with these populations.

Sources:

Eun Young Choi, Haena Lee, Virginia W Chang. Cumulative exposure to extreme heat and trajectories of cognitive decline among older adults in the USA. Journal of Epidemiology and Community Health, 2023; jech-2023-220675 DOI: 10.1136/jech-2023-220675

New York University. (2023, August 15). Extreme heat may hasten cognitive decline in vulnerable populations. ScienceDaily. Retrieved August 16, 2023 from www.sciencedaily.com/releases/2023/08/230815151126.htm

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