People living with Alzheimer’s disease, related dementias vulnerable to extreme heat

Extreme heat is a health hazard to older people living with Alzheimer's disease and dementia (ADRD), having been associated with increased hospitalizations in a recent study.

In a large cohort of 3,329,977 Medicare beneficiaries (mean age 82.52 years, 63.9 percent female, 85.0 percent White), exposure to high heat index was associated with significant increases in the odds of hospitalization with ADRD (99th vs 50th percentile of the heat index distribution: odds ratio [OR], 1.02, 95 percent confidence interval [CI], 1.01–1.02), translating to 0.8 additional hospitalizations with ADRD per 1,000 beneficiaries. [JAMA Intern Med 2025;doi:10.1001/jamainternmed.2024.7719]

Extreme heat had a lingering effect, persisting for 3 days after just a single day of exposure, as pointed out by the investigators. “Thus, even when heat indexes return to the median after a day of extreme heat, the increased hospitalization risk may persist.”

Accordingly, the effects of extreme heat intensified with consecutive days of exposure, they added. The odds for hospitalization with ADRD went up from 2 percent after a single day to 4 percent after 4 days of continuous exposure to heat indexes at the 99th vs the 50th percentile (OR, 1.04, 95 percent CI, 1.03–1.04). This corresponded to 1.7 (95 percent CI, 1.3–2.0) additional hospitalizations with ADRD per 1,000 beneficiaries.

The effects of extreme heat exposure did not significantly differ between temperate and continental climates. However, the effects of 4 days of continuous extreme heat exposure were 2.6 to 3.2 times larger for beneficiaries identifying as Asian (OR, 1.09, 95 percent CI, 1.02–1.17), Black (OR, 1.07, 95 percent CI, 1.05–1.10), and Hispanic (OR, 1.08, 95 percent CI, 1.03-1.13) than for White beneficiaries (OR, 1.03, 95 percent CI, 1.02–1.04).

“Extrapolating these estimates to the 6.7 million adults currently living with ADRD suggests that each day of extreme heat could contribute to at least 5,360 added hospitalizations with ADRD nationwide,” the investigators said.

They emphasized that patients living with ADRD face unique challenges compared with their cognitively intact peers. As such, clinicians may consider several strategies to manage increased risk from extreme heat.

“At the patient level, educating patients and caregivers on the risk of extreme heat given ADRD-related thermoregulatory deficits is important, particularly when patients require psychotropic medications. Clinicians may also work with social service providers to ensure patients have adequate social support and access to air-conditioned spaces,” the investigators said.

“At the policy level, clinicians may advocate for systemic solutions, ranging from community programs supporting adults living with ADRD to policies to adapt to and mitigate climate change. Targeted programs, including those focused on Asian, Black, and Hispanic beneficiaries, may yield the largest population health gains while reducing racial and ethnic health inequities,” they added.