Extreme heat and cold threaten health of people with dementia

Exposure to extreme heat and cold is associated with an increased risk of emergency department (ED) visits among people living with dementia, according to preliminary research presented today at the European Academy of Neurology (EAN) Congress 2026. The findings provide new evidence that environmental factors can have measurable effects on the health of people with neurological disorders.

As climate change increases the frequency and intensity of extreme weather events, understanding how environmental conditions affect people with neurological disorders is becoming an increasingly important public health priority. However, relatively little is known about how temperature extremes influence the short-term health of people living with dementia and Parkinson's disease.

Researchers from the IRCCS Institute of Neurological Sciences of Bologna, Italy, analyzed ED visits recorded between 2015 and 2024 among 13,680 people with dementia and 2,755 people with Parkinson's disease living in the municipality of Bologna to determine whether exposure to extreme temperatures was associated with an increased risk of ED attendance.

The analysis found that exposure to both extreme heat and extreme cold was associated with increased ED visits among people with dementia. Exposure to extreme heat (approximately 29.7°C, corresponding to the 95th percentile of observed temperatures) was associated with an 11% increase in ED visits within the first three days following exposure (RR=1.11; 95% CI 1.04–1.19).

Exposure to extreme cold (approximately 1.5°C, corresponding to the 5th percentile of observed temperatures) was associated with a delayed increase in risk, reaching 14% around 10 days after exposure (RR=1.14; 95% CI 1.03–1.26).

The strongest heat-related effect was observed among people aged 70–90 years, whose risk of ED attendance increased by 19% within the three days after the exposure (RR=1.19; 95% CI 1.10-1.29).

In contrast, the preliminary analysis found no clear evidence that extreme temperatures increased ED visits among people with Parkinson's disease. Researchers observed a possible trend following exposure to extreme heat that warrants further investigation, but no clear association with cold temperatures.

They caution that the smaller Parkinson's disease cohort may have limited the statistical power of the analysis and that different temperature thresholds may be relevant for this population.

The researchers also observed a phenomenon known as a "harvesting effect", whereby periods of increased ED attendance were followed by a temporary reduction in risk. This suggests that extreme temperatures may accelerate health events that would otherwise have occurred later.

In both hot and cold conditions, we observed evidence that extreme temperatures may accelerate health events that would otherwise have occurred later. This concentration of healthcare demand may have organizational implications for health services."

Dr. Luca Vignatelli, lead author

He added: "The difference in risk trends following exposure to extreme temperatures between dementia and Parkinson's disease is only partly surprising, as it underscores the fact that these two conditions are underpinned by two distinct disease processes, even though they are broadly grouped together under the umbrella of neurodegenerative diseases."

The researchers believe several biological and behavioural mechanisms may explain why people with dementia appear particularly vulnerable to extreme temperatures.

"In degenerative diseases, we can hypothesise two mechanisms of deterioration linked to exposure to extreme temperatures," Dr Vignatelli explained. "The first is an indirect effect, whereby physiological stress is induced in a frail body. The second, which is less obvious and still needs to be proven, is that extreme temperatures may accelerate neurodegenerative pathogenic mechanisms."

Behavioural factors may also play an important role. "It is possible that a person with dementia may fail to adopt protective behaviours because cognitive impairment reduces their perception of risk," Dr Vignatelli said. "In individuals with Parkinson's disease, this may be less evident, as cognitive impairment is less common and generally occurs later in the course of the disease."

The findings may have implications not only for patients and carers but also for healthcare systems planning for periods of extreme weather.

The researchers say the findings highlight the need for measures to better protect vulnerable populations during periods of extreme weather.

"For both hot and cold periods, local health authorities should promote social and urban planning solutions aimed at reducing social isolation and establishing easily accessible climate shelters," Dr Vignatelli noted. "During hot weather, healthcare professionals should take proactive measures to support people with cognitive impairment, while telemedicine could be a useful tool for providing flexible clinical care during both hot and cold weather."

The findings form part of the wider MANDEA project, which is investigating how climate, air pollution, green spaces and socioeconomic factors influence the health of people living with neurological disorders. The researchers hope the project will provide evidence to help healthcare systems better prepare for the growing health impacts of climate change.