Environmental heat exposure and cognitive performance in older adults: a controlled trial

Abstract

Thermal stress has a negative effect on the cognitive performance of military personnel and industry workers exposed to extreme environments. However, no studies have investigated the effects of environmental thermal stress on the cognitive functions of older adults. We carried out a controlled trial with 68 healthy older adults (mean age 73.3 years, 69 % female), each of whom has been assessed twice on the same day with selected tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Repeated sessions were conducted with air temperatures set at 24 °C and 32 °C in a balanced order. Our primary analyses did not show significant differences when comparing the cognitive performance of the total sample under the two experimental temperatures. However, interaction analysis has shown that humidity levels modify the effect of temperature on cognitive outcomes. The subgroup exposed to relative humidity greater than the median value (57.8 %) presented worse cognitive performance in the heat session when compared to the control session. Reported exercising frequency explained individual vulnerability to heat stress. Volunteers with lower levels of physical activity (<4 times per week) were more likely to present worsened cognitive performance under heat stress. In a fully adjusted linear regression model, the performance under heat stress remained associated with relative humidity (β = -0.21; p = 0.007) and frequency of exercising (β = 0.18; p = 0.020). Our results indicate that heat stress may have detrimental effects on the cognitive functioning of some subgroups of older adults and under particular circumstances. Further research is needed for exploring a variety of potentially influential factors.

Changes in EEG signals during the cognitive activity at varying air temperature and relative humidity

“…We are not able to provide the answer to why RH affects performance. However, the results are consistent with the work of Trezza et al [69] who showed that exposure to relative humidity higher than 57.8% reduces cognitive performance.…”

Modelos Bioclimáticos De Verão E Inverno Para Cidade Média Em Clima Subtropical

“…O crescimento do envelhecimento populacional, principalmente em cidade de médio e pequeno porte (Hoof and Hensen, 2006;Iommi and Barbera, 2015;Lai et al, 2014;Larose et al, 2014;Organização Mundial da Saúde, 2015;Schellen et al, 2010;Trezza et al, 2015), bem como o aumento da porcentagem de pessoas obesas em todo o planeta (Okada and Kakehashi, 2014;Vanos et al, 2012;WHO, 2017), fazem parte de um padrão crescente do novo modelo de crescimento populacional urbano.…”

Particulate matter inside residences of elderly in the Metropolitan Area of São Paulo

“…The thermal stress can cause health effects on the population of São Paulo, such as respiratory morbidity (Gonçalves et al, 2005). The thermal discomfort will increase in São Paulo due to climate changes (Batista et al, 2016) and the elderly can suffer with heat discomfort indoors (Alves, Duarte and Gonçalves, 2016) and cognitive problems (Trezza et al, 2015).…”