Spicy food intake predicts Alzheimer-related cognitive decline in older adults with low physical activity

Abstract

A plausible association exists among spicy food consumption, physical activity, and Alzheimer's disease ( AD) or cognitive decline, but it remains poorly investigated. We aimed to examined the association between spicy food and AD-related memory decline or global cognitive decline in older adults under the moderating effect of physical activity. Total 196 non-demented older adults were included. Participants underwent comprehensive dietary and clinical assessments including spicy food intake, AD-related memory, global cognition, and physical activity. The strength of spicy food was stratified into three categories: `not spicy' (reference), `low spiciness', and `high spiciness'. Multiple linear regression analyses were performed to examine the relationships between spicy level and cognition. The spicy level was the independent variable in each analysis; it was entered as a stratified categorical variable using the three categories. We found a significant association between a high level of spiciness in food and decreased memory ( beta - 0.167, p < 0.001) or global cognition ( beta - 0.122, p = 0.027), but not non-memory cognition. To explore the moderating effects of age, sex, apolipoprotein E epsilon 4 allele-positivity, vascular risk score, body mass index, and physical activity on the associations between spicy level and memory or global cognition, the same regression analyses were repeated including two-way interaction terms between the spicy level and each of the six variables as an additional independent variable. An interactive effect was detected between a high level of spiciness in food and physical activity on the memory ( beta 0.209, p = 0.029) or global cognition ( beta 0.336, p = 0.001). Subgroup analyses showed that the association between a high level of spiciness in food and a lower memory ( beta - 0.254, p < 0.001) and global score ( beta - 0.222, p = 0.002) was present only in older adults with low physical activity, but not in older adults with high physical activity. Our findings suggest that spicy food intake is predictive of AD-related cognitive decline, i.e., episodic memory; this relationship is worsened by physically inactive lifestyle.