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A new study published in Neurology, the medical journal of the American Academy of Neurology looked at physical and mental activity, disease susceptibility, and risk of dementia.

“In the present study, we aimed to assess the associations between physical and mental activity and the subsequent risk of dementia,” study author Huan Song told us. “We further hoped to explore whether such associations would differ for individuals with different susceptibility to dementia.”

A growing body of evidence supports the role of physical activity in maintaining cognitive capacity and preventing dementia, with possible explanations including the release of brain-derived neurotrophic factors, the improvement of cerebral blood flow, and antioxidant effects in physical activity. In addition, social isolation might directly result in cognitive inactivity or faster cognitive decline, as well as indirectly influence functions of the brain through increasing the risk of cardiovascular disease and depression.

“Therefore, we expected to see the protective effects of some studied physical and mental activities on dementia,” Song told us. “But the key question is among various activities, which are the ones that benefit us the most, particularly considering the inherent high correlation and interactions between multiple modes of activity (e.g., persons who are physically active tend to have high levels of many types of physical activities)? Also, it remains unknown if the beneficial role of activities can be modified by diseases susceptibility to dementia.”

The treatment for dementia is still limited so far. Researchers wanted to know if some easy changes, such as adopting a healthier lifestyle, can be effective interventions for the primary prevention of dementia. Physical activity was assessed by 21 items from the well-validated, short self-reported International Physical Activity Questionnaire (IPAQ) at recruitment, and researchers considered mental activity as conditions related to intelligence, social contact, and electronic device use.

“We assessed the associations between individual items of physical and mental activity, as well as patterns of physical and mental activity identified by the principal component analysis, and dementia occurred at least one year after the activity information collection using Cox regression models,” Song told us. “Such analyses indicated people who were highly engaged in activity patterns including frequent exercises, household chores, and daily visits of family and friends had 35%, 21%, and 15% lower risk of dementia, respectively, compared to people who were the least engaged in these activity patterns.”

Disease susceptibility plays an important role in the development of dementia. In the current study, researchers assessed the disease susceptibility to dementia in multiple ways, including the level of polygenetic risk score (PRS) or APOE genotype (i.e., measures of disease susceptibility based on gene) and family history of dementia (i.e., the heritability of the phenotype). As they got similar findings when performing separate analyses for subgroups of participants with different disease susceptibility to dementia, their findings underscore the universal importance of physical and mental activity in reducing the risk of dementia.

“We found that activity patterns more adherent to frequent strenuous and other exercises, housework-related activity, and friend/family visits were associated with a reduced risk of multiple types of dementia, and such a protective role may be appliable to all people, irrespective of their disease susceptibilities to dementia,” Song told us. “Our findings highlight the potential of these physical and mental activity patterns, as effective interventions, in the primary prevention of dementia.”

Researchers also noticed there were some differential results from item-specific and pattern-based analyses which may indicate some effects of specific activity were actually due to its high correlation with the other activities.

“Take watching TV as an example,” Song told us. “The increased dementia risk associated with this activity cannot be confirmed in the pattern-based analyses, namely, individuals with a longer time of watching TV have a higher risk of developing dementia possibly due to their low engagement level of other mental activities, not watching TV itself. We therefore consider the pattern-based analyses convey a clearer message about the studied association, than item-based analyses.”

Researchers hope the results of this study encourage further work on the development of exercise programs to prompt the early prevention of dementia, particularly for the aging population. Also, researchers are interested in studying the possible biological mechanisms that link physical activity to various health consequences.