Cardiovascular disease as a mediator in the relationship between lifestyle risk factors and cognitive outcomes: a scoping review

Abstract

Dementia is a major global health challenge and lifestyle modification is a key prevention strategy. Cardiovascular disease (CVD) is hypothesized to mediate lifestyle-dementia relationships, but empirical evidence is unclear. Mediation analysis offers insight into causal mechanisms beyond traditional associations. This scoping review synthesizes the limited available studies applying mediation analysis to examine whether CVD mediates associations between lifestyle factors (smoking, alcohol use, diet, physical activity) and cognitive outcomes in adults aged 45 and older. Of 1309 records screened, five studies met the inclusion criteria, reflecting a small, heterogeneous evidence base. Most examined physical activity (n = 4), with two reporting partial mediation by composite CVD risk scores. Evidence for diet (n = 2) and alcohol (n = 1) was inconclusive, and no studies assessed smoking. Overall, evidence for CVD as a mediator remains tentative, sparse, and inconsistent, highlighting major methodological gaps and an urgent need for robust studies to clarify whether cardiovascular health underpins lifestyle-related dementia risk. HIGHLIGHTS: Five studies were identified that used mediation analysis to explore the role of cardiovascular disease in the relationship between lifestyle risk factors and dementia. Cardiovascular disease may partially mediate the impact of physical activity on brain health. Diet and alcohol consumption showed no clear mediation effects by cardiovascular disease on cognition. Longitudinal, well-powered studies with robust mediation frameworks are urgently needed to evaluate vascular pathways and optimize dementia prevention strategies targeting modifiable lifestyle factors.

Plain Language Summary

• The question we studied: Because dementia and heart disease share similar lifestyle risk factors—such as smoking, drinking alcohol, poor diet, and lack of exercise—scientists are interested in whether heart disease might be the link between these habits and the risk of developing dementia. We explored the research on this topic so far and asked the question: Does heart disease play a role in the relationship between lifestyle risk factors (diet, physical inactivity, smoking, and alcohol consumption) and dementia?
• How we studied it: We reviewed existing research and included studies that investigated whether heart disease acts as a “middle step” between lifestyle habits and dementia in adults aged 45 years and older.
• What we found:  We only found five relevant studies. Most of them looked at physical activity and found that heart disease—especially stroke—may help explain how being activity protects brain health. However, results were unclear for diet and alcohol consumption, and we found no studies that targeted smoking. While there is some early evidence that heart disease may connect lifestyle habits to dementia risk, more research is needed.
• Why it matters: These findings suggest that improving heart health through lifestyle changes could also help protect brain health and reduce the risk of dementia. If future studies confirm these links, public health strategies focused on preventing cardiovascular disease could play a key role in slowing the rise of dementia.