Better Cardiovascular Fitness in Mid-Life Correlates with Lower Risk of Later Dementia
People who maintain cardiovascular fitness as they age exhibit an onset of degeneration and age-related disease that takes place more slowly than that of their peers. This includes a much lower risk of dementia, as illustrated by the study data noted here, indicating the strong influence of the cardiovascular system on brain function. Firstly, the brain is an energy-hungry organ, and worse circulation leads to worse function quite directly. Separately, cardiovascular fitness tends to correlate with a lesser degree of hypertension with age. The raised blood pressure of hypertension causes damage to brain tissue and vessels in the brain, and a consistently lower level that damage makes a noteworthy difference over time. Distinctly again, the exercise needed to maintain physical fitness produces greater cell maintenance activities, leading to a slower accumulation of many forms of cell and tissue damage that contribute to to onset of dementia.
Very few studies have explored the patterns of cardiovascular health (CVH) metrics in midlife and late life in relation to risk of dementia. We examined the associations of composite CVH metrics from midlife to late life with risk of incident dementia. This cohort study included 1,449 participants from the Finnish Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study, who were followed from midlife (baseline from 1972 to 1987; mean age 50.4 years; 62.1% female) to late life (1998), and then 744 dementia-free survivors were followed further into late life (2005 to 2008). We defined and scored global CVH metrics based on 6 of the 7 components (i.e., smoking, physical activity, and body mass index [BMI] as behavioral CVH metrics; fasting plasma glucose, total cholesterol, and blood pressure as biological CVH metrics) following the modified American Heart Association (AHA)'s recommendations. Then, the composite global, behavioral, and biological CVH metrics were categorized into poor, intermediate, and ideal levels. Dementia was diagnosed following the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria.
During the follow-up examinations, dementia was diagnosed in 61 persons in 1998 and additional 47 persons in 2005 to 2008. The fully adjusted hazard ratio (HR) of dementia was 0.71 and 0.52 for midlife intermediate and ideal levels (versus poor level) of global CVH metrics, respectively; the corresponding figures for late-life global CVH metrics were 0.60 and 0.91 . Compared with poor global CVH metrics in both midlife and late life, the fully adjusted HR of dementia was 0.25 for people with intermediate global CVH metrics in both midlife and late life and 0.14 for those with midlife ideal and late-life intermediate global CVH metrics. Having an intermediate or ideal level of behavioral CVH in both midlife and late life (versus poor level in both midlife and late life) was significantly associated with a lower dementia risk, whereas people with midlife intermediate and late-life ideal biological CVH metrics had a significantly increased risk of dementia.
In this study, we observed that having the ideal CVH metrics, and ideal behavioral CVH metrics in particular, from midlife onwards is associated with a reduced risk of dementia as compared with people having poor CVH metrics. Maintaining life-long health behaviors may be crucial to reduce late-life risk of dementia.