Abstract
Dementia is an endemic affecting 44.4 million people worldwide in 2013 and will afflict 135.5 million by 2050. Alzheimer’s disease (AD) accounts for 60–80% of all dementias and cannot yet be prevented, slowed, or cured. Cardiovascular exercise training may attenuate AD’s course through its action on improving cardiovascular fitness which in turn mediates positive changes in brain structure and function. The purpose of this secondary data analysis was to examine the relationship between cardiovascular fitness and cognition in AD. Twenty-seven community-dwelling older adults with mild-to-moderate AD completed a 6-month, moderate intensity cycling intervention, 3 times a week in two pilot studies. Cardiovascular fitness and cognition were assessed using the intermittent shuttle walk test (ISWT) and AD Assessment Scale-Cognition (ADAS-cog), respectively, at baseline and 6 months. Data were analyzed using Pearson’s correlation and linear regression. Adjusted for age (79.3 ± 6.9 years), the 6-month change in ISWT has an inverse relationship with the 6-month change in ADAS-cog (r=-.40; p=0.04), indicating that enhanced cardiovascular fitness was associated with improved cognition over 6 months. The age-adjusted linear regression was also significant (F(2,24)=3.70, p=0.04, R(2)=0.24). Predicted change in ADAS-cog = 33.8 – 0.39 (Age) – 0.88 (change in ISWT). For each additional meter walked in the ISWT at 6 months, a participant’s ADAS-cog score improved 0.88 point. In conclusion, enhanced cardiovascular fitness may be essential for cardiovascular exercise to attenuate cognitive decline in individuals with AD. Future studies are needed to replicate these findings and further elucidate the physiological mechanism of exercise-induced neural protection.