Physical activity, cognitive activity, and cognitive decline in a biracial community population.

BACKGROUND

Findings from studies investigating whether physical activity reduces the risk of cognitive decline in old age have been inconsistent.

OBJECTIVE

To examine whether participation in physical activity by older adults reduces the rate of cognitive decline after accounting for participation in cognitively stimulating activities.

DESIGN

A prospective population study conducted from August 1993 to January 2003, with an average follow-up of 6.4 years.

SETTING

A biracial community population on the south side of Chicago.

PARTICIPANTS

Participants were 4055 community-dwelling adults 65 years and older who were able to walk across a small room and had participated in at least 2 of the 3 follow-up assessments.

MAIN OUTCOME MEASURE

Annual rate of cognitive change as measured by a global cognitive score, which consisted of averaged standardized scores from 4 cognitive tests.

RESULTS

In a mixed model adjusted for age, sex, race, and education, each additional physical activity hour per week was associated with a slower rate of cognitive decline by 0.0007 U/y (P = .04). However, with further adjustments (1) for participation in cognitive activities (beta = .0006, P = .10), (2) for depression and vascular diseases (beta = .0005, P = .19), and (3) by excluding participants whose global cognitive score at baseline was at or below the 10th percentile (beta = .0002, P = .45), the coefficients were smaller and no longer statistically significant.

CONCLUSION

These data do not support the hypothesis that physical activity alone protects against cognitive decline among older adults.