Physical and Cognitive Activities as Deterrents of Cognitive Decline in a Biracial Population Sample

Objective: Physical and cognitive activities are associated with slower cognitive decline. Few studies have examined racial differences in these associations, however. The aim of this study was to examine the association of physical and cognitive activities with level and change in cognitive function among black and white participants. A secondary aim was to explore observed differences between black and white participants using post hoc analyses based on education and cognitive function levels. Methods: Data came from a longitudinal study of 7,742 (63% black and 61% female) participants assessed three times over an average of 9.5 years. At baseline, each participant reported number of hours of leisure time physical activity (categorized using quartiles) and rated frequency of participation in cognitively stimulating activities (range: 0-4). A standardized measure of cognition was derived from tests of memory, perceptual speed, and orientation. Results: Of the 7,742 participants, 2,322 (30%) reported no physical activity. Cognitive decline was slower by about 20% (95% CI: 13%-27%) among whites with physical activity above 1.25 hours compared with those with no physical activity, but showed no significant decrease in cognitive decline relative to those with no physical activity among blacks. Further post hoc analysis revealed cognitive decline to be slower by about 29% (95% CI: 20%-38%) among blacks and whites with higher education and above average baseline cognition. A 1-point increase in cognitive activity frequency decreased cognitive decline by 8% (95% CI: 3%-14%) among blacks and by 14% (95% CI: 7%-20%) among whites. Conclusions: The benefits of higher physical activity on cognitive decline was observed among whites, and among blacks with higher education and above average baseline cognitive function. Nevertheless, the protective effect of cognitive activity seems to be independent of education and baseline cognitive function among both blacks and whites.