Graduation Year


Document Type




Degree Granting Department

Aging Studies

Major Professor

Brent J. Small, Ph.D.

Co-Major Professor

Ross Andel, Ph.D.

Committee Member

Cathy L. McEvoy, Ph.D.

Committee Member

James A. Mortimer, Ph.D.

Committee Member

Huntington Potter, Ph.D.


Aging, Cognition, Dementia, Lifestyle, Diet, social resources


It is widely accepted that cognitive abilities decline with normal aging. At the same time it is also recognized that there is variability in the magnitude and rate of decline among aging individuals. A similar phenomenon exists for dementia, where individuals with similar neuropathologic burden present with varying degrees of cognitive impairment. Of importance is determining what factors account for this variability, and whether individuals can modify these factors in order to preserve their cognitive abilities with aging or delay the onset of dementia.

The purpose of this dissertation was to examine three potentially modifiable lifestyle factors' association with age-related differences/change in cognitive performance and risk for dementia by conducting three separate studies. The first study examined the association between engagement in lifestyle activities and concurrent cognitive speed performance. The second study examined whether there are differential associations between social resource factors and change in cognitive performance. The final study estimated the risk of late-life dementia in Swedish twins as a function of fruit and vegetable consumption in midlife.

Taken together, the results of these studies provide evidence that individuals may be able to protect themselves against age-related cognitive decline or dementia by modifying their lifestyle. Specifically, individuals may benefit their cognitive speed performance by engaging in more cognitively demanding activities. Declines in episodic memory performance may be alleviated by being more satisfied with social support, and declines in general cognitive performance and speed and attention in young-old adults may be attenuated by having a larger social network of friends. Finally, the risk of all types of dementia and Alzheimer's disease may be reduced by consuming a moderate amount of fruits and vegetables in the diet, especially for females, those with self-reported angina, and those who consumed alcohol in midlife. These findings contribute to the literature on potential strategies to maintain cognitive health with aging and serve as groundwork for future intervention studies.