These results suggest that frequent participation in cognitively stimulating activities is associated with reduced risk of AD.

The strong independent association between self-efficacy and function found in this study suggests that clinical programs in areas such as prevention, geriatric evaluation and management, and rehabilitation should attempt simultaneously to improve physical skills and confidence. Available knowledge of the factors influencing efficacy should guide the development of these efficacy-building programs.

Greater social resources, as defined by social networks and social engagement, are associated with reduced cognitive decline in old age.

The potential consequences of driving limitations or cessation should be taken into account when advising older drivers and developing alternative transportation strategies to help maintain their mobility.

These data provide strong evidence that the relation between senile plaques and level of cognitive function differs by years of formal education.

The results raise the possibility that depressive symptoms in older persons may be associated with risk of developing AD.

Proneness to experience psychological distress is a risk factor for AD, an effect independent of AD pathologic markers such as cortical plaques and tangles.

Social engagement is independently associated with depressive symptoms cross-sectionally. A longitudinal association is seen only among those not depressed at baseline.