Preservation of cognitive and functional ability as markers of longevity.

Longevity is a complex biological process for which the phenotypes have not been established. Preservation of cognitive and physical function may be important and preservation of these functions is, in part, inherited. We investigated the relation between rate of change in cognitive and functional abilities in probands and risk of death in their siblings. Probands were classified as showing no decline, slow, medium, or rapid rate of decline, based on the slope of change in cognitive and physical/functional factors over three or more assessments. Siblings of probands who did not decline on measures of memory, visuospatial/cognitive function or ADL skills were approximately half as likely to die as siblings of probands who had the most rapid decline. The reduction in risk of death in siblings of probands who did not decline in was primarily observed among siblings of probands who were older than 75 years, suggesting that genetic influences on life span may be greater at older ages. There was no association between probands' rate of change in language, IADL skills, upper or lower extremity mobility and risk of death in siblings. The results of the present study identify phenotypes associated with preserved cognitive and functional abilities which may serve as markers for longevity.