An analysis of diversity in the cognitive performance of elderly communitydwellers: Individual differences in change scores as a function of age

This longitudinal study investigated whether age is associated with increas es in interindividual variability across 4 ability domains using a sample o f 426 elderly community dwellers followed over 3.5 years. Interindividual v ariability in change scores increased with age for memory, spatial function ing, and speed but not for crystallized intelligence for the full sample an d in a subsample that excluded dementia or probable dementia cases. Hierarc hical regression analyses indicated that being female, having weaker muscle strength, and having greater symptoms of illness and greater depression we re associated with overall greater variability in cognitive scores. Having a higher level of education was associated with reduced variability. These findings are consistent with the view that there is a greater range of resp onses at older ages, that certain domains of intelligence are less suscepti ble to variation than others and that variables other than age affect cogni tive performance in later life.