Relation of age and apolipoprotein E to cognitive function in Down syndrome adults.

To test the cognitive effects of aging and apolipoprotein E (APOE) in individuals at high risk for Alzheimer's disease (AD), we assessed APOE genotypes and performance on a battery of neuropsychological tests in 41 non-demented, Down syndrome (DS) adults. Old DS subjects (ages 41-61 years) showed poorer memory and orientation scores than young DS adults (ages 22-38 years), but the groups did not differ in other measures after we controlled for intellectual function. Language ability was inversely related to APOE genotype, even after age was controlled for, with the presence of the epsilon 2 allele corresponding to better language skills than epsilon 4. Age-related cognitive changes in non-demented DS adults are consistent with the early effects of AD. The relationship between basic linguistic skills and APOE genotype supports this genetic factor in influencing the development of dementia and AD neuropathology in DS.