Neuropsychological performance in early and late onset Alzheimer's disease: comparisons in a memory clinic population.

OBJECTIVES

To compare the neuropsychological performance associated with early and late onset Alzheimer's disease (AD), in order to identify differences and compare these with previous reports.

METHODS

Patients attending a memory clinic were given a detailed multi-disciplinary diagnostic assessment, including a battery of neuropsychological tests. From those meeting ICD-10 criteria for Alzheimer's disease (AD), an early-onset (EO) group (n = 40) and a late-onset (LO) group (n = 90) were identified, and their performances compared. Patients with mixed dementia and co-morbid depression were excluded.

RESULTS

After adjustment, the EO and LO groups performed at a comparable level on the majority of the neuropsychological tests. The LO group performed better on the WAIS digit span test, AMIPB Complex Design and the written picture description, and the EO group performed better on the WAIS similarities test and the Boston naming test.

CONCLUSIONS

These findings suggest that, after adjusting for overall dementia severity and pre-morbid IQ, there is greater fronto-parietal/right hemisphere involvement in early-onset AD, and greater temporal/left hemisphere involvement in late-onset AD. This may be due to different genetic risk profiles for AD at different ages.