Early-onset Alzheimer's disease is associated with a distinct neuropsychological profile

Abstract

Alzheimer's disease (AD) mostly occurs in the elderly. Nevertheless, AD also occurs in younger patients (i.e. ≤ 65 years old) and often has a different clinical manifestation. This study examined whether neuropsychological performance in patients with early onset AD differed from patients with late onset AD. In 172 Patients with AD (81 early onset and 91 late onset) cognition was assessed using a battery of neuropsychological tests. These tests were combined into five cognitive domains (memory, language, attention, executive functioning and visuo-spatial functioning). Global cognitive functioning was assessed using Mini-Mental State Examination (MMSE) and Cambridge Cognitive Examination (CAMCOG). Univariate analyses of variance were performed with age of onset as between-subjects factor, and sex and education as covariates. In patients with early onset AD age (mean±SD) was 60±4 years, 54% were female. In patients with late onset AD age was 72±5 years, 52% were female. Global cognition did not differ between early (MMSE:20±5, CAMCOG:69±15) and late onset AD (MMSE:21±5, CAMCOG:70±15) (p = 0.2 and p = 0.25). Patients with early onset AD performed worse on tasks demanding attention (p < 0.001), executive functioning (p < 0.001) and visuo-spatial functioning (p < 0.001) than patients with late onset AD. Patients with late onset AD performed worse on memory than patients with early onset AD, but this was not significant (p = 0.11). We found no differences in language (p = 0.21). Patients with early onset AD presented with a different profile of cognitive impairment than patients with late onset AD. In patients with early onset AD visuo-spatial functioning, attention and executive functioning were more severely impaired, while memory was relatively spared.