The purpose was to describe clinical, cognitive, and personality characteristics at baseline assessment of 249 participants, 19 to 60 years of age, in a multinational longitudinal study of autosomal dominant Alzheimer¿s disease (ADAD). Method: Participants (74% cognitively normal) were from ADAD families with mutations in 1 of 3 genes (APP, PSEN1, or PSEN2). Mixed model analyses, including family as a random variable and controlling for years from expected time of symptomatic onset of ADAD based on parental age at onset, compared 3 groups (cognitively normal mutation noncarriers, cognitively normal mutation carriers, very mildly impaired mutation carriers). Results: Global cognitive deficits similar to those observed in late-life sporadic Alzheimer¿s disease (AD) existed in very mild ADAD compared with cognitively normal carriers and noncarriers on all but 2 measures (Digit Span Backward, Letter Fluency for FAS) of episodic memory, semantic memory, working memory, attention, and speeded visuospatial abilities. Demented individuals were less extraverted, open, and conscientious than cognitively normal participants on the International Personality Item Pool. Differences in the relation between 3 measures (Logical Memory, Digit Symbol, attention switching) and time to expected age at symptomatic onset indicate that cognitive deficits on some measures can be detected in mutation carriers prior to symptomatic AD, and hence should be useful markers in subsequent longitudinal follow-up. Conclusions: Overall cognitive and personality deficits in very mild ADAD are similar to those seen in sporadic AD. Cognitive deficits also occur in asymptomatic mutation carriers who are closer to the expected time of dementia onset.
