LAUSR

BACKGROUND Alzheimer's disease (AD) is a heterogeneous pathology. Young patients with AD are particularly likely to have an atypical presentation. The objectives of the present cluster analysis were to determine whether patients with early-onset Alzheimer's disease (EOAD) had several distinct cognitive profiles and to compare the resulting clusters with regard to clinical, neuroimaging and laboratory characteristics. METHODS We collected cognitive, behavioural, functional, neuroimaging and laboratory data on 72 patients meeting the criteria for probable mild EOAD. The patients were first classified into clinical phenotype groups by a multidisciplinary board of clinicians. The patients' cognitive and functional decline was monitored for 24 months. A k-means clustering analysis was then used to determine clusters on the basis of the patients' neuropsychological test results. RESULTS Two distinct clusters were identified: the patients in the first cluster (C1, n=38) had a predominant memory impairment, whereas patients in the second (C2, n=34) did not. Dyslipidaemia and the presence of ɛ4 APOE allele were more frequent in C1, whereas the cognitive and functional decline was faster in the patients in C2. Moreover, posterior brain abnormalities were more severe in patients in C2 than in patients in C1. CONCLUSION By applying a k-means clustering analysis, we identified two clusters of patients in an EOAD cohort. The clusters differed with regard to certain clinical, imaging and laboratory characteristics. This clustering procedure might be of value for managing patients with EOAD in general and for identifying those at risk of more rapid decline in particular.