Early onset dementia: characteristics in a large cohort from academic memory clinics.

AIM: To describe the characteristics of early-onset dementia (EOD) in a cohort from 3 memory clinics. METHODS: We assessed all patients with dementia referred to the Academic Memory Clinics at Amiens, Lille, and Rouen University Medical Centers between 2005 and 2007. Patients aged less than 65 years at the time of onset of symptom were included in the EOD group, whereas older patients were included in the late-onset dementia (LOD) group. RESULTS: Three thousand four hundred and seventy-three patients (including 1932 women) were included and 811 (23.4%) were classified as EOD. The sex ratio was 1.12, whereas women were overrepresented in LOD (P=0.001). Patients with EOD were more frequently (P=0.001) living at home (87.3%), they had a lower educational level than the general population (P=0.0001) but were more educated (P=0.001). The current Mini Mental State Examination did not differ (P=0.3) between EOD (18.6±7.6) and LOD (18.9±6). The most common causes of EOD were Alzheimer's (22.3%) and vascular (15.9%) diseases and 4 pathologies that were significantly more frequent (P=0.001) than in the LOD group: frontotemporal dementia (9.7%), alcohol-related dementia (9.4%), traumatic brain injury (3.8%), and Huntington's disease (3%). CONCLUSIONS: EOD is characterized by specific features and different causes although Alzheimer's and vascular dementias remain the main causes of dementia in EOD.