[Diagnostic profile of young-onset dementia before 65 years. Experience of a French Memory Referral Center].

OBJECTIVE

The aim of the study was to compare the profiles of patients with young (age≤65 years) and late (age>65 years) onset of dementia in a memory clinic of a Memory Referral Center in Lyons (France), for the year 2008.

METHODS

A total of 746 demented patients were evaluated using clinical, neuropsychological and imaging information. For each patient, diagnoses of the dementing disorder used clinical criteria at the first visit. We examined the distribution of patients diagnosis and differences in sex and education between the young-onset dementia (YOD) and the late-onset dementia (LOD) groups.

RESULTS

From a total of 746 registered demented patients (300 men, 446 women), there were 91 patients (12.2%) with YOD (from 36.5 to 65 years) and 655 patients with LOD (from 66 to 92 years). Among the 91 YOD patients, the most frequent causes were Mild Cognitive Impairment (MCI) (18.7%), then Alzheimer's disease (AD), frontotemporal dementia and posterior cortical atrophy (14.3% each), followed by progressive aphasia (11.0%), dementia with Lewy bodies (DLD) (9.9%), semantic dementia (8.8%), other causes (3.3%), vascular dementia (2.2%), undetermined dementia (2.2%), AD+cerebrovascular disease (1.1%). Among the 655 LOD patients, AD was the most frequent cause of dementia (57.4%). Referred cases by a specialist doctor were 50.5% in the YOD group and 12.7% in the LOD group (P<0.0001). In the ACP group, 68.4% patients began before 65 years.

CONCLUSION

The number of YOD in our memory clinic was four-fold the number of expected patients in France. The characteristics of the Referral Center explain the high frequency of rare dementia such as progressive aphasia (5.2% of overall number), semantic dementia (3.6%) and posterior cortical atrophy (2.5%).