Résumé : Semantic Dementia (SD) is a subject of a rich literature, but few large series are available. We report the demographics and neuropsychological data of a cohort of 82 patients followed prospectively for 20 years. Semantic Dementia begins before age 65 in 75 % of cases, but we have hold this diagnosis in two subjects over 80 years. In accordance with the classification of the French consensus of 2008, initially 71 % of patients could be classified as typical SD with an isolated, multimodal semantic memory impairment. 11 % could be classified as atypical SD due to pure verbal semantic impairment and 18 % as atypical SD because of the existence of discrete extralinguistic disorders (type 2). Two years later, 28.5 % of typical SD exhibited extralinguistic disturbances and all initial pure verbal SD exhibited multimodal semantic memory impairment.
Although classified as a
subtype of progressive aphasia,
SD is more than a semantic verbal deficit in the vast majority of cases.