Semantic dysfunction in frontotemporal lobar degeneration.

Abstract

Semantic dementia, characterized by loss of word meaning and impaired face and object recognition, is one of the clinical manifestations of frontotemporal lobar degeneration and is associated with atrophy of the inferior and middle temporal gyri. Patients may present predominantly with problems in naming and understanding words, or in face and object recognition, the verbal or nonverbal predominance reflecting the accent of atrophy on the left or right temporal lobe. Behavioural changes may occur, although these have a more obsessional quality than is typically seen in frontotemporal dementia (FTD). However, overlap in clinical symptomatology of semantic dementia and FTD may occur with disease progression reinforcing the link between these clinical syndromes. Semantic dysfunction is poorly recognized and may be mistaken for the amnesia of Alzheimer's disease, yet may be important in explaining some of the behavioural characteristics seen in focal cerebral degeneration.