Semantic dementia

Semantic dementia (SD) is a progressive neurodegenerative disorder characterized by loss of semantic memory in both the verbal and non-verbal domains. The most common presenting symptoms are in the verbal domain however (with loss of word meaning) and it is therefore often characterized (incorrectly) as a primary language disorder (a so-called progressive fluent aphasia).

SD is one of the three canonical clinical syndromes associated with frontotemporal lobar degeneration. SD is a clinically-defined syndrome, but is associated with predominantly temporal lobe atrophy (left greater than right) and hence is sometimes called temporal variant FTLD (tvFTLD).

It was first described by Arnold Pick in 1904 but in modern times was characterised by Professor Elizabeth Warrington in 1975

Signs and Symptoms

SD patients often present with the complaint of word-finding difficulties. Clinical signs include fluent aphasia, anomia, impaired comprehension of word meaning, and visual associative agnosia (inability to match semantically-related pictures or objects). As the disease progresses, behavioural and personality changes are often seen similar to those seen in frontotemporal dementia...
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