Semantic dementia

Semantic dementia (SD) is a progressive neurodegenerative language disorder characterized by fluent, empty speech and loss of word meaning. SD is one of three clinical syndromes associated with frontotemporal lobar degeneration. SD is a clinically-defined syndrome, but it is sometimes anatomically defined as the temporal variant of frontotemporal lobar degeneration (tvFTLD).

Signs and Symptoms
SD patients complain of word-finding difficulties. Neuropsychology testing reveals deficits in picture naming, category fluency (e.g. "Please list as many animals as you can in one minute") and non-verbal tasks where the patient is given three photos and asked to point to a semantically related pair (known as "the pyramid and palm tree task," in which the third item is a pine tree). As the disease progresses, behavioral and personality changes are often seen similar to those seen in frontotemporal dementia.

Anatomy
SD is associated with gray matter atrophy in the temporal poles (usually left more than right), insula, and ventromedial and orbitofrontal cortex.