Frontotemporal dementia is caused by circumscribed degeneration of the frontal and temporal lobes of the brain. There is atrophy of the prefrontal and anterior temporal neocortex. Four different histological changes have been described and are associated with different clinical features.A small proportion of people with frontotemporal dementia have Pick disease in which Pick bodies (protein tangles) and ballooned neurons are seen on brain histology. Pick bodies are sometimes found in neurons beyond the frontal and temporal lobes.
Pick disease, and a number of other causes of frontotemporal dementia, are caused by genetic abnormalities.