frontotemporal dementia

noun

variants also frontotemporal degeneration

: any of several degenerative brain diseases that are caused by progressive atrophic changes in the frontal or temporal lobes, that usually start in late middle age, that result in changes to behavior and personality (such as impulsiveness, social impropriety, and apathy) and typically impaired language function, and that lead in advanced cases to a profound decline in cognitive and language functioning

Alzheimer disease is the most common cause of dementia, but similar impairment of intellectual functioning occurs with many other brain disorders, such as frontotemporal dementia (FTD). After AD, FTD is the second most prevalent cause of early-onset dementia (occurring before age 65 years).

—M. J. Friedrich, Journal of the American Medical Association

Note: Pick's disease and sometimes progressive supranuclear palsy are classified as frontotemporal dementias.

—abbreviation FTD