Frontotemporal dementia, also known as frontotemporal degeneration, or frontotemporal neurocognitive disease, is a disease that includes several types of dementia involving the frontal and temporal lobes. Frontotemporal dementias are broadly defined as language or behavioral disorders. The three main subtypes or variant syndromes include the behavioral variant, formerly known as Pick's disease, and two variants of primary progressive aphasia, the semantic variant and the afluent variant. Two rare subtypes of frontotemporal dementia exist, called interneuronal interneuronal inclusion disease and basal body inclusion disease. Other related disorders include corticobasal syndrome and frontotemporal dementia with amyotrophic lateral sclerosis, also called FTD-ALS or FTD-MND. Frontotemporal dementia is a predominantly early-onset syndrome associated with frontotemporal lobar degeneration, characterized by progressive neuronal loss involving mostly the frontal or temporal lobes, with a typical loss of more than 70% of spindle neurons, while other types of neurons remain intact. Frontotemporal dementia was first described by Arnold Pick in 1892, and was initially called Pick's disease, a term now reserved only for the behavioral variant of frontotemporal dementia that shows the presence of Pick bodies and Pick cells. Second only to Alzheimer's disease in prevalence, frontotemporal dementia actually accounts for about 20% or less of degenerative dementias found at autopsy. Signs and symptoms typically appear in late adulthood, are most common between the ages of 45 and 65, and affect men and women roughly equally. Common signs and symptoms include significant changes in social and interpersonal behavior, apathy, blunted emotions, and deficits in expressive and receptive language. There is currently no cure for frontotemporal dementia, but treatments may help relieve symptoms. Frontotemporal dementia is early-onset and most often occurs before age 65, but can begin earlier, occurring after this age in 20%-25% of cases. It is the most common type of early-onset dementia. The International Classification of Diseases (ICD) classifies it as a disorder that affects the mental and behavioral aspects of the human being. Report the gradual onset of behavioral changes or language deficits and their progression several years before presenting to a neurologist.