Frontotemporal dementia, also known as frontotemporal lobar degeneration, is a general designate for an assorted group of uncommon disorders that primarily affect the frontal and temporal lobes of the brain. These areas of the brain are typically associated with personality, behavior and language. In frontotemporal dementia, portions of these lobes shrink (atrophy). Signs and symptoms vary, depending upon the area of the brain affected. Some people with frontotemporal dementia experience dramatic changes in their personality and become socially inappropriate, impulsive or emotionally indifferent, while others lose their ability to utilize language. Frontotemporal dementia is often misdiagnosed as a psychiatric problem or as Alzheimer's disease; however, frontotemporal dementia tends to occur at a younger age than Alzheimer's disease, commonly between the ages of 40 and 45.
It has long been a particular challenge for scientists to identify specifically which diseases fall into the category of frontotemporal dementia. The signs and symptoms may differ significantly from one individual to another. Researchers have characterized several clusters of symptoms that have a tendency to arise together and are dominant in subgroups of people with the condition. In addition, several symptom clusters may be evident in the same person. The signs and symptoms of frontotemporal dementia progressively worsen with time, virtually always over years. Eventually, those afflicted will require 24-hour care.
The most frequent signs and symptoms of frontotemporal dementia involve extreme changes in behavior and personality. These include:
Some subtypes of frontotemporal dementia are discernable by the impairment or loss of speech and associated language difficulties. Two types of primary progressive aphasia are considered frontotemporal dementia. Primary progressive aphasia is characterized by an increasing difficulty in using and understanding written and spoken language. For example, people may have trouble finding the right word to use in speech or naming objects.
Rarer subtypes of frontotemporal dementia are characterized by issues with movement, similar to those associated with Parkinson's disease or amyotrophic lateral sclerosis.
Movement-related signs and symptoms may include:
In frontotemporal dementia, the frontal and temporal lobes of the brain shrink. Frequently, the cause of this disorder is unknown. Though several different gene mutations have been linked to particular subtypes of frontotemporal dementia, typically more than half of the people who develop frontotemporal dementia have no documented family history of dementia.
Frontotemporal lobar degeneration is separated into two main subtypes, one involving the buildup of a protein called tau in the brain and one involving the protein TDP-43 in the brain. In some instances, the affected parts of the brain contain microscopic abnormal tau protein-filled structures that develop within brain cells (Pick bodies). Frontotemporal dementia was once referred to as Pick's disease, but now that terminology is reserved for the subtype that specifically features these abnormal structures. Recently, researchers have confirmed mutual genetics and molecular pathways amongst frontotemporal dementia and amyotrophic lateral sclerosis (ALS). The significance of these correlations is currently being explored.
A person’s risk of developing frontotemporal dementia is escalated if they possess a family history of dementia. Otherwise, there are no other known risk factors.