Overview

Frontotemporal dementia is an umbrella term for a group of brain disorders that primarily affect the frontal and temporal lobes of the brain. These areas of the brain are generally associated with personality, behavior and language.

In frontotemporal dementia, portions of these lobes shrink (atrophy). Signs and symptoms vary, depending on which part of the brain is affected. Some people with frontotemporal dementia have dramatic changes in their personalities and become socially inappropriate, impulsive or emotionally indifferent, while others lose the ability to use language properly.

Frontotemporal dementia can be misdiagnosed as a psychiatric problem or as Alzheimer's disease. But frontotemporal dementia tends to occur at a younger age than does Alzheimer's disease. Frontotemporal dementia often begins between the ages of 40 and 65 but occurs later in life as well. FTD is the cause of approximately 10% to 20% of dementia cases.

Symptoms

Signs and symptoms of frontotemporal dementia can be different from one individual to the next. Signs and symptoms get progressively worse over time, usually over years.

Clusters of symptom types tend to occur together, and people may have more than one cluster of symptom types.

Behavioral changes

The most common signs of frontotemporal dementia involve extreme changes in behavior and personality. These include:

  • Increasingly inappropriate social behavior
  • Loss of empathy and other interpersonal skills, such as having sensitivity to another's feelings
  • Lack of judgment
  • Loss of inhibition
  • Lack of interest (apathy), which can be mistaken for depression
  • Repetitive compulsive behavior, such as tapping, clapping or smacking lips
  • A decline in personal hygiene
  • Changes in eating habits, usually overeating or developing a preference for sweets and carbohydrates
  • Eating inedible objects
  • Compulsively wanting to put things in the mouth

Speech and language problems

Some subtypes of frontotemporal dementia lead to language problems or impairment or loss of speech. Primary progressive aphasia, semantic dementia and progressive agrammatic (nonfluent) aphasia are all considered to be frontotemporal dementia.

Problems caused by these conditions include:

  • Increasing difficulty in using and understanding written and spoken language, such as having trouble finding the right word to use in speech or naming objects
  • Trouble naming things, possibly replacing a specific word with a more general word such as "it" for pen
  • No longer knowing word meanings
  • Having hesitant speech that may sound telegraphic
  • Making mistakes in sentence construction

Motor disorders

Rarer subtypes of frontotemporal dementia are characterized by problems with movement similar to those associated with Parkinson's disease or amyotrophic lateral sclerosis (ALS).

Motor-related problems may include:

  • Tremor
  • Rigidity
  • Muscle spasms or twitches
  • Poor coordination
  • Difficulty swallowing
  • Muscle weakness
  • Inappropriate laughing or crying
  • Falls or walking problems

Causes

In frontotemporal dementia, the frontal and temporal lobes of the brain shrink. In addition, certain substances accumulate in the brain. What causes these changes is usually unknown.

There are genetic mutations that have been linked to frontotemporal dementia. But more than half of the people who develop frontotemporal dementia have no family history of dementia.

Recently, researchers have confirmed shared genetics and molecular pathways between frontotemporal dementia and amyotrophic lateral sclerosis (ALS). More research needs to be done to understand the connection between these conditions, however.

Risk factors

Your risk of developing frontotemporal dementia is higher if you have a family history of dementia. There are no other known risk factors.