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Frontotemporal Dementia
Introduction
Frontotemporal dementia (frontotemporal lobar degeneration) is an umbrella term for a diverse group of rare disorders that primarily affect the frontal and temporal lobes of the brain — the areas generally associated with personality and behavior.
In frontotemporal dementia, portions of these lobes atrophy, or shrink. Signs and symptoms vary, depending upon the portion of the brain affected. Some people with frontotemporal dementia undergo dramatic changes in their personality and become socially inappropriate, impulsive or emotionally blunted, while others lose the ability to use and understand language.
Frontotemporal dementia is often 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, typically between the ages of 40 and 70. And the memory problems associated with Alzheimer's disease are not as prominent in the early stages of frontotemporal dementia.
Researchers estimate that at least 2 percent of all dementia cases are the frontotemporal variety. The disease appears to run in families — between 20 percent and 50 percent of people who have frontotemporal dementia have a family history of some type of dementia. After diagnosis, the course of the disease may run anywhere from two to 10 years before resulting in death.
Signs And Symptoms
Identifying precisely which diseases fall into the category of "frontotemporal dementia" presents a particular challenge to scientists. The signs and symptoms may vary greatly from one individual to the next. Researchers have identified several clusters of symptoms that tend to occur together and be dominant in subgroups of people with the disorder. More than one symptom cluster may be apparent in the same person.
Behavioral changes
The most common signs and symptoms of frontotemporal dementia involve extreme changes in behavior and personality. These include:
- Increasingly inappropriate actions.
- Euphoria.
- Lack of judgment and inhibition.
- Apathy.
- Repetitive compulsive behavior.
- A decline in personal hygiene.
- Lack of awareness of thinking or behavioral changes.
Some subtypes of frontotemporal dementia are marked by the impairment or loss of speech and linguistic abilities. For example, primary progressive aphasia is characterized by an increasing difficulty in using and understanding written and spoken language. People with another subtype, semantic dementia, utter grammatically correct speech that has no relevance to the conversation at hand.
Movement disorders
Corticobasal degeneration, another subtype of frontotemporal dementia, is characterized by signs and symptoms similar to those of Parkinson's disease, such as:
- Poor coordination.
- Rigidity.
- Impaired balance.
- Tremor.
- Muscle spasms.
People who have a hereditary condition called frontotemporal dementia with parkinsonism-17 also experience the signs and symptoms of Parkinson's disease.
When the typical behavioral problems of frontotemporal dementia occur with the signs and symptoms of amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease), the condition is frontotemporal dementia with motor neuron disease (FTD/MND). These motor symptoms include:
- Weakness.
- Muscle shrinkage.
- Muscle spasms.
- Swallowing difficulties.
A genetic component is at work in some subtypes of frontotemporal dementia. Three specific chromosomes have been linked to different varieties of the disorder. But at least half the people with frontotemporal dementia have no family history of dementia.
Because brain cells are difficult to obtain from a living person, researchers study the brains of people with frontotemporal dementia after they've died. This study shows that frontotemporal dementia typically has the following characteristics:
- Loss of nerve cells (neurons) in the frontal and temporal lobes.
- Deposits of damaged proteins inside of nerve cells.
- Shrinkage of the frontal lobes and temporal lobes.
Under the microscope, doctors also check brain tissue for evidence of abnormal varieties or amounts of a protein called tau — which can lead to the buildup of twisted strands of protein, called tangles, inside the brain cells. These tangles disrupt normal neuron activity and can result in cell death. Tangles occur commonly in Alzheimer's and in some forms of frontotemporal dementia.
Abnormal accumulations of other proteins, including one called TDP-43, also have been linked to frontotemporal dementia. TDP-43 has also been associated with amyotrophic lateral sclerosis (ALS), a neuromuscular disorder also known as Lou Gehrig's disease. This may help explain why ALS often occurs in people who have frontotemporal dementia.
Treatment
There's no cure for frontotemporal dementia and no effective way to slow its progression. Treatment relies on managing the symptoms and may include:
- Antipsychotics. Drugs that can block the effects of dopamine, a chemical messenger associated with psychosis, may be of value in managing aggressive, irrational and compulsive behaviors that may develop with frontotemporal dementia.
- Tranquilizers. If agitation or other types of hyperactivity become problems, small doses of tranquilizers may help.
- Speech therapy. People with primary progressive aphasia may benefit from therapy to help them adjust to their language difficulties and learn alternate ways to communicate.
Information obtained from National Institute of Health