Frontotemporal dementia is the second most common cause of dementia in people 65 years of age or younger. The disorder accounts for approximately 5–15% of all cases of dementia, with a prevalence of 10–15 per 100,000 subjects in the age group of 45–65 years. However, frontotemporal dementia is most likely underdiagnosed and the true incidence is probably higher. The disorder is most often seen in individuals in their 50s or 60s. It can occur much earlier, in individuals in their 20s, or as late as individuals in their 80s or older.

In most cases, frontotemporal dementia is not hereditary and the disorder occurs sporadically for unknown reasons. In such cases, the disorder does not run in families and is not expected to develop in other family members.

In some cases, there is a genetic component and a clear family history of the disorder. Often, the underlying cause of the disorder is unknown or not fully understood. There is likely an increased risk of developing the disorder in the affected family; although the exact nature or extent of the risk is unknown.

In rare cases, frontotemporal dementia is caused by a mutation in a specific gene that is inherited as an autosomal dominant trait. The most common of these genes are the MAPT and the GRN genes. Less often, mutations in other genes have been shown to cause frontotemporal dementia including the TARDBP, VCP, FUS and CHMP2B genes.

The signs and symptoms for frontotemporal dementia varies from one individual to another. It can easily be mistaken for a psychiatric disorder. Identifying the disease in an individual can be a challenge for the scientists and doctors. Frontotemporal dementia is generally broken down into three subgroups – a behavioral variant and two forms of primary progressive aphasia, the nonfluent variant and the semantic variant.

The behavioral variant is characterized by personality changes, a lack of restraint toward social conventions or behaviors (disinhibition), and a general lack of interest, enthusiasm or concern (apathy). This is the most common subtype of frontotemporal dementia.

Primary progressive aphasia is characterized by the slow onset and gradual progression of language difficulties. Individuals may have difficulty finding the right word or understanding certain words in written or spoken speech.

The nonfluent variant is characterized by slow, deliberate, sometimes halting speech patterns. Affected individuals may misuse words or omits words from speech (agrammatism). Individuals may have difficulty understanding sentences with complex structures. As the disease progresses, behavioral changes may develop.

Individuals with the semantic variant have difficulty understanding written and spoken speech, most prominently is an inability to understand single words. They may be unable to come up with the correct word to name an object, person or place, especially for words that are not commonly used. They may fail to understand specific words in speech. Early in the development of this subtype, the ability to understand complete sentences tends to remain preserved despite the inability to recognize individual words. As the disorder progresses, behavioral changes can occur including irritability, emotional withdrawal, insomnia, changes in eating habits, and depression.

Sometimes, frontotemporal dementia is associated with movement disorders including Parkinson’s disease or motor neuron disease. Other disorders that may be associated include corticobasal degeneration, progressive supranuclear palsy, and amyotrophic lateral sclerosis.

The diagnosis of frontotemporal dementia is clinical. A clinical diagnosis can be done by a physician with expertise with these disorder. It includes detailed examinations of changes in cognition, behavior, and personality. The behavioral form of frontotemporal dementia requires the exclusion of other potential causes of the characteristic symptoms. Primary progressive aphasia is a clinical diagnosis that usually requires a detailed patient history and neurological examination.

Frontotemporal dementia cannot be diagnosed in an individual through a single test. As a result, doctors must go through multiple tests including blood tests, neuropsychological tests, and brain scans. Blood tests allow doctors to examine whether an individual’s symptoms are being caused by a different condition.

Sometimes, a neuropsychological test may be performed on an individual. During this exam doctors are seeking an extensive assessment of reasoning and memory skills, and consequently this test takes a few hours to complete. The purpose of the neuropsychological test is to differentiate between the different types of dementias, which may be similar at an early stage of the disease.

Brain scans are often performed to identify visible abnormalities, including clots, bleeding, or tumors, which are signs and symptoms of the disease. Damage (atrophy) can also be seen on brain scans. Specific tests can include magnetic resonance imaging (MRI), computed tomography (CT) scans, and positron emission tomography (PET) scans.

Currently, there is no cure for frontotemporal dementia and no effective way of slowing down the progression of the disease. Treatment is aimed at managing the symptoms. Affected individuals are often prescribed medications based upon their specific symptoms. Such medications include antidepressants and antipsychotics, both of which are used which help to reduce behavioral issues.

Individuals may also choose therapy as a form of treatment as well. Individuals with frontotemporal dementia can also experience language difficulties and as a result, may benefit from speech therapy and learning alternative strategies to communicate with others.

In the early developmental stage of frontotemporal dementia, the symptoms can be treated fairly well. However, in the later stages, 24-hour supervision and care may become necessary for affected individuals.  

Advances in understanding the underlying causes of frontotemporal dementia has led to new therapeutic targets being explored and the possibility of developing effective disease-modifying drugs in the future.

Frontotemporal dementia is a condition that worsens over time. As a result, individuals affected by the disease are recommended to have caregivers that will assist them with daily activities.  In addition, affected individuals should avoid events or activities that trigger undesirable behavior. This may include maintaining a calm environment around them, being provided with structured routines, and simplifying their daily work.

Bang J, Spina S, Miller BL. Frontotemporal dementia. Lancet. 2015;386(10004):1672-1682.

Benussi A, Padovani A, Borroni B. Phenotypic heterogeneity of monogenic frontotemporal dementia. Front Aging Neurosci. 2015;7:171.

Frontotemporal Dementia; FTD. Online Mendelian Inheritance in Man (OMIM) website. http://www.omim.org/entry/600274  

Frontotemporal Disorders: Information for Patients, Families, and Caregivers. National Institute of Again. Available at: https://www.nia.nih.gov/alzheimers/publication/frontotemporal-disorders/introduction  

Frontotemporal Dementia. Mayo Clinic website. Available at: http://www.mayoclinic.org/diseases-conditions/frontotemporal-dementia/basics/definition/con-20023876

Pick Disease. National Organization for Rare Disorders (NORD) website. Available at: http://rarediseases.org/rare-diseases/pick-disease/.