Frontotemporal dementia with parkinsonism-17

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Frontotemporal dementia with parkinsonism-17 (FTDP-17) is a brain disorder. It is part of a group of conditions, called frontotemporal dementia or frontotemporal degeneration, that are characterized by a loss of nerve cells (neurons) in areas of the brain called the frontal and temporal lobes. Over time, a loss of these cells can affect personality, behavior, language, and movement.

The signs and symptoms of FTDP-17 usually become noticeable in a person's forties or fifties. Most affected people survive 5 to 10 years after the appearance of symptoms, although a few have survived for two decades or more.

Changes in personality and behavior are often early signs of FTDP-17. These changes include a loss of inhibition, inappropriate emotional responses, restlessness, neglect of personal hygiene, and a general loss of interest in activities and events. The disease also leads to deterioration of cognitive functions (dementia), including problems with judgment, planning, and concentration. Some people with FTDP-17 develop psychiatric symptoms, including obsessive-compulsive behaviors, strongly held false beliefs (delusions), and false perceptions (hallucinations). It may become difficult for affected individuals to interact with others in a socially appropriate manner. They increasingly require help with personal care and other activities of daily living.

Many people with FTDP-17 develop problems with speech and language. They may have trouble finding words, confuse one word with another (semantic paraphasias), and repeat words spoken by others (echolalia). Difficulties with speech and language worsen over time, and most affected individuals eventually lose the ability to communicate.

FTDP-17 is also characterized by problems with movement that worsen over time. Many affected individuals develop features of parkinsonism, including tremors, rigidity, and unusually slow movement (bradykinesia). As the disease progresses, most affected individuals become unable to walk. Some people with FTDP-17 also have restricted up-and-down eye movement (vertical gaze palsy) and rapid abnormal movements of both eyes (saccades).

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

FTDP-17 is caused by mutations in the MAPT gene. This gene is located on chromosome 17, which is how the disease got its name.

The MAPT gene provides instructions for making a protein called tau. This protein is found throughout the nervous system, including in neurons in the brain. It is involved in assembling and stabilizing microtubules, which are rigid, hollow fibers that make up a cell's structural framework (the cytoskeleton). Microtubules help cells maintain their shape, assist in the process of cell division, and are essential for the transport of materials within cells.

Mutations in the MAPT gene disrupt the normal structure and function of tau. The defective protein forms abnormal clumps within neurons and other brain cells. However, it is unclear what effect these clumps have on cell function and survival. FTDP-17 is characterized by the gradual death of cells in the frontal and temporal lobes of the brain. The frontal lobes are involved in reasoning, planning, judgment, and problem-solving, while the temporal lobes help process hearing, speech, memory, and emotion. A loss of cells in these brain regions leads to personality changes, speech difficulties, and the other features of FTDP-17.

FTDP-17 is one of several related diseases known as tauopathies, which are characterized by an abnormal buildup of tau in the brain.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

The worldwide prevalence of FTDP-17 is unknown. In the Netherlands, where the disease prevalence has been studied, it is estimated to affect 1 in 1 million people. However, the disorder is likely underdiagnosed, so it may actually be more common than this estimate.

FTDP-17 probably accounts for a small percentage of all cases of frontotemporal dementia.

Which doctor should you see?

The suggested department for discussing Frontotemporal dementia with parkinsonism-17 is Neurology, with a neurologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Frontotemporal dementia with parkinsonism-17. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.