Frontotemporal Dementia
Frontotemporal dementia (FTD) is a group of neurodegenerative disorders that preferentially affect the frontal and temporal lobes of the brain. Unlike Alzheimer’s disease, FTD often begins with prominent changes in behavior, personality, or language rather than with memory loss, and tends to develop at a younger age. It is one of the more common causes of dementia in people under 65. Imaging plays an important role in diagnosis by showing characteristic patterns of atrophy in the frontal and temporal lobes and by helping to exclude other causes of cognitive and behavioral change.
What is it?
Frontotemporal dementia is a group of progressive neurodegenerative disorders that primarily affect the frontal and temporal lobes of the brain. The frontal lobes are responsible for personality, social behavior, judgment, motivation, planning, and aspects of language production. The temporal lobes contribute to language comprehension, recognition of objects and faces, and emotional processing. Damage to these regions explains why people with FTD often show prominent changes in behavior, personality, or language—rather than memory loss—as the earliest and most striking feature.
FTD is not a single disease but a family of related conditions. The two most commonly described main forms are behavioral variant FTD (bvFTD) and primary progressive aphasia (PPA). Behavioral variant FTD is characterized by early and progressive changes in personality and conduct, including disinhibition (such as inappropriate comments or impulsive behavior), apathy, loss of empathy, repetitive or compulsive behaviors, changes in eating habits (often a preference for sweets or carbohydrates), and impaired judgment. Primary progressive aphasia presents with a gradual decline in language abilities and is further divided into subtypes—including non-fluent/agrammatic, semantic, and logopenic variants—based on the pattern of language difficulty. FTD also overlaps with movement disorders such as progressive supranuclear palsy, corticobasal syndrome, and amyotrophic lateral sclerosis (ALS) in some patients.
The underlying biology of FTD involves abnormal accumulation of specific proteins in the brain, most commonly tau or TDP-43, with smaller numbers of cases related to other proteins. A substantial minority of patients have a family history of FTD, ALS, or related conditions, and several genes—including MAPT, GRN, and C9orf72—are associated with inherited forms.
Symptoms typically develop gradually over years. Family members often describe a person who is “not themselves anymore,” with changes in personality, motivation, social behavior, or empathy that can be mistaken initially for depression, midlife crisis, or other psychiatric conditions. Memory may be relatively preserved early on, which can be a clue distinguishing FTD from Alzheimer’s disease. In primary progressive aphasia, patients may have growing difficulty finding the right words, understanding language, or speaking fluently. As the disease progresses, more widespread cognitive impairment, behavioral changes, and motor symptoms can develop.
MRI of the brain is an important part of evaluating suspected FTD because it can show characteristic patterns of atrophy in the frontal and temporal lobes, often more on one side than the other, especially in earlier stages. MRI also helps exclude other causes of cognitive and behavioral change, such as strokes, tumors, hydrocephalus, or chronic blood collections. In specialized settings, FDG-PET can show reduced metabolism in the frontal and temporal lobes; amyloid PET can help distinguish FTD from Alzheimer’s disease (which generally shows amyloid deposition); cerebrospinal fluid analysis may add information; and genetic testing may be considered, particularly when there is a family history. Detailed neuropsychological testing helps characterize the pattern and severity of cognitive change.
Important to Know
There is currently no cure or disease-modifying therapy for frontotemporal dementia, but a great deal can be done to support patients and families. Management focuses on safety, supportive care, treatment of specific symptoms, and helping caregivers cope with often challenging behavioral changes. Care is typically coordinated by a multidisciplinary team that may include neurology (often with subspecialty expertise in cognitive or behavioral neurology), psychiatry, speech-language pathology, occupational and physical therapy, social work, and primary care.
Specific behavioral symptoms—such as agitation, compulsive behaviors, sleep disturbances, depression, or anxiety—may be addressed with non-pharmacologic strategies and, in some cases, carefully chosen medications. People with primary progressive aphasia often benefit from speech-language therapy and tools to support communication. Practical planning—around safety in the home, driving, finances, legal documents, and future care—is especially important and is best addressed early because FTD often affects judgment and decision-making before memory.
Caregiver support is essential. The personality and behavioral changes of FTD can be particularly difficult for families, and access to education, peer support groups, respite care, and specialized counseling can make a significant difference. Because FTD often affects younger adults, families may also face unique financial, employment, and family planning challenges that benefit from early attention.
Red flag symptoms include sudden severe confusion, sudden behavioral or personality change, sudden weakness or numbness, sudden difficulty speaking, severe headache, seizures, falls, hallucinations, or rapid worsening over days to weeks. These warrant urgent medical evaluation, as they may indicate stroke, infection, metabolic disturbance, or another condition that needs immediate attention.