Frontotemporal dementia
Frontotemporal dementia (FTD), also known as frontotemporal lobar degeneration, is a group of neurodegenerative disorders characterized by progressive changes in behaviour, personality, language, and executive functions. It is the second most common cause of dementia in individuals under the age of 65, after Alzheimer's disease.
Overview
Frontotemporal dementia primarily affects the frontal and temporal lobes of the brain, leading to the degeneration and loss of neurons in these regions. The symptoms of FTD can vary widely depending on the specific subtype and areas of the brain affected.
Types of Frontotemporal Dementia
Behavioural Variant Frontotemporal Dementia (bvFTD)
Behavioural variant frontotemporal dementia (bvFTD) is the most common subtype of FTD, accounting for approximately 50% to 60% of cases. It is characterized by changes in behaviour, personality, and social cognition. Common symptoms include:
- Social disinhibition and inappropriate behaviours
- Loss of empathy and sympathy
- Emotional blunting or apathy
- Impulsivity and lack of judgment
- Changes in eating habits and food preferences
- Language difficulties (less prominent compared to other subtypes)
Semantic Variant Primary Progressive Aphasia (svPPA)
Semantic variant primary progressive aphasia (svPPA) is characterized by progressive language impairment, specifically affecting word comprehension and semantic knowledge. Individuals with svPPA may have difficulty finding words, understanding the meaning of words and objects, and maintaining coherent conversations. Other features may include:
- Naming difficulties
- Word-finding pauses and substitutions
- Impaired object recognition
- Reading and writing impairments
Nonfluent/Agrammatic Variant Primary Progressive Aphasia (nfvPPA)
Nonfluent/agrammatic variant primary progressive aphasia (nfvPPA) is characterized by difficulties in speech production and grammar. Individuals with nfvPPA may exhibit the following symptoms:
- Speech hesitations, effortful speech, and slow rate of speech
- Grammatical errors and difficulties forming sentences
- Apraxia of speech (difficulty coordinating the movements for speech)
- Preservation (repetitive behaviours or words)
Other Subtypes
There are additional subtypes of FTD that are less common but still recognized:
- Frontotemporal dementia with motor neuron disease (FTD-MND): This subtype combines features of frontotemporal dementia and motor neuron disease, such as ALS (amyotrophic lateral sclerosis).
- Corticobasal syndrome (CBS): CBS is characterized by asymmetric motor symptoms, including limb rigidity, dystonia, and apraxia, as well as cognitive impairments.
- Progressive supranuclear palsy (PSP): PSP involves impairments in balance, eye movements, and coordination, along with cognitive changes.
Genetics and Pathology
Frontotemporal dementia can have both genetic and sporadic causes. Approximately 40% to 50% of cases have a family history of the disease, suggesting a genetic component. Mutations in several genes, including C9orf72, MAPT, and GRN, have been associated with familial forms of FTD.
The underlying pathology of FTD involves the accumulation of abnormal protein aggregates in the brain. In some cases, these aggregates are composed of tau protein (tauopathy), while in others, they consist of TDP-43 protein (TDP-43 pathology).
Diagnosis and Treatment
The diagnosis of frontotemporal dementia can be challenging due to its diverse clinical presentations and overlap with other neurodegenerative disorders. It often requires a comprehensive evaluation, including neurological examination, neuropsychological testing, brain imaging (MRI or PET scans), and genetic testing.
Currently, there is no cure for FTD, and treatment focuses on managing symptoms and providing supportive care. This may involve a multidisciplinary approach, including medication, behavioural interventions, and therapy to address specific cognitive and behavioural symptoms.
Notable Individuals Affected by Frontotemporal Dementia
- Alberto Lattuada: Italian film director who was diagnosed with frontotemporal dementia in 2011.
- Peter Falk: American actor known for his role as Columbo, who battled FTD in the later years of his life.
- Terry Pratchett: British author famous for his Discworld series, who was diagnosed with posterior cortical atrophy, a subtype of FTD.
- Robin Williams: American actor and comedian who experienced behavioral and cognitive changes associated with FTD before his death.
References
- Rademakers R, et al. (2012). Common variation in the C9orf72 gene is associated with frontotemporal dementia. Acta Neuropathol, 124(1), 77-87.
- Rohrer JD, et al. (2011). The heritability and genetics of frontotemporal lobar degeneration. Neurology, 77(10), 903-908.
- Piguet O, et al. (2011). Frontotemporal dementia. Handb Clin Neurol, 100, 521-535.
- Rascovsky K, et al. (2011). Sensitivity of revised diagnostic criteria for the behavioural variant of frontotemporal dementia. Brain, 134(Pt 9), 2456-2477.
