11th August 2024

Frontotemporal dementia

Overview of frontotemporal dementia

Frontotemporal dementia (FTD) is a syndrome that has a wide presentation that can be categorised into variants predominantly affecting behaviour or language. The peak incidence is between the ages of 45-65, and it affects both sexes equally. 40% of patients with FTD have a relevant family history.

In behavioural variants, there is a progressive history (usually verified by collateral) of deterioration in behaviour and cognition resulting in disinhibition, apathy, loss of empathy, hyperorality, perseveration and loss of executive functioning, with relative sparing of memory.

There are three language variants, termed collectively as primary progressive aphasias:

• Progressive non-fluent aphasia: impaired production of expressive speech with difficulties in repeating complex words or phrases, poor speech flow and fluency and incorrect grammatical formation of phrases with phonological substitutions for words. In early disease, recognition of objects and understanding of language is preserved.
• Semantic dementia: loss of semantic memory, i.e. naming of objects and understanding the meaning of words, but with production of language that is grammatically correct and fluent. Names of items are substituted with a generic reference such as ‘that thing’. Repetition of phrases is preserved, although comprehension can be impaired. In contrast with Alzheimer’s disease and in early stages, short-term memory for daily activities remains intact.
• Logopaenic aphasia: paucity of speech, particularly groping for words and inability to repeat phrases resulting from a deficit in working memory capacity.

Diagnosis of frontotemporal dementia

Imaging, either MRI or PET, shows frontal and/or anterior temporal atrophy or hypoperfusion, respectively. CSF examination excludes causes such as infection and inflammation, and Alzheimer’s disease.