Frontotemporal Dementia

What causes Frontotemporal dementia?

Frontotemporal dementia is caused when nerve cells in the frontal and/or temporal lobes of the brain die and the pathways that connect them change. There is also some loss of important chemical messengers. Over time, the brain tissue in the frontal and temporal lobes shrinks.


The main subtypes of FTD are called:

  • Behavioural variant FTD or bvFTD.
  • Primary progressive aphasia or PPA.

PPA can be further split into two main subtypes known as:

  • semantic dementia or SD.
  • progressive nonfluent aphasia or PNFA.

Behavioural variant FTD (bvFTD), presenting with changes in personality and social behaviour, and with difficulties in reasoning and planning.

Semantic dementia (SD), characterised by loss of understanding of concepts and facts, and problems in finding the right words or in losing the meaning of words.

Progressive nonfluent aphasia (PNFA); aphasia means a difficulty with speaking or language. In PNFA the meaning of words is preserved, but the patient has difficulties in producing speech, because of either difficulties with grammar or in planning how to move the muscles to articulate words.

A third subtype of PPA is also sometimes included called Logopenic aphasia (LPA). Patients with language problems usually show greater loss of brain tissue on the left side of the brain than on the right.


Behavioural variant FTD (bvFTD) symptoms include:

Behavioural symptoms

  • Change in motivation.
  • Development of inappropriate social behaviours.
  • Developing obsessive compulsive traits.
  • Loss of empathy.
  • Change in appetite.

Cognitive symptoms

  • Impairment in executive function (e.g. planning, decision making).

Semantic dementia (SD) symptoms include:

  • Difficulty finding the right word – People may use another word instead of the correct one, for example saying ‘cat’ instead of ‘dog’, or calling something a ‘thing’ or other vague term.
  • Losing understanding of what words mean – People may ask the meaning of a word that they have previously known.
  • Talking about things in a vague manner – People may not seem to be making any sense when they speak.
  • Difficulty understanding what other people are saying – Sometimes this can be put down to people seeming to be ‘deaf’.
  • Problems with reading.
  • Problems with spelling.

Progressive non-fluent aphasia (PNFA) symptoms include:

  • Slow, hesitant speech.
  • Difficulty finding the right word to say.
  • Pronouncing words incorrectly.
  • ‘Telegraphic’ speech.
  • Producing the wrong grammar.
  • Saying the opposite word to the one they mean to say.
  • Problems with reading.
  • Problems with spelling.

Life expectancy

The average survival time after symptoms start is around eight years.

Additional Information

FTD Talk provide a number of really helpful fact sheets  about Frontotemporal dementia.

Familial Frontotemporal dementiaFrontotemporal dementia prognosis

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