General information on FTD
Frontotemporal dementia, sometimes called frontotemporal lobar degeneration, was first described 100 years ago by Arnold Pick and was previously referred to as Pick’s disease. It is the second most common degenerative disease causing dementia in younger adults. The age of onset is typically in the 50s or 60s but can be as young as 30.
Damage to brain cells is more localised than in Alzheimer’s disease, and begins in the frontal and/or temporal lobe. In FTD the clinical presentation varies, depending on whether the frontal or temporal lobe is affected first. When the initial pathology affects the frontal lobes, the main changes are in personality and behaviour (Behavioural-variant FTD). Individuals with predominant temporal lobe involvement present with loss of language skills (Progressive Non-fluent Aphasia, Semantic Dementia) known as progressive aphasia (aphasia is the loss of the ability to produce or understand language).
The pathology of FTD is much more complex and variable than the pathology of Alzheimer’s disease. Instead of the ‘plaques and tangles’ which characterise Alzheimer’s disease, the brains of people with FTD brains show a severe loss of brain cells (neurons). In some individuals, the tau protein, which is also involved in Alzheimer’s disease, collects in neurons known as ‘Pick bodies’. Asmall proportion of people with tau accumulations have a mutation of the tau gene on chromosome 17. More commonly, the brains of people with FTD shows an accumulation of another cell protein – ubiquitin. Ubiquitin is involved in clearing waste products from brain cells but for reasons that are currently unknown, this protein builds up in some people with FTD. Very recent research has suggested that the accumulation of ubiquitin is attached to another protein (called TDP-43) which has a fundamental role in cell nuclei. Again, a small proportion of people with ubiquitin accumulation have a genetic mutation, this time of the progranulin gene which is also located on chromosome 17.
More on the specific subtypes of FTD, diagnosis and prognosis in the following sections and in the free Younger Onset Dementia booklet on the Alzheimer Australia website.
