Dr's Casebook: Frontotemporal dementia (FTD) is rare and tends to start at a younger age

Bruce Willis has been diagnosed with frontotemporal dementia. Photo: Getty Images

Dr Keith Souter writes: I researched it and the other varieties of dementia quite extensively a few years ago when I was writing my book Understanding Dementia.

This condition used to be known as Pick’s disease, after its discoverer, Dr Arnold Pick. A professor of psychiatry at Prague, in 1892 he described a condition in which there is atrophy of the frontal and temporal lobes of the brain, resulting in dementia. The condition causes only two per cent of all new cases of dementia in the UK.

The two areas of the brain that are mainly affected by this condition have major functions in shaping our personalities, so behavioural disorders and personality changes may be seen in this dementia.

This condition can be extremely difficult to diagnose, because it often occurs at an earlier age than other dementias. Whereas most dementias occur after the age of 65 years, frontotemporal dementia tends to start between the ages of 45 and 65 years.

It can start considerably earlier, with cases having occurred in people in their twenties, and it can also occur in elderly people in their seventies and eighties. There are two frontal lobes of the brain, both of which are situated at the front behind the forehead. These are where reasoning, calculation, problem solving and judgement take place. Thus, they are command areas of the brain for behaviour. Broca’s area, a part of the brain which controls speech, is usually in the frontal lobe.

The temporal lobes are found at the sides of the brain. These are mainly concerned with memory, although are also associated with emotions and speech. Wernicke’s area, which controls language recognition, is usually located in the left hemisphere.

When these important parts of the brain suffer from nerve cell damage and loss of cells, the lobes shrink and the functions associated with them gradually deteriorate.

There are actually several variants of frontotemporal dementia that can be seen. The type that Bruce Willis is suffering from seems to be progressive non-fluent aphasia where speech fluency is particularly affected. A most distressing symptom for an actor.