The much-loved actor Robin Williams, who suffered from chronic depression and committed suicide last year, was revealed recently to also be afflicted with Lewy body dementia.
His widow, Ms Susan Williams, said in an interview earlier this month that before he took his own life, he probably had only three years to live.
Recent research and figures from overseas post-mortem studies suggest Lewy body dementia may be more common than people think.
It occurs in 10 to 25 per cent of those diagnosed with dementia, and could be the second- or third-most common form of dementia after Alzheimer's, said Associate Professor Reshma Merchant, a geriatrician at the National University Hospital (NUH).
In Lewy body dementia, protein deposits, called Lewy bodies, develop in nerve cells in regions of the brain involved in thinking, memory and motor control.
In a Singapore study released earlier this year, it was found that one in 10 people here aged 60 and above has some form of dementia.
As people live longer, the prevalence of dementia is likely to increase as well, said Prof Merchant, who also heads the division of advanced internal medicine at NUH.
Symptoms of Lewy body dementia may fluctuate - as often as moment to moment, hour to hour or day to day - in 50 per cent to 80 per cent of patients, said Prof Merchant. Nine in 10 patients experience gait or walking abnormalities and Parkinsonism in the early stages of the condition.
Parkinsonism is any condition that causes a combination of the movement abnormalities seen in Parkinson's disease, such as tremor, slow movement, impaired speech or muscle stiffness.
About half of such patients can exhibit "dream enactment" behaviour. This includes talking, yelling, punching, kicking, jumping from bed and flailing of the arms, said Prof Merchant.
Psychotic symptoms - where the person's thinking and emotions indicate that he has lost touch with reality - can occur in around eight in 10 patients. Other symptoms include an unexplained temporary loss of consciousness, as well as sleep disorders.
People with Lewy body dementia are worse off than those with Alzheimer's in terms of cognitive function, such as working memory and visuo-spatial skill, which is the visual perception of spatial relationships among objects.
Memory deterioration may not be very obvious in the early stages. In the middle and late stages of Lewy body dementia, it is sometimes difficult to differentiate the condition from Alzheimer's .
There are no treatments which can stop or slow brain cell damage caused by dementia with Lewy bodies. A few medications have some beneficial effects on the person's behaviour.
The average life expectancy of those diagnosed with Lewy body dementia after symptoms first appear is seven years, said Prof Merchant. Some, though, may live up to 20 years, she added.
In general, Lewy body dementia progresses more rapidly than Alzheimer's. As with any type of dementia, exercise, diet and control of other chronic diseases can help to prevent it, though more studies are needed in this area.
Prof Merchant provides tips on how to make things easier for someone with Lewy body dementia, which may also be applicable to those with other forms of dementia:
•Have predictable routines, especially around meal, shower and sleep times.
•Establish a night-time ritual - for example, having a warm drink, using aromatherapy or dimming of lights. There should be no loud noises or flashing lights from the TV set.
•Break tasks into small parts. Focus on the successful completion of each task.
•Go for walks with the person to create a sense of empowerment and independence for him.
•Ensure that the person can hear and see properly, so that he can interact with others and participate in conversations.