In the most common form of dementia, it is not memory loss but behavioural changes that are first observed. One of these include a shift in sense of humour. Courtesy TheArches via Flickr

A change in sense of humour could be an early sign of dementia, says a study from UCL. This includes laughing at normal things like a badly parked car, a barking dog or inappropriate laughing at tragic events.

The findings are expected to help improve dementia diagnosis by going beyond memory loss and highlighting other changes linked to onset of dementia. It will also help differentiate between different diseases causing dementia, say the researchers.

The study looked at both people with behavioural variant frontotemporal dementia (bvFTD) and others with Alzheimer's. The former had a distinct altered sense of humour compared to the latter or healthy persons which included events others did not find funny.

Frontotemporal dementia is the most common cause of dementia in the under-55s. People with FTD normally develop behavioural changes before they suffer memory loss. The team wanted to look at these changes and the underlying brain changes.

Slapstick humour favoured

In both the bvFTD and Alzheimer's cases, people tended to prefer slapstick humour to satirical and absurdist humour when compared with healthy people of a similar age. Some of these changes in preference were seen on an average at least nine years before the start of more typical dementia symptoms.

Dr Camilla Clark, who led the research at the UCL Dementia Research Centre, said: "We've highlighted the need to shift the emphasis from dementia being solely about memory loss. These findings have implications for diagnosis – not only should personality and behaviour changes ring alarm bells, but clinicians themselves need to be more aware of these symptoms as an early sign of dementia. Humour could be a particularly sensitive way of detecting dementia because it puts demands on so many different aspects of brain function, such as puzzle solving, emotion and social awareness."

A series of questionnaires given to friends or relatives of 48 people with different forms of FTD and Alzheimer's measured the loved one's liking for different kinds of comedy ranging from slapstick Mr Bean, satirical like Yes, Minister or absurdist comedy such as Monty Python.

"A deeper understanding of the full range of dementia symptoms will increase our ability to make a timely and accurate diagnosis. We need to see larger studies, following people for extended periods of time, to understand how and when changes in humour could act as a red flag for underlying brain changes," said Dr Simon Ridley, Director of Research at Alzheimer's Research UK, adding that anyone who is concerned about changes in their behaviour "should speak to their GP".

The study was funded by Alzheimer's Research UK, the Wellcome Trust, the Medical Research Council (MRC) and NIHR Queen Square Dementia Biomedical Research Unit.

Dementia is caused by gradual changes and damage in the brain leading to the shrinking of the brain, says the NHS. The most common causes of dementia include diseases in which the brain cells degenerate and die more quickly than as part of the normal ageing process. This happens due to a build-up of abnormal proteins in the brain.