Friends or relations of 48 people with different forms of frontotemporal dementia and Alzheimer's disease were asked to rate their preference for different kinds of comedy and how it had changed over 15 years. The researchers found that people with both types of dementia preferred slapstick humour to more cerebral satirical comedy, such as Yes Minister, or absurdist comedy, such as that of Monty Python and The Goon Show, even if they had previously been fans of more complex comedy.

New research suggests that a change in sense of humour can point to the onset of neurodegenerative disease.

People with frontotemporal dementia also appeared to develop a darker sense of humour, taking delight in other people's misfortunes. And when they made jokes they tended to be graphic, smutty or childish in their subject, according to the study. Many stopped laughing altogether. The same was not true of Alzheimer's sufferers.

While Alzheimer's disease is the leading cause of dementia, frontotemporal dementia is the most common cause of dementia in the under-55s.

Friends and relations reported seeing the changes in sense of humour for both forms of dementia an average of at least nine years before the start of more typical dementia symptoms such as memory loss.