Report by UCL polled relatives and found many said patients’ perception of what was funny changed dramatically and became ‘inappropriate and graphic’

An increasingly twisted sense of humour could be one of the early signs of dementia, a new study has found, including laughing at inappropriate moments.

The University College London research, published in the Journal of Alzeheimer’s disease, questioned the families and friends of 48 dementia patients, who had known them for more than 15 years before their disease took hold. Many of them noted that their relatives’ sense of humour had changed.

The study found patients laughed at “frankly inappropriate” moments, including watching news reports about natural disasters, or seeing a car parked badly. One recalled a relative laughing after a loved one badly scalded herself.

Dementia patients were likely to find satirical or absurdist comedy less funny than slapstick, such as Mr Bean, the study found. After the patients were diagnosed, respondents said that they noticed “a shift in patients’ comedy preferences toward the fatuous and farcical”.

All patient groups liked satirical and absurdist comedy significantly less than healthy patients, the study found.

It found an altered sense of humour is particularly common in two specific types of dementia: semantic dementia and a variety of frontotemporal dementia noted for causing sufferers to lose their inhibitions and struggle in social situations. A change in humour was also frequently found in patients with Alzheimer’s disease.

“Early on, [they] laughed very loudly at things that were only mildly funny, flippant or over the top; now [they] laugh all the time at things that are not particularly funny and will say ‘I’m laughing and I’m not sure why I’m laughing’,” one respondent wrote. “When I badly scalded myself the other year, [they] thought it was hilarious.”

“I have asthma – [they] laugh sometimes when I am fighting to get my breath,” another relative wrote.

Many said the person’s mature or cultured sense of humour had disappeared, with relatives laughing only at the most slapstick comedy or dirty jokes. “Used to be very witty but that has all gone; humour has to be more obvious, laughs if others laugh,” one wrote.

“[They have] little sense of humour at all, does not really find anything funny but will give a silly laugh or sneer when totally inappropriate,” another wrote. One said their relative’s humour was now “very rude and graphic, everything is now ‘funny’”.

Dr Simon Ridley, of Alzheimer’s Research UK, said relatives concerned about changes in the behaviour of their loved ones should contact their GP.

“While memory loss is often the first thing that springs to mind when we hear the word dementia, this study highlights the importance of looking at the myriad different symptoms that impact on daily life and relationships,” he told the BBC.

“A deeper understanding of the full range of dementia symptoms will increase our ability to make a timely and accurate diagnosis.”