LONDON, Nov. 11 (UPI) -- Already aware that dementia-related diseases cause changes in sense of humor, researchers at University College London found changes to what people find funny may indicate specific types of dementia years before other symptoms become apparent.
Alzheimer's disease is the most well-known and leading cause of dementia, bringing with it behavioral changes and memory problems. In patients with Alzheimer's, shifts in what patients laugh at are known to happen, as is typical in most diseases that cause dementia.
UCL researchers found differences in the complexity of comedy -- think Jim Carrey's slapstick humor compared to the more information- and language-based comedy of George Carlin -- appreciated by patients indicates differences between Alzheimer's disease and behavioral variant frontotemporal dementia, or FTD.
Researchers said the findings could eventually factor into methods of diagnosis, but already should "ring alarm bells" among family and clinicians who observe similar personality changes.
"As sense of humor defines us and is used to build relationships with those around us, changes in what we find funny has impacts far beyond picking a new favorite TV show," said Dr. Camilla Clark, a researcher at University College London, in a press release. "Subtle differences in what we find funny could help differentiate between the different diseases that cause dementia. Humor 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."
The researchers used surveys of friends and family to compare 21 healthy people with 48 who had one of four types of dementia: 15 had behavioral variant frontotemporal dementia (bvFTD); 7 had semantic dementia (SD); 10 had progressive nonfluent aphasia (PNFA), and 16 were diagnosed with Alzheimer's disease (AD).
The series of questionnaires given to friends and family asked them to rate the participants' appreciation for different types of comedy, specifically referring to popular British television shows such as the slapstick "Mr. Bean," satirical comedy shows like "Yes, Minister," and absurdist comedy such as "Monty Python." Researchers also asked about current comedy preferences, instances of inappropriate humor, and shifts in preference during the previous 15 years.
An appreciation for slapstick comedy was the same among all groups of participants, although all the patient groups liked satirical and absurdist comedy significantly less than the healthy participants. For many bvFTD, PNFA, and AD patients, the pattern of disliking satirical comedy was reported to have been seen before receiving a dementia diagnosis.
All of the patients with bvFTD and SD laughed at inappropriate times such as funerals, tragedy on the news or the weather, while about 40 percent of PNFA and AD patients laughed at the wrong time.
"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," said Dr. Simon Ridley, director of research at Alzheimer's Research UK. "We need to see larger studies, following people for extended periods of time, to understand how and when changes in humor could act as a red flag for underlying brain changes."