Researchers suggest changes in a person's sense of humor may be an early sign of frontotemporal dementia or Alzheimer's disease.
Researchers from University College London (UCL) in the UK found that people whose sense of humor became darker with age were more likely to have behavioral variant frontotemporal dementia (bvFTD) - a form of frontotemporal dementia (FTD) characterized by changes in behavior - and that this change in humor began years before disease onset.
FTD is the most common form of dementia among people in their 50s. Unlike with Alzheimer's disease, memory problems are not a highly prominent symptom of the condition.
The researchers also found that changes in sense of humor may also be an early sign of Alzheimer's - the most common form of dementia overall, affecting around 5.3 million Americans.
Study leader Dr. Camilla Clark, of the Dementia Research Centre at UCL, and colleagues recently published their findings in the Journal of Alzheimer's Disease.
To reach their findings, the team asked the friends and relatives of 48 people with various forms of FTD or Alzheimer's and 21 healthy individuals to complete a number of questionnaires about their loved one's sense of humor.
The questionnaires asked friends and family to rate their loved one's liking for different comedy styles, including slapstick comedy, satirical comedy and absurdist comedy.
The friends and relatives were also asked whether they had noticed any changes in their loved one's sense of humor in the previous 15 years - long before they were diagnosed with dementia - and if they recalled any times that their humor was inappropriate.
Humor changes appeared 9 years before typical dementia symptoms
Compared with healthy individuals and those with Alzheimer's, the researchers found that people with bvFTD were more likely to have had inappropriate incidences of humor, including laughing at things other people would not normally find funny - such as a barking dog - and laughing at tragic events in their personal life and on the news.
In addition, the team found that people with bvFTD or Alzheimer's were more likely to prefer slapstick humor - such as the British sitcom Mr Bean - than satirical and absurdist humor, compared with similarly-aged healthy individuals.
The researchers report that the friends and relatives of people with bvFTD or Alzheimer's noticed changes in their loved one's sense of humor a minimum of 9 years before more common dementia symptoms presented, indicating that changes in humor may be an early sign of both FTD and Alzheimer's.
The team says their findings may lead to better dementia diagnosis by identifying alterations in sense of humor as a potential early indicator for the disease. Dr. Clark adds:
"These findings have implications for diagnosis - not only should personality and behavior changes ring alarm bells, but clinicians themselves need to be more aware of these symptoms as an early sign of dementia.
As well as providing clues to underlying brain changes, 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."
Dr. Simon Ridley, director of research at Alzheimer's Research UK, who helped fund the study, calls for larger studies that follow people for longer periods in order to pinpoint how and when a person's change in humor may be an indicator for dementia.
"Dementia diagnosis poses multiple challenges," he adds, "but through research we will be able to improve diagnosis and ultimately find treatments that tackle the specific causes of the condition."
Last month, Medical News Today reported on a study published in Neurology that suggested older women who complain of poor memory may be at greater risk for dementia nearly 20 years later.