Alzheimer’s disease is a progressive form of dementia that causes problems in memory, thinking and behavior. After sufficient progression, those suffering from it can face extremely difficulty when trying to conduct even simple tasks. Now, a new study from researchers from Vanderbilt University in Nashville suggests that the disease might also hinder people’s ability to recognize when they are in pain.

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The study spanned three years and examined two groups of adults aged 65 and older. One group consisted of patients with Alzheimer’s disease, while the other was a control group without dementia. Using a device to expose participants to various heat sensations, the researchers gathered self-reported pain levels from each individual and analyzed the results.

“We found that participants with Alzheimer’s disease required higher temperatures to report sensing warmth, mild pain and moderate pain than the other participants,” said Todd Monroe, an assistant professor at Vanderbilt’s School of Nursing and lead author of the study.

Interestingly, although the study found lessened pain recognition in those with Alzheimer’s disease, their pain tolerance remained the same as the control group.

“What we didn’t find was a difference between the two groups in reporting how unpleasant the sensations were at any level,” Monroe said. “While we found that their ability to detect pain was reduced, we found no evidence that people with Alzheimer’s disease are less distressed by pain nor that pain becomes less unpleasant as their disease worsens.”

The inability to detect pain can have a cascade of effects by allowing underlying health issues to go undetected and untreated, ultimately leading to serious problems in the body such as organ damage.

Since the researchers used participant reports to gauge pain levels, the neural mechanisms behind the changes in pain perception found in the study are still unclear. Further research is needed to better understand exactly how Alzheimer’s disease is connected to pain perception and how to help patients detect discomfort, especially when they begin to have difficulties with verbal communication

“As people age, the risk of developing pain increases, and as the population of older adults continues to grow, so will the number of people diagnosed with Alzheimer’s disease,” Monroe said. “We need to find ways to improve pain care in people with all forms of dementia and help alleviate unnecessary suffering in this highly vulnerable population.”

Journal Reference: Contact heat sensitivity and reports of unpleasantness in communicative people with mild to moderate cognitive impairment in Alzheimer’s disease: a cross-sectional study. 10 May 2016. 10.1186/s12916-016-0619-1