Why pain can go untreated in people with Alzheimer’s

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There’s evidence that people with Alzheimer’s disease report pain less frequently compared to healthy adults. They also receive less pain medication.

But what isn’t clear is if people with Alzheimer’s perceive less pain, have an inability to recognize it, or can’t communicate that they are in pain.

“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.”

To find out, researchers studied pain responses in two groups of older adults (age 65 and older), one composed of healthy individuals and the other composed of people with clinical diagnoses of Alzheimer’s disease. The three-year study used a psychophysical thermal stimulation to test for and examine self-reports of pain in the two groups. The participants with Alzheimer’s were all physically healthy, verbally communicative, and able to provide a verbal pain rating.

“We compared the perception threshold for three experimental heat pain intensities and the reports of unpleasantness associated with each,” says Todd Monroe, an assistant professor at Vanderbilt University School of Nursing. “We found that participants with Alzheimer’s disease required higher temperatures to report sensing warmth, mild pain, and moderate pain than the other participants.

“What we didn’t find was a difference between the two groups in reporting how unpleasant the sensations were at any level.”

That the participants in both groups reported similar unpleasantness in the presence of mild and moderate pain appears to refute a longstanding hypothesis that pain tolerance is altered in people with Alzheimer’s, he says.

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“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,” Monroe adds.

Further study is still needed, he says, but it is becoming increasingly clear that health care providers should evaluate whether a patient with Alzheimer’s disease is in pain by using a variety of methods, including pain scales, behavioral changes, and nonverbal responses such as facial expressions. This will be especially critical in the latter stages of the disease when many patients have difficulty communicating.

“We are in the process of analyzing the neuroimaging data from this study, which we hope will further elucidate changes in the neurobiology of pain in Alzheimer’s disease.”

“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,” he says. “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.”

Other researchers from Vanderbilt and Royal Melbourne Hospital collaborated on the study, which was supported by the John A. Hartford Foundation, Mayday Fund, Vanderbilt Office of Clinical and Translational Scientist Development, Vanderbilt Clinical and Translational Research Scholars Program, and the NIH National Institute on Aging. The findings were published recently in BMC Medicine.

Source: Vanderbilt University