Can a major risk factor for Alzheimer's be revealed by pain perception?
Given the difficulty in diagnosing the Alzheimer's, scientists are exploring all kinds of avenues when it comes to techniques that may reveal the disease in its early stages, and new research out of the University of Tennessee (UT) is a particularly interesting example. The study authors have investigated the way pain perception may vary in those susceptible to developing the disease, and have teased out some useful differences they hope could one day translate into an inexpensive diagnostic tool.
The work centers around a gene variant called APOE4, which recent studies have revealed to be a major risk factor for Alzheimer's, with those carrying one copy of the variant three times more likely to develop the disease. Led by UT's Dr Ray Romano, the new study explored how there might be a way to detect this variant in patients that is far simpler than carrying out genetic testing.
The scientists recruited 49 cognitively healthy subjects, 12 of who were known to have the APOE4 variant. This group was subjected to experimentally induced thermal pain stimuli, with their pain thresholds monitored along with their feelings of unpleasantness. Romano believes this is the first study exploring the connection between pain and APOE4 in healthy subjects.
This revealed that those with the high-risk variant had a "significantly lower" sensitivity to the pain than the other group, but did feel greater unpleasantness as a result. Because these subjects were cognitively healthy, this raises the prospect of using pain perception as a cheap, non-invasive way of detecting Alzheimer's before any symptoms occur, which is a key focus for researchers in the field. But the study had a small sample size and there are many questions to answer first.
"In this exploratory study, Dr. Romano demonstrated that healthy adults with a specific gene for developing late-stage Alzheimer's disease experience pain differently than people without the genetic marker," says study author Todd Monroe. "Next, we need to examine the brain's pain systems to determine why this may be occurring. If future studies confirm these results, findings may eventually translate into earlier screening in people at risk of developing Alzheimer's disease leading to more treatment options."
The research was published in the Journal of Alzheimer's Disease.