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.
Source: IOS Press via EurekAlert
Trying to process that statement... they had *lower* sensitivity to pain but felt *more* unpleasantness? Did I not get enough sleep last night?
The thermal stimulation protocol used in the study assessed two aspects of pain: the intensity of pain and the unpleasantness of pain. The protocol was a modification of the perceptual matching experimental mechanical pressure pain protocol used by Cole and colleagues [24] and used the Medoc Q-Sense™. This device evokes simulation of A-delta and C-fibers [25, 26]. The Medoc thermode (30×30 mm) was attached to the thenar eminence of the right hand of each participant, and participants were shown a 0–20 sensory pain intensity scale and asked to stop the heat stimulus (via clicking a computer mouse) when they felt “just noticeable pain,” “weak pain,” or “moderate pain” (with each percept tested in separate trials). Participants were then asked to rate the unpleasantness of the sensation at each pain intensity percept using a 0–20 unpleasantness scale with the following anchors: “0 = neutral,” “5 = slightly unpleasant,” “8 = unpleasant,” “11 = very unpleasant,” “16 = intolerable,” and “20 = extremely distressing”[27].
I have a high pain threshold, my sensitivity is "turned down". I can perceive pain just fine as I 'listen' to my body and deal with arthritic pain daily. I think the researchers may be saying "High pain threshold, but dramatic about their perceived pain". You do not argue with those patients - yes their ‘sense’ of pain exceeds their physiologic reaction to painful stimuli.
Have you ever tried to compare pain levels with a post-childbirth woman? There are two types - those whose pain was intense, non-ending, but bearable, and those who would flay, draw, and quarter you to suggest any man could even understand the pain of childbirth. The difference? Perception of pain. I have provided anesthesia for childbirth and have cared for both types (spectrum) of women.