Alzheimer's Disease May Impact How Patients Perceive Pain
Michelle Milliken
Aches and pains can become more common as we get older. As we age, cognitive issues are also more common. A new study finds that those impacts to our brain could influence how we perceive those physical pains.
Research recently published in the journal Nature Communications investigated pain in mice with Alzheimer’s disease, finding that their bodies process pain signals in a different way than the bodies of healthy mice do. This suggests that Alzheimer’s patients experience changes in their perceptions of pain, which could call for a different approach to pain management in those with the disease.
Professor Marzia Malcangio, senior author and neuropharmacology professor at King’s College London, explains, “These are important findings, as untreated pain can contribute to the psychiatric symptoms of the disease. Increasing our understanding of this area could, with more research, lead to more effective treatments and ultimately improve people’s quality of life.”
To conduct their study, the team gave mice rheumatoid arthritis, which is an inflammatory disease. In healthy mice, the researchers observed increased levels of allodynia, pain caused by something that doesn’t usually produce pain. Immune cells in the brain called microglia also experienced increased activation in the spinal cord. These processes were regulated by the protein TLR4, which in healthy mice, receives pain signal transmissions from the protein Galectin-3 as it reaches the spinal cord.
However, in mice with Alzheimer’s, the immune cells in the central nervous system lacked TLR4, and so responded in a different way because the signals weren’t being picked up. As a result, these mice developed less pain stemming from joint inflammation, as well as a stunted immune cell response to pain signals received by the central nervous system.
The findings shine light on the issue of pain in Alzheimer's patients and may also help develop treatments.
George Sideris-Lampretsas, first author and PhD student at King’s, explains, “The results of this study have the potential to make an impact, not only by identifying Galectin-3/TLR4 as a potential therapeutic target for chronic pain, but most importantly by raising awareness around the underreported and untreated pain experienced by patients with AD.”
The Alzheimer’s Association says as Alzheimer’s progresses to the later stages, the patient may have difficulty expressing that they’re in pain. In that case, there are a few things you can look for as a caregiver or loved one: Physical signs like swelling, nonverbal signs like gestures or facial expressions, and changes in behavior like agitation or sleep disruption.
