It is a common belief that cognitively impaired people have reduced pain sensitivity. However, analysis of previous studies on pain responses in cognitively impaired patients has revealed that the experience of pain is elevated in patients with mild to moderate Alzheimer's disease.
Researcher Ruth Defrin from University of Tel Aviv, Israel, said, "It appears that those with widespread brain atrophy or neural degeneration...all show increased pain responses and/or greater pain sensitivity. However, individuals with cognitive impairment can have difficulty communicating the features of their pain to others, which in turn presents a significant challenge for effective diagnosis and treatment of their pain."
The researchers are unclear on the pain sensitivity in late Alzheimer's disease. They said, "The effects of other types of neurodegenerative impairment on pain processing appear variable. Pain responses seem to be decreased in patients with frontotemporal dementia and Huntington's disease, but increased in those with Parkinson's disease. Effects on pain sensitivity may vary even for diseases affecting similar areas of the brain."
The study was published in PAIN.