London, May 31 (IANS): People with Alzheimer's disease and other forms of cognitive impairment (CI) may be more sensitive to pain, says a study.

"It appears that those with widespread brain atrophy or neural degeneration...all show increased pain responses and/or greater pain sensitivity," said one of the researchers Ruth Defrin from University of Tel Aviv, Israel.

The researchers analysed previous studies on pain responses in cognitively impaired patients.

Most studies suggest that the experience of pain is elevated in patients with mild to moderate Alzheimer's disease.

"However, individuals with CI 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 wrote.

Because of those communication issues, the belief that cognitively impaired people have reduced pain sensitivity may have formed.

Pain sensitivity in late Alzheimer's disease is unclear, the researchers noted, adding 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.

Various developmental disabilities -- such as autism, cerebral palsy, and intellectual disability--are also associated with increased pain sensitivity, the study said.

The findings suggests that pain processing is frequently altered in cognitively impaired individuals, often with increased sensitivity to painful stimuli.

The research review was published in the journal PAIN.