Patients with dementia and other forms of cognitive impairment have altered responses to pain, with many conditions associated with increased pain sensitivity, concludes an Israeli review.
The authors said the available evidence they looked at questioned the previous view that people with cognitive impairment had reduced pain sensitivity to pain.
“It appears that those with widespread brain atrophy or neural degeneration…all show increased pain responses and/or greater pain sensitivity,” said Ruth Defrin, from the University of Tel Aviv.
Dr Defrin and colleagues analysed previous studies on pain responses in cognitively impaired patients.
She said: “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.
“Because of those communication issues, it has even been suggested that cognitively impaired people have reduced pain sensitivity,” she added.
The researchers said the evidence suggested that normal, healthy aging may be associated with increased vulnerability to pain, as well as slightly reduced cognitive performance.
These changes may set up a “vicious circle”, with pain leading to a decline in cognitive function and vice versa, they said in the journal Pain.
“Individuals with cognitive impairment can have difficulty communicating the features of their pain”
Most studies suggest that the experience of pain is elevated in patients with mild-to-moderate Alzheimer’s disease, they concluded, though they added that pain sensitivity in late Alzheimer’s disease was unclear.
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.
Various developmental disabilities – such as autism, cerebral palsy, and intellectual disability – are also associated with increased pain sensitivity. As in other groups of patients with communication difficulties, alternative ways of assessing pain are needed.
Pain processing also appears to be affected in patients with various types of brain damage, such as stroke and traumatic brain injury. Recent studies have demonstrated brain responses to pain stimuli even in severely brain-damaged patients in a vegetative state.
The researchers said they hoped their review will increase awareness of possible changes in pain perception and processing and promote better approaches to pain management in people living with cognitive impairment.