By Pat Anson, Editor
Chronic pain has long been associated with a variety of health problems, including depression, anxiety, insomnia, high blood pressure and an impaired immune system. Now there’s something else to worry about.
A large new study by researchers at UC San Francisco has found that older people with chronic pain experience faster declines in memory and are more likely to develop dementia, an indication that chronic pain could cause changes in the brain. The study, published in JAMA Internal Medicine, appears to be the first to make this association.
UCSF researchers analyzed data from over 10,000 participants aged 60 and over who were enrolled an ongoing national study of older Americans. Patients were surveyed about their pain and cognition in 1998 and 2000.
Those who said they were persistently troubled by moderate or severe pain declined 9.2 percent faster in tests of their memory and cognitive ability over the next 10 years than those who said they were not troubled by pain.
The patients who complained about persistent pain also had a 7.7 percent greater chance of developing dementia.
“A persistent report of moderate to severe pain, which may reflect chronic pain, is associated with accelerated cognitive decline and increased dementia probability in a large population-representative data set of elders,” wrote first author Elizabeth Whitlock, MD, a postdoctoral fellow in the UCSF Department of Anesthesia and Perioperative Care.
“Clinicians should be aware of this association, which persisted after extensive statistical adjustment for confounding health and demographic factors. Patients reporting ongoing pain may be at higher risk for current and incident cognitive impairment and physical debility.”
Whitlock says the additional loss of memory in participants who reported persistent pain suggests that they will have a harder time with daily living tasks, such as managing their medications and finances.
"Elderly people need to maintain their cognition to stay independent," she said. "Up to one in three older people suffer from chronic pain, so understanding the relationship between pain and cognitive decline is an important first step toward finding ways to help this population."
The data that the researchers analyzed did not include information about opioid use, so researchers could not tell which of their participants were taking opioid painkillers. While opioid use could be the cause of the cognitive changes, so could the pain itself. For example, a recent study of chronic pain sufferers found that those who took non-steroidal anti-inflammatory drugs (NSAIDs) had nearly the same increased dementia risk as those taking opioids.
"This means we have to consider the potential direct effects of chronic pain on cognition," Whitlock said.
People who suffer from chronic pain tend to have diminished attention and impaired memory, and Whitlock says when pain is severe it could divert enough attention to interfere with the consolidation of memory. Another possibility is that the emotional stress of being in pain activates stress-hormone pathways in the body that have been implicated in cognitive decline. If either is the case, she said, then effectively treating the pain could protect cognition.
"This is something I really feel we can do something about as clinicians," Whitlock said. "It's part of taking care of the whole patient."