Persistent pain that disrupts people's ability to work and carry out chores is linked with increased risk of cognitive impairment, a new study shows.
Experts estimate that roughly one in five older adults experience physical pain that lasts for three or more months. This persistent pain (a term used interchangeably with chronic pain) can have major effects on people’s daily lives, impacting their mobility, sleep, mood, social relationships and overall quality of life. The prevalence of pain-related conditions is on the rise, prompting scientists to turn their attention to developing a deeper understanding of how pain can affect our health — including brain health.
A new study published in the Journal of the American Geriatrics Society shows that the longer older adults live with pain, the more likely they are to develop cognitive impairment. In particular, for every additional two years of experiencing pain that gets in the way of day-to-day routines, people have 21 percent higher odds of being cognitively impaired.
According to cognitive aging and persistent pain researcher Tyler Bell, the study’s lead author, older adults are at higher risk of experiencing this type of pain than the general population, and yet, they are less likely to be screened and treated for their pain. He hopes that his team’s research will prompt better care for older adults when it comes to persistent or chronic pain.
“I’m hoping this study is reemphasizing that persistent pain is very common in older adults and has an important impact on one of the main factors that keeps your functional independence in life — your cognitive abilities,” Bell, postdoctoral scholar at the Department of Psychiatry, Center for Behavior Genetics of Aging at the University of California San Diego, told Being Patient.
Past research has shown that people with chronic pain tend to perform worse on cognitive tests, Bell explained. But it hasn’t been clear whether chronic pain is linked with cognitive impairment over time, or as people age.
So, Bell and colleagues analyzed data of more than 85,000 people aged 65 and older from the Health and Retirement Study. In the analysis, the researchers looked at participants’ answers to three questions about pain that were collected every other year for almost two decades: the presence of pain, pain intensity, and pain interference, meaning whether it disrupted the participant’s ability to work and perform household chores.
The team also analyzed participants’ performance in cognitive screening that included measures of episodic memory, attention/processing speed and vocabulary.
The researchers found that participants who reported having persistent pain experienced greater cognitive decline and an increased risk of cognitive impairment, compared to those without persistent pain. Further, those who reported pain interference also had worse cognitive performance over time and higher odds of cognitive impairment than participants without pain interference. For every additional two years of pain interference, people were 21 percent more likely to develop cognitive impairment.
For every additional two years of pain
interference, people were 21 percent more
likely to develop cognitive impairment.
Scientists have a few theories to explain the association between cognitive impairment and persistent or chronic pain: They suggest that neural networks in the brain may rewire themselves in response to chronic pain. As the brain compensates for processing pain, it devotes fewer resources for cognitive function, researchers posit. They also hypothesize that chronic pain can lead to brain inflammation, and in turn, accelerate brain aging, cognitive decline and even Alzheimer’s pathology.
But the biological mechanisms underpinning the link between cognitive impairment, neurodegeneration and chronic pain are still unclear. Accordingly, Bell and colleagues are currently taking a closer look at this association using methods like neuroimaging.
Meanwhile, the recent study has several limitations. For one, because this is an observational study, the team could not determine a causal link between cognitive impairment and chronic pain. It’s possible that cognitive impairment and chronic pain are actually two stand-alone symptoms of neurodegeneration, Bell noted. Further, drugs like opioids can affect people’s cognition and experience with pain, but he said the team did not have access to data regarding the type of medications participants may have used.
So, Bell and colleagues are now examining whether the recent study’s results can be replicated, and in particular, whether persistent or chronic pain can predict the likelihood of developing mild cognitive impairment.