Overview: Can Chronic Pain Cause Alzheimer’s?
Both chronic pain and Alzheimer’s disease are most common in older adults, but new research suggests that these two issues may share a surprising connection. But how does that connection work? And how much of a risk is chronic pain when considering the possibility of neurodegenerative conditions like Alzheimer’s?
These are important questions, but first, let’s start with some background on Alzheimer’s and what sets it apart from normal age-related cognitive decline.
Alzheimer’s vs. Normal Aging
Beginning somewhere between the 50s and 70s, most people start to notice that they’re becoming more forgetful or can’t multitask as well as they used to. This may look like frequently misplacing keys, needing more time to remember names or events, or walking into a room only to forget why you came.
The good news is that for most people, this cognitive decline is normal and has no relation to any form of dementia. However, when these problems go from mild irritations to large hurdles that stop daily functions, neurodegenerative conditions may be the cause. If losing your keys is a sign of normal cognitive decline, then forgetting to pay bills or getting lost while driving in a familiar area are significant signs of dementia.
Now that we’ve got some background on the differences between normal aging and dementia, let’s dive into what the research has to say about the connection between chronic pain and severe cognitive decline.
The Connection Between Pain and Dementia
In a literature review published in the Journal of Neuroinflammation, the authors noted that individuals with chronic pain both self-rated themselves as having more severe cognitive decline and demonstrably showed higher incidences of loss in cognitive functions. Interestingly, this was true regardless of the type of pain that the participants lived with.
To account for this surprising result, the authors suggested that chronic pain may increase production of noradrenaline in certain parts of the brain, namely the prefrontal cortex and hippocampus, where decision-making ability and motor skills are housed. If true, this increase in noradrenaline could lead to inflammation in critical systems of the brain.
The team went on to posit that an inflammatory response could lead to a loss of synaptic function or even neuron death. In short, inflammation caused by chronic pain could damage or destroy parts of the brain that we rely on to communicate essential information, thus resulting in Alzheimer’s or other forms of dementia like Parkinson’s.
In theory, it wouldn’t take long for the inflammation to have these effects, either. Researchers suggested that pain lasting for at least three months could lead to abnormal cognitive decline via the inflammatory response.
Of course, these are all suppositions from a review of existing data, and thus may be subject to inaccuracies. In order to get a better understanding of the connection between Alzheimer’s and chronic pain, if one exists, we’ll have to look at other research and see how it compares to these suggestions.
Non-Cancer Chronic Pain and Alzheimer’s
In a separate study published by the International Journal of Environmental Research and Public Health, individuals with non-cancer chronic pain were more likely to report Alzheimer’s and other dementias in a follow-up two years later. This study included 11 groups that were studied from 2001 to 2013, with a total of 1,934 adults ages 65 and older. Of those, none of them had been diagnosed with or experienced symptoms of Alzheimer’s disease, and 36% of participants had non-cancer chronic pain.
Before calculating the association between chronic pain and Alzheimer’s, researchers had to adjust for certain factors like social demographics, various lifestyle habits, medications, and individual medical histories. But even after accounting for these relevant factors, there was still a significant association between non-cancer chronic pain and Alzheimer’s after two years. In fact, people with non-cancer chronic pain were 21% more likely to develop Alzheimer’s in that two years than their peers who did not report non-cancer chronic pain.
And for people with multiple types of chronic pain, the risk of developing Alzheimer’s increased dramatically. If an individual reported four or more types of non-cancer chronic pain, their risk for developing Alzheimer’s grew 91% when compared to people without any non-cancer-related pain.
Another study, this time published in Osteoarthritis Cartilage, found a similar association between chronic pain and dementia. In this retrospective study, researchers looked at a population of 25,009 individuals ages 65 year and older from 2009-2015 survey data. Of this number, 27% had osteoarthritis, and of that number, 47% reported pain that interfered with their daily lives.
After adjusting for personal factors in the individuals, those who reported pain that hindered daily activity were much more likely to develop Alzheimer’s or another form of dementia. Because this study featured a large population size from across the United States, and because it supported the evidence of other studies, there is good reason to believe that chronic pain has some sort of connection with severe cognitive decline, even if we’re not sure of the mechanism.
But now that we know, what steps can we take both to lower cognitive decline risks for individuals with chronic pain and to help individuals who already have chronic pain and dementia?
“use it or lose it.”
Lowering Risk of Cognitive Decline
Before we delve into ways to lower risk of cognitive decline, it’s important to remember that nobody is exactly sure of how cognitive decline, normal or otherwise, appears. And even if we understand how it happens in one individual, there is no guarantee that it will appear via the same mechanism in another. For these reasons, any efforts to reduce risk of cognitive decline, while evidence-based, should be treated as just that: lowering risk, not perfectly preventing decline.
With that said, a review study published in the Journal of Applied Biomedicine found several factors that were associated with lower incidences of cognitive impairment. These strategies were broken down into three categories: physical activities, cognitive training, and diet.
- Physical Activities: Cardiovascular exercises like aerobics and dancing were associated with lower risk of cognitive decline. When done in populations that are ages 65 or older, these physical activities should be fairly non-intensive and low-impact to offer the benefits of exercise without risking injury.
- Cognitive Training: Believe it or not, there is some evidence that mental activity could follow the rule of “use it or lose it.” Mentally stimulating activities like crossword puzzles, board games, and learning a new language were all associated with lower incidence of cognitive decline.
- Diet: While the mechanism is unclear, data does suggest that a healthier diet may reduce risk of dementia. Most experts recommend the Mediterranean diet, which is based on fresh fruits, vegetables, and lean protein found in fish.
All of these approaches may help lower an individual’s risk of severe cognitive decline. And that’s great news for people with chronic pain who have not yet developed a form of dementia, but what about those who already have?
Helping People with Chronic Pain and Dementia
Unfortunately, there is no known way to undo the damage associated with dementia. And according to a 2019 study published in Pain Therapy, older adults with chronic pain and cognitive decline face unique challenges that need to be addressed.
Notably, elders with chronic pain and dementia were less likely to report pain. And when they did report it, their physicians often underestimated its severity, misdiagnosed the cause, and/or did not provide adequate pain relief strategies.
So what can providers do differently? The researchers suggested that health care practitioners should ensure that they’re using proper pain evaluation methods to better improve their ability to treat pain without exposing patients to harmful drugs if they are not necessary. Moreover, they noted that treatment should include training caregivers to note a patient’s risk for comorbidities and monitor them over time.
While there is no way to undo a loss of cognitive function, these steps will prove crucial as efforts increase to provide a high quality of life to individuals living with both chronic pain and dementia.
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