Chronic pain, from conditions such as arthritis and back pain, increases the risk of dementia and accelerates cognitive decline, according to new research.
Further, when people have chronic pain in more than one part of the body – say, the knee, neck and lower back – the rate of cognitive decline is even faster.
These accelerated deficits include impaired memory, executive function, learning, and attention.
Chronic pain is pain that last for at least three months.
Hippocampus shrinkage
Key to this research were measurements of the hippocampus in pain-riddled and pain-free participants aged in their 60s.
While the brain overall shrinks with age, the hippocampus – a region of the brain vital for learning and memory functions – shrinks faster than other regions.
Accelerated shrinkage of the hippocampus is an early indicator of Alzheimer’s disease.
The latest research
In the new study, scientists from the Chinese Academy of Sciences, Beijing, analysed the records of 354,943 people in the UK Biobank cohort.
They found that the risk of neurocognitive abnormality increased with each additional pain site.
In short, the rate of shrinkage (a measurement of ageing) was linked to the number of sites (parts of the body) where participants suffered with chronic pain. The more places in pain, the greater the shrinkage.
In a person aged 60 with one site of chronic pain, the hippocampus was seen to age by about a year.
In a person with two pain sites, the hippocampus visibly aged by more than two years.
The hippocampus in people with pain in five or more body sites had shrunk to the equivalent of up to eight years of ageing.
“Multi-site chronic pain may lead to up to eight years of accelerated hippocampal ageing, an effect that may underlie a series of cognitive burdens,” said Dr Tu Yiheng, from the academy’s Institute of Psychology.
The study provides “a quantitative understanding of the impact of chronic pain on cognitive function and the risk of dementia, laying an important foundation for future research into the relationship between chronic pain and cognitive impairment.”
Significant memory reduction
The relationship of chronic pain to cognitive decline is complex and controversial.
In 2007, researchers confirmed that chronic pain doesn’t just cause physical discomfort; it can impair memory and concentration.
Two-thirds of participants with chronic pain showed significant disruption to their memory and attention span when tested.
But was the disruption more psychological or was it evidence of biological dysfunction?
A 2021 study found associations between widespread pain and heightened risk of dementia and stroke.
Widespread pain is a common sub-type of chronic pain: It is long-lasting pain in multiple body regions and is associated with other physical symptoms such as fatigue, concentration problems, and psychological distress.
The authors cautioned that the “relationship between pain and cognitive decline is likely to be multi-factorial”.
Scientists are still working out how to study this problem.
