A new study associates experiencing less frequent bowel movements with poorer cognitive function.
The gut microbiome, the community of good and bad microorganisms living in the digestive tract, plays an important role in overall human health and may contribute to several chronic conditions. Previous studies have associated certain gut bacteria with neurodegenerative illnesses, such as dementia and Parkinson’s disease.
"Still, there are a lot of unanswered questions about the connection between the health of our digestive system and our long-term cognitive function," says Heather M. Snyder, Ph.D., Alzheimer’s Association vice president of medical and scientific relations.
The new study presented at the Alzheimer’s Association International Conference in Amsterdam examined the relationship between cognitive function and chronic constipation, defined as having bowel movements every three days or less.
The study included data from 110,000 health professionals: their bowel movement frequency in 2012 to 2013 and their self-assessments of cognitive function from 2014 to 2017. Over 12,696 participants had their cognitive function measured between 2014 and 2018.
The researchers found that less frequent bowel movements were associated with poorer cognitive function. Constipated participants had significantly worse cognition, equivalent to three years more of chronological cognitive aging, and were 73% more likely to experience subjective cognitive decline compared to the participants with bowel movements once daily.
The risk of cognitive decline was also slightly higher in those who had bowel movements more than twice a day.
Study participants with fewer bacteria in the gut that can produce butyrate, a beneficial fatty acid, and fewer bacteria responsible for digesting dietary fibers had both less frequent bowel movements and worse cognitive function.
"These results stress the importance of clinicians discussing gut health, especially constipation, with their older patients," says senior investigator of this study, Dong Wang, M.D., Sc.D., an assistant professor at Harvard Medical School, Brigham and Women’s Hospital and Harvard T.H. Chan School of Public Health. "Interventions for preventing constipation and improving gut health include adopting healthy diets enriched with high-fiber and high-polyphenol foods such as fruits, vegetables, and whole grains; taking fiber supplementation; drinking plenty of water every day; and having regular physical activity."
About 16% of the world’s population experience chronic constipation. While the condition rarely causes complications, in some patients, it may lead to hemorrhoids, dry, hard stools collecting in the rectum, and bowel incontinence.
There are many causes of chronic constipation, including:
- Not eating enough fiber or/and not drinking enough liquids
- Low levels of physical activity
- Conditions affecting the brain and spine, metabolism, hormones
- Daily routine changes like pregnancy, traveling, changes in diet or medicines
- Certain medicines, including the ones that contain aluminum and calcium, iron supplements
Although further research is necessary, the findings suggest that following a healthy diet and taking care of the gut may play a role in preventing dementia.
- Alzheimer’s Association. Constipation Associated with Cognitive Aging and Decline.
- Nagoya University Graduate School of Medicine. Researchers identify three intestinal bacteria found in dementia with Lewy bodies.
- National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of Constipation.