Bowel movement frequency, gut microbiome linked to cognitive function

Key takeaways:

• Study assessed more than 112,000 individuals.
• Constipated participants had significantly worse cognition, equal to 3 years of aging, compared with those with once-daily bowel movements.

Chronic constipation was associated with worse cognitive function, equal to 3 years of additional aging, according to research presented at the Alzheimer’s Association International Conference.

“Interventions for preventing constipation and improving gut health include adopting healthy diets enriched with foods such as fruits, vegetables and whole grains, taking fiber supplementation, drinking plenty of water every day and having regular physical activity,” senior study investigator Dong Wang, MD, ScD, assistant professor at Harvard Medical School, Brigham and Women’s Hospital and Harvard T.H. Chan School of Public Health, said in a related release.

Wang, along with presenter Chaoran Ma, MD, PhD, assistant professor of nutrition at University of Massachusetts Amherst School of Public Health & Health Sciences, and colleagues sought to examine associations between frequency of bowel movements, the gut microbiome, cognitive function and dementia risk.

They assessed 112,753 adults from the Nurses’ Health Study (NHS), Nurses’ Health Study II (NHSII) and Health Professionals Follow-Up Study (HPFS) and also evaluated the role of the gut microbiome in a sub-cohort of 515 NHSII and HPFS participants.

Researchers collected data on bowel movement frequency in 2012 and 2013 and subjective cognitive function from 2014 to 2017 in all participants. They also determined objective cognitive function via neuropsychological testing from 2014 to 2018 in 12,696 NHSII participants.

According to results, participants with bowel movement frequency of every 3 days or less experienced significantly worse cognition, equivalent to 3 years (95% CI, 1.2-4.7) of cognitive aging, compared with those who had once-daily bowel movements.

Researchers also reported that both constipation and bowel movement frequencies of at least two times per day were associated with subjective cognitive decline (OR = 1.73; 95% CI, 1.6-1.86 and OR = 1.37; 95% CI, 1.33-1.44, respectively) compared with once-daily bowel movements.

Further, data showed that bowel movement frequency and subjective cognition were significantly associated with overall variation of the gut microbiome. Specifically, butyrate producers were diminished in participants with less frequent bowel movements and poorer cognitive function, while an increase in proinflammatory species was linked with more frequent bowel movement frequency ( 2/day) and worse cognition.

“These results stress the importance of clinicians discussing gut health, especially constipation, with their older patients,” Wang said in the release.

Reference:

• Constipation associated with worse cognition, more cognitive aging. https://aaic.alz.org/releases_2023/constipation-gut-health-alzheimers-dementia-risk.asp. Published July 19, 2023. Accessed July 19, 2023.