Clinical study presented at AAIC finds a link between chronic constipation and cognitive decline in older adults

19/07/2023

Constipation is more frequent in older adults, due to age-related factors such as lack of physical exercise, diets that may be low in fibre, and medicines for chronic conditions that can cause constipation. New research presented at AAIC last week indicates that chronic constipation may impact cognitive function as we age, revealing a potential link between the gut microbiome and brain health. To study the relationship between constipation and cognitive decline in older adults, Dr. Chaoran Ma of the University of Masssachusetts studied data and samples from over 110,000 participants in three prospective, US-based cohort studies: the Nurses’ Health Study, the Nurses’ Health Study II, and the Health Professionals’ Follow-up study. Participants in these cohorts undergo regular assessments of health and lifestyle factors, designed to understand risk factors for major chronic diseases.

Dr. Ma’s team collected information on bowel movement frequency in 2012-2013, as well as self-assessments of cognitive function in the ensuing 4 years; cognitive tests were also conducted between 2014 and 2018, in a subgroup of 12,696 participants. The gut microbiota of 515 men and women was profiled in fecal samples using a new technique called shotgun metagenomic analysis, which is able to identify the types of bacteria present in the gut. Data analyses revealed that participants with chronic constipation (defined as bowel movements every 3+ days) were 73% more likely to report subjective cognitive decline. They also found a link between chronic constipation and poorer cognitive function based on objective tests, equivalent to an estimated 3 years of chronological cognitive aging compared to participants with regular, daily bowel movements.

The researchers identified differences in gut microbiome composition in participants with chronic constipation, suggesting that those with fewer bacteria responsible for producing butyrate or digesting dietary fibre were more likely to experience constipation and worsening cognitive function. Together, these results highlight the importance of addressing constipation as we age, by maintaining a balanced, fibre-rich diet, drinking plenty of water, and exercising. Read the AAIC press release: https://aaic.alz.org/releases_2023/constipation-gut-health-alzheimers-dementia-risk.asp