Study Links Constipation to Cognitive Decline

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There is a surprising new potential contributor to cognitive decline: constipation, according to a new, first-of-its-kind study.

“When one system is malfunctioning, it impacts other systems,” Heather Snyder, who holds a doctorate in molecular biology and is the Alzheimer’s Association vice president of medical and scientific relations, said in a statement, noting the interconnected nature of the body’s systems. “When that dysfunction isn’t addressed, it can create a waterfall of consequences for the rest of the body.”

While the study has not been published yet, the results were recently presented at the Alzheimer’s Association’s International Conference in the Netherlands and online. Still, the findings offer insight into the intricate relationship between gut and brain well-being.

Prevalence and Causes of Constipation

Constipation is a prevalent gastrointestinal issue, prompting 2.5 million yearly doctor visits. Chronic constipation is defined as having a bowel movement every three or more days. It’s been associated with long-term health issues, including inflammation, hormonal imbalances, and anxiety or depression.

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According to a 2012 survey, one-third of those older than 60 and about 16 percent of the population are living with constipation.

Causes of Constipation. The Epoch Times

The Gut-Brain Connection

To examine whether constipation could impact cognitive health, researchers analyzed data from three ongoing cohort studies: the Nurses’ Health Study, the Nurses’ Health Study II, and the Health Professionals Follow-up Study. Combined, these studies included over 110,000 participants.

Between 2012 and 2013, participants reported the frequency of their bowel movements. Then from 2014 to 2018, researchers completed assessments of the cognitive function of nearly 13,000 participants, both subjectively and through objective testing.

The researchers found evidence linking less frequent bowel movements to worse cognitive function, which includes mental processes such as receiving, processing, storing, and acting on information.

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Compared to people with daily bowel movements, constipated people showed cognitive decline equivalent to aging an extra three or more years. Constipation was also associated with a 73 percent increased risk of subjective cognitive issues.

But it wasn’t just infrequent bowel movements that were associated with cognitive issues. There was also a slightly higher risk of cognitive decline among those who had bowel movements more than twice a day.

One hypothesis is that gut bacteria may play a role in the connection between constipation and brain health. Participants with lower levels of microbes—that is, lower levels of compounds that support the gut barrier, and lower levels of bacteria that help fiber digestion—tended to be more constipated and have poorer cognition.

More Research Supports Gut Health and Brain Function Link

Two other studies presented at the Alzheimer’s conference added further clues about the interplay between gut health and cognitive abilities as people age.

Alzheimer’s Disease

In one of these studies, a mouse model of Alzheimer’s was used to illustrate a link between the accumulation of beta-amyloid and tau, prominent markers of Alzheimer’s, and the presence of specific gut bacteria.

The results revealed that increased levels of these proteins, identified through brain scans, were associated with reduced quantities of gut bacteria known as Butyricicoccus and Ruminococcus, which may have neuroprotective effects, but elevated levels of the bacteria Cytophaga and Alistipes.

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“We believe that the reduction of certain identified bacteria may increase gut permeability and the transport of toxic metabolites in the brain, thus increasing amyloid-beta and tau deposition," one of the study authors, Yannick Wadop, a postdoctoral fellow at the Glenn Biggs Institute for Alzheimer’s, said in a press statement.

Poor Cognition

The second study examined the gut microbiome profiles of more than 1,000 middle-aged and elderly individuals participating in the Framingham Heart Study, a comprehensive, multigenerational investigation aimed at identifying shared elements contributing to cardiovascular disease.

Participants who scored lower on cognitive testing tended to have fewer bacteria like Clostridium and Ruminococcus and higher amounts of Alistipes and Pseudobutyrivibrio than those with better cognition.

The study cannot prove that differences in gut bacteria directly cause cognitive decline.

“Further research is needed to better understand the possible neuroprotective effects of some of these bacteria,” Jazmyn Muhammad, a research associate at the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases and one of the authors, said in a statement. “In the future, it may be possible to manipulate the abundance of these bacteria through diet and pre/probiotics to preserve brain health and cognitive function,” she added.

Can Preventing Constipation Reduce Our Risk of Cognitive Decline?

Experts not affiliated with the research say that more work is needed to prove a correlation.

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While the findings suggest an association between chronic constipation and cognitive decline, “association does not imply causation," Dr. Nikhil Palekar, director of the Stony Brook Center of Excellence for Alzheimer’s Disease and director of the Stony Brook Alzheimer’s Disease Clinical Trials Program, told The Epoch Times.

Nonetheless, Dr. Palekar underscored the significance of the recent findings, noting their potential to drive future investigations into the interplay between digestive symptoms and cognitive function. He recommended that people with infrequent bowel movements address chronic constipation through open communication about the symptoms with their primary care physicians, facilitating appropriate treatment.

“Cognitive decline is often multifactorial,” Dr. Palekar said. Considering the study’s results, it would be “reasonable” to anticipate a potential reduction in the risk of cognitive decline through the treatment or prevention of constipation, he added.

Dr. Palekar highlighted the importance of preventing chronic constipation, possibly even surpassing the treatment of existing constipation. He also recommended adopting common-sense lifestyle habits, such as enhancing dietary fiber intake, staying adequately hydrated, and maintaining a consistent exercise routine.

As per guidelines, aiming for a daily intake of 25 to 30 grams of fiber is advised. Incorporating a diet abundant in plant-based foods provides a simple means of meeting these fiber requirements. For instance, a mere ounce of chia seeds offers 10 grams of fiber, while a cup of black beans supplies 15 grams. Other foods rich in fiber include lentils, green peas, and berries.