Constipation may be a marker of dementia risk

By Amy Norton HealthDay Reporter

WEDNESDAY, July 19, 2023 (HealthDay News) — Chronic constipation may not only be an indicator of gut health, but also a potential warning sign of declining thinking, according to a preliminary study.

The researchers found that among more than 110,000 middle-aged and older American adults, those who were chronically constipated – less than three bowel movements per week – also showed signs of an “older” brain.

Compared to their regular counterparts, they generally performed worse on memory and thinking tests, which equates to three extra years of aging. And they were 73% more likely to say their cognitive abilities were declining.

The results – presented Wednesday at a meeting of the Alzheimer’s Association in Amsterdam and online – are considered preliminary. And they don’t prove that constipation, by itself, somehow causes the aging brain to deteriorate more rapidly.

But experts said the findings add to the evidence linking gut health to brain health.

One possibility, the researchers theorize, is that constipation and cognition are linked via the gut microbiome. It is the wide range of bacteria that naturally live in the intestines and play an important role in many bodily functions.

An explosion of research in recent years has focused on links between the gut microbiome and various diseases, including degenerative brain diseases like Alzheimer’s disease. The question is whether certain gut microbiome profiles — an abundance of particular “bad” bacteria or a shortage of certain “good” ones — might contribute to these health issues.

A recent studyfor example, found that people with early markers of Alzheimer’s disease – an abnormal buildup of proteins in the brain – also had gut microbiomes that looked different from those of other older people.

In theory, constipation could be a symptom of a gut microbiome associated with lower cognition. But that remains to be proven.

“It’s unclear at this point whether the constipation itself or the underlying cause of the constipation – whether gut microbiome disruptions or a change in diet – is at the root of the problem. origin of this association,” said Claire SexonSenior Director of Scientific Programs and Outreach for the Alzheimer’s Association.

Sexton, who was not involved in the study, said if people have chronic constipation, they can talk to their doctor about how to deal with it.

Dr. Dong Wangthe study’s lead researcher, made similar remarks.

“These findings underscore the importance for clinicians to discuss gut health, especially constipation, with their older patients,” said Wang, of Brigham and Women’s Hospital and Harvard Medical School.

He added that people can prevent constipation and improve their gut health by eating plenty of fiber-rich foods like vegetables, fruits, whole grains and beans, and exercising regularly.

Other research has linked these same lifestyle habits to a lower risk of age-related cognitive decline and dementia.

Wang’s team based their findings on data from three large studies that followed more than 100,000 American healthcare professionals for decades. In 2012-2013, participants reported on their bowel habits, and between 2014 and 2017 they self-assessed their cognitive function.

A subset underwent objective tests of memory and thinking skills between 2014 and 2018.

On average, the researchers found that these objective scores were lower in people who reported chronic constipation — not having a bowel movement more often than every three days — compared with people who were like clockwork (a stool per day).

Similarly, people with constipation gave lower ratings to their subjective cognitive abilities.

Next, the researchers looked at the question of microbes. They found that people with constipation and cognitive impairment tended to have relatively few gut bacteria that produce butyrate, an important fatty acid that helps control inflammation. Gut bacteria produce butyrate when they break down fiber.

Two other studies presented at the conference confirm the gut-brain connection.

Researchers at UT Health San Antonio found that middle-aged and older adults with “poor cognition” tended to have low levels of certain good gut bacteria. Meanwhile, older people with abnormal protein buildup in the brain (but no symptoms of dementia) also showed depleted levels of certain good bacteria.

Although the results are intriguing, much more research is needed, Sexton said.

Researchers are a long way from proving that modifying gut bacteria — through diet, probiotics, or other means — can help keep the aging brain fit.

The Alzheimer’s Association is conducting a clinical trial testing the effects of a healthy diet (high in plant foods and fiber), exercise, and other lifestyle measures to slow cognitive decline in older adults.

Sexton said this will include a deeper dive into the question of the gut brain — looking at whether lifestyle changes alter people’s gut bacteria and whether those changes correlate with their cognitive health.

Research presented at medical meetings is generally considered preliminary until it is published in a peer-reviewed journal.

The Alzheimer’s Association has advice on support brain health.

SOURCES: Claire Sexton, DPhil, senior director, science programs and outreach, Alzheimer’s Association, Chicago; Dong Wang, ScD, MD, assistant professor, medicine, Brigham and Women’s Hospital, Boston; presentation, Alzheimer’s Association International Conference, Amsterdam and online, July 19, 2023

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