New study findings have shown that constipation is associated with cognitive decline.
Suffering from chronic constipation, defined by the researchers as having a bowel movement only every three or more days, has been associated with a 73% higher risk of subjective cognitive decline, according to the study presented at a conference in Amsterdam.
“Our study provided unique evidence that examined a wide range of bowel movement frequency,” said Dr. Chaoran Ma. He is the study’s first author and assistant professor in the department of nutrition at the University of Massachusetts Amherst. “We were surprised at how robust the associations were, especially for those with very infrequent bowel movements.”
Gut health, constipation, and cognitive function in older adults
Constipation affects 16% of adults globally, especially among older individuals due to lack of exercise, fiber, and medication factors.
Chronic constipation links to inflammation and mental health issues, but questions remain about digestion and cognition.
Cognitive function refers to a person’s mental capacity for learning, thinking, reasoning, problem-solving, decision-making, remembering, and paying attention.
To investigate these questions, the researchers examined data from over 112,000 adults who participated in different studies. They collected data on participants’ bowel movement frequency from 2012 to 2013, self-assessments of cognitive function between 2014 and 2017, and details on some participants’ objectively measured cognitive function between 2014 and 2018.
Compared to individuals who had one bowel movement per day, those who were constipated had significantly worse cognition, equivalent to three years more of cognitive aging. There was also an increased risk among those who had more than two bowel movements per day, although the odds were smaller.
“The more we learn about the gut-brain axis, the more we understand that it’s crucial to ensure that (preventing or addressing cognitive decline) is a systemic approach,” said Maria C. Carrillo, chief science officer of the Alzheimer’s Association, who wasn’t part of the research. “The brain is not completely isolated from what’s happening in your blood flow.”
Gut microbes and cognitive health
The research didn’t test the causal link between bowel movements, the gut microbiome, and cognitive health. Thus, the precise causal sequence underlying this association remains uncertain.
However, bowel movement frequency and subjective cognitive function were also linked to the participants’ gut microbiomes. Among those with infrequent bowel movements and worse cognitive function, there was a depletion of good bacteria that produce butyrates, fatty acids that support the gut barrier, preventing bacteria and other microbes from entering the bloodstream.
Butyrates also significantly aid in digestive health by providing the main energy source for colon cells. These beneficial bacteria can be found in high-fiber foods, supplements, prebiotics, and full-fat dairy like butter, cheese, and milk.
On the other hand, participants with frequent bowel movements and worse cognition had more inflammation-promoting species linked to disease.
Other research presented at the same conference on Wednesday had similar findings. In one study with 140 middle-aged adults, lower levels of gut bacteria Butyricicoccus and Ruminococcus was linked to Alzheimer’s biomarkers.
Alistipes bacteria and cognitive health
In another study involving over 1,000 adults, those with poor cognition had abnormally high amounts of the bacteria Alistipes and Pseudobutyrivibrio compared to other participants. Researchers have previously linked Alistipes bacteria to anxiety, chronic fatigue syndrome, depression, and hypertension.
“It makes sense that individuals who have bowel movements much less frequently will have fewer good bacteria and more bad bacteria caused by inflammatory conditions,” Carrillo explained.
According to Dr. Ma, we need further research to identify the involved microbes and their functions.
Concerning neurological and digestive health, “good food not only feeds our brain, but it also promotes healthy bowel movements,” Carrillo added.
To prevent constipation, it is essential to consume enough fiber from vegetables, fruits, whole grains, and nuts. The US Food and Drug Administration recommends a total fiber intake of at least 25 grams per day. Staying hydrated is also important as it softens stool, making it easier to pass without straining.