Laxative use may be linked to dementia risk, says study

CNN
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Researchers say they have found a possible link between regular laxative use and a person’s risk of dementia, but experts note that the research is very early and caution should be exercised.

According to the researchers, from medical institutions across China as well as Cambridge University and Harvard Medical School, Constipation affects about 20% of the general population and about 70% of people in nursing homes, and most people with constipation are treated with one of two types of over-the-counter laxatives.

The study, published Wednesday in the American Academy of Neurology’s medical journal, Neurology, suggests that a potential dementia link is strongest with osmotic laxatives, which draw water into stool to make it softer and easier to pass. . The other major type, a stimulant laxative, increases muscle contractions along the mass of the stool.

The study included around 10 years of self-reported data from 476,219 adults aged 40 to 69 in the UK. At the beginning, the study authors identified the participants’ health status and lifestyle factors, including their exposure to over-the-counter laxatives. About 3.6% of participants reported that they used a laxative most days of the week in the past four weeks.

These regular users were more likely to be women, to have less education, to have a chronic illness, and to take anticholinergic and opioid drugs regularly. “The prevalence of stroke, high blood pressure, depression, poor overall self-rated health, and intake of calcium channel blockers, statins, and steroid drugs were higher among regular users than irregular users,” the study says.

​​​​The researchers found that 2,187 participants had a diagnosis of all-cause dementia, including Alzheimer’s disease and vascular dementia, by the end of the study period.

“Regular use of laxatives was associated with a higher risk of all-cause dementia, particularly in those who used multiple types of laxatives or osmotic laxatives,” they wrote in the study.

Dementia was diagnosed in 1.3% of participants who reported regular laxative use and in 0.4% of those who did not report regular laxative use.

Dr. Richard Isaacson, a preventive neurologist at the Florida Institute of Neurodegenerative Diseases, says the findings are interesting but speculative.

“Further studies are needed to definitively impact clinical practice,” said Isaacson, who was not involved in the study.

The researchers offered one explanation for the finding, which starts with the composition of the microbiome, the trillions of microorganisms that live in the gut.

They said that laxatives have a lasting effect on the microbiome and may interfere with the production of neurotransmitters necessary for normal cognitive function. An osmotic laxative may also increase the production of intestinal toxins, they wrote.

Laxatives can also disrupt the epithelial barrier, which regulates nutrient absorption and helps deliver essential substances to the central nervous system.

Limitations of the study include that patient data were self-reported and could be misdiagnosed, and that there was limited information on potential confounders such as fiber intake and severity of constipation.

Dr. Ali Rezaie, director of the GI Motility Program at Cedars-Sinai Medical Center, said he is skeptical of the findings and that the study lacks one key component needed to make an accurate connection between regular laxative use and dementia: enough details.

“Laxatives change the microbiome, but we don’t have data to suggest that those changes that cause the laxatives are the same changes we see in the dementia study,” said Rezaie, who was not involved in the research. “That’s a big step that will take years of study to figure out.”

He says that the study period was not long enough to draw concrete evidence and that the basic data of the participants does not accurately reflect what he sees in his practice.

The study equates the number of participants who regularly used laxatives to the number who experienced constipation, but the two groups may not always overlap.

“How come the prevalence of constipation in his study was only 3%?” he asked. “This simply tells me that they didn’t pick up all the constipation patients, they only picked up patients who mentioned an over-the-counter laxative they were taking regularly. … It is very unusual to find only 3% of a population to be controversial.”

Isaacson also noted the lack of participant data, particularly related to participant diversity.

“From a health equity perspective, it’s important to say that the particular study population was 90% White,” he said. “Broader conclusions based on a more diverse population really need to be withheld.”

Isaacson and Rezaie reached the same conclusion: More research is needed, and the potential link is not strong enough to change medical practice.

“We don’t want to be telling people it’s time to stop taking laxatives to lead to dementia. That’s the wrong message,” Isaacson said.

Rezaie said he worries that his patients may worry too much about the possibility of dementia and avoid the laxatives required for certain procedures.

“This could even affect our colon cancer screening,” he said.