• Posted February 23, 2023

Could High Laxative Usage Raise the Odds for Dementia?

Taking laxatives regularly to ease constipation may up your chances of developing dementia down the road, a new study suggests.

This risk is even higher among folks who use multiple types of laxatives or osmotic laxatives, which work by drawing water into stool.

Previous research has linked other over-the-counter drugs, including non-prescription sleep aids and allergy medications to dementia, but this is the first time that laxative use has been implicated.

"Regular use of laxatives, even without short-term severe adverse events, may have the potential long-term risk of dementia, especially when it comes to osmotic laxatives and combination use of two or more types of laxatives,"said study author Feng Sha, an associate professor at the Shenzhen Institute of Advanced Technology at the Chinese Academy of Sciences in China.

Still, it's not time to hit the panic button just yet.

"This finding requires confirmation by further studies before more actions should be taken," Sha said.

What's more, the absolute risk was still small and the new study wasn't designed to say exactly how laxative use may raise the risk for dementia, although researchers do have their theories.

"Regular laxative use may change the microbiome of the gut, possibly affecting nerve signaling from the gut to the brain or increasing the production of intestinal toxins that may affect the brain,"Sha said. Laxatives may also disrupt the gut-brain axis, allowing some microorganisms to reach the brain, he added.

For the study, the researchers looked at laxative use in more than half a million people participating in the ongoing U.K. Biobank research project. Folks were at an average age of 57, and no one had dementia at the start of the study. Of these, 3.6% reported using over-the-counter laxatives most days of the week for the last month.

During 10 years of follow-up, 1.3% of people who regularly used laxatives developed dementia. In contrast, just 0.4% of people who didn't take laxatives on a regular basis developed dementia, the study showed.

After researchers controlled for other factors known to increase risk for dementia, such as family history, they found that people who regularly used laxatives had a 51% increased risk of dementia compared to people who did not regularly use laxatives.

The more types of laxatives used, the higher the dementia risk, the study showed.

Folks using one type of laxative had a 28% increased risk, and those who took two or more types of laxatives had a 90% increased risk for dementia. Researchers did not have dosage information on laxatives.

Among people using only one laxative type, only osmotic laxatives were linked to dementia risk. Osmotic laxatives attract water to the colon to soften stool. Other types of laxatives are bulk-forming, stool-softening or stimulating.

Regular use of laxatives is not recommended, Sha said. "Constipation can be mitigated most of the time by lifestyle changes, such as increasing fluid intake, dietary fiber and activity levels, which may also benefit brain health," he noted.

Going forward, the researchers hope to look more closely at each laxative type.

"We will also try to identify potential contributory factors or specific mechanisms that may be responsible for the observed associations in our study,"Sha said. The team is also investigating how laxative use may affect other chronic diseases, such as stroke, depression and Parkinson's disease.

The study was published Feb. 23 in the journal Neurology.

Yuko Hara is director of aging and Alzheimer's prevention at the Alzheimer's Drug Discovery Foundation in New York City. She said this is the first time she has seen research linking regular laxative use to dementia.

There are some direct and indirect ways that laxative use could affect thinking and memory, Hara said.

"Laxatives could be harmful to the brain, but it could also be that people who take laxatives for constipation don't eat enough fruit or vegetables,"she said. Eating a healthy diet rich in fruits and vegetables is good for the heart and the brain, she noted.

"Laxatives may also flush out some of the good microbes from the gut, disrupting the balance of good and bad bacteria,"Hara added.

Treating constipation starts with getting more fiber in your diet through fruits and vegetables or fiber supplements, said Dr. Aditya Sreenivasan, a gastroenterologist at Lenox Hill Hospital in New York City.

"You also need adequate water intake and exercise because when you don't move, your bowels don't move,"he said.

"Try these three things to see if you can get off laxatives," Sreenivasan said. If they don't do the trick, talk to your doctor to see what else you can do to become more regular.

More information

The American College of Gastroenterology offers more on how to treat constipation.

SOURCES: Feng Sha, PhD, associate professor, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Yuko Hara, PhD, director, aging and Alzheimer's prevention, Alzheimer's Drug Discovery Foundation, New York City; Aditya Sreenivasan, MD, gastroenterologist, Lenox Hill Hospital, New York City; Neurology, Feb. 22, 2023, online