Clinical Relevance: Regular laxative use may be tied to an increased risk in dementia

  • A new study hints that regular use of over-the-counter laxatives is associated with more than 50 percent increased risk of dementia.
  • The type and frequency of laxative use affected the level of risk, with osmotic laxatives carrying the greatest risk.
  • Researchers stressed that the study only found an association, not a causal relationship between laxative use and dementia.

Here’s the poop on regular laxative use for constipation: it may up the risk of dementia by more than 50 percent. 

According to the researchers from KU Alzheimer’s Disease Research Center, who published in an online issue of Neurology®, the medical journal of the American Academy of Neurology, their study does not prove that laxatives are a cause of dementia. Only that there is an association. The researchers also said they looked at frequency of use but did not explore how dosage might make a contribution.

The study reviewed over-the-counter laxative habits of more than 500,000 people listed in the UK biobank database with an average age of 57. None had dementia at the start of the study, including the 3.6 percent who reported using laxatives on a regular basis, defined as most days of the week for at least a month prior to the start of the study.

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Just over one percent of the regular laxative users developed dementia within a decade. This was more than triple the rate among the non-laxative users, the researchers found. After adjusting for factors such as age, sex, education, other illnesses and medication use, and a family history of dementia, the data suggested that people who regularly used laxatives had a 51 percent increased risk of overall dementia compared to people who did not regularly use laxatives.

Dementia risk was impacted by which type of laxative a person took, and how many times they took it. People who used a single kind of laxative had a 28 percent increased risk, compared to a 90 percent increased risk for people taking two or more kinds.

Osmotic laxatives that soften stool by drawing water to the colon carried the greatest risk. Of those who used one type of constipation aid, only those taking osmotic laxatives had a heightened dementia risk — a 64 percent increase compared to those who abstained laxatives.

“Constipation and laxative use are common among middle-aged and older adults,” said study author Feng Sha, of the Shenzhen Institute of Advanced Technology at the Chinese Academy of Sciences in Guangdong, China. “However, 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 added that patients often ignore advice from their doctors to limit use of osmotic and stimulant laxatives (which encourage muscle action in the intestinal wall.) She also noted that laxatives were not associated with an increased risk of Alzheimer’s disease, which accounts for 60 to 70 percent of all dementia cases.

While Sha stopped short of saying patients should not use laxatives to “move things along” so to speak, she said it was crucial to find ways to reduce a person’s chances of developing dementia by identifying risk factors that can be modified.

“More research is needed to further investigate the link our research found between laxatives and dementia. If our findings are confirmed, medical professionals could encourage people to treat constipation by making lifestyle changes such as drinking more water, increasing dietary fiber and adding more activity into their daily lives,” she said.