March 8, 2023
Regular use of laxatives, commonly taken to relieve constipation, is associated with an increased risk for dementia, according to a new report. The study found that people who took laxatives most days of the week increased their risk of Alzheimer’s disease and other forms of dementia by more than 50 percent. Taking multiple kinds of laxatives was especially problematic, increasing the risk of dementia even further.
Constipation affects some 20 percent of the general population, 40 percent of older adults, and up to 70 percent of those living in nursing homes. Many people are embarrassed by the problem and don’t talk about it with their doctors. Instead, many turn to over-the-counter laxatives, sold in pharmacies and drug stores, for relief. Regular laxative use may become a habit, as people think they must continue taking them to stay “regular,” even though those medications are not intended to be taken on a long-term, daily basis.
For the study, researchers tracked 502,229 men and women in their 40s, 50s and 60s who were part of UK Biobank, a large medical database of people living in Britain. Their average age was 57. None had a history of Alzheimer’s disease or other serious memory problems at the start of the study. More than 18,000, or 3.6 percent, of them reported using laxatives on a daily or almost-daily basis.
Over the next 10 years, more than 2,000 of the study participants developed Alzheimer’s disease or other forms of dementia, including more than 200 who were regular laxative users. After adjusting for factors such as age, sex, education, other illnesses and medication use, and a family history of dementia, the researchers found that people who regularly used laxatives were 51 percent more likely to develop dementia than those who infrequently or never used laxatives.
People who took osmotic laxatives, which draw water into the colon to soften stool, were at particularly high risk of dementia, the researchers found. (Examples of osmotic laxatives include Miralax and Milk of Magnesia.) So were those who used multiple kinds of laxatives, such as bulk-forming laxatives, which add bulk to the stool; stool softeners; or stimulant laxatives, which speed up the movement of stool through the colon. The findings were published in Neurology, the medical journal of the American Academy of Neurology.
The study shows only an association between regular laxative use and the onset of dementia, and cannot prove cause and effect. But study author Feng Sha, of the Shenzhen Institute of Advanced Technology at the Chinese Academy of Sciences in Guangdong, China, said that laxatives may alter the composition of the gut microbiome, the trillions of bacteria, viruses and fungi that inhabit the intestinal tract. Scientists increasingly recognize that a healthy balance of microbes in the gut is crucial for good health, not just for digestive health but for health throughout the body, including the brain.
“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,” Dr. Sha said. “Our research found regular use of over-the-counter laxatives was associated with a higher risk of dementia, particularly in people who used multiple laxative types or osmotic laxatives.”
Dr. Sha noted that osmotic and stimulant laxatives, in particular, are not recommended for persistent daily use, yet many people use them regularly.
“More research is needed to further investigate the link our research found between laxatives and dementia,” Dr. Sha added. “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.”
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Zhirong Yang, Chang Wei, Xiaojuan Li, et al: “Association Between Regular Laxative Use and Incident Dementia in UK Biobank Participants.” Neurology, February 22, 2023