People Who Regularly Use Laxatives May Have an Increased Risk of Dementia, Study Shows

People who regularly use laxatives to help treat constipation may have an increased risk of developing dementia, new research shows.

The findings come from a February study published in the journal Neurology, which identified a 51% increased risk of overall dementia among people who regularly used laxatives, compared to those who didn’t use the over-the-counter medication. Using multiple types of laxatives, or osmotic laxatives, further increased the risk of both all-cause dementia and vascular dementia.

“Constipation and laxative use are common among middle-aged and older adults,” study author Feng Sha, PhD, associate professor at the Shenzhen Institute of Advanced Technology at the Chinese Academy of Sciences in Guangdong, China, said in a news release.

Though certain laxatives, like stimulant and osmotic laxatives, aren’t recommended for regular use, they are still widely used on a habitual basis.

“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 in the news release. “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.”

It’s important to note that the research only shows a potential association—by no means does it suggest that regular laxative use will cause dementia. However, the findings not only introduce new potential contributors to dementia that scientists can further explore, but they may also encourage people to consider other alternatives to regular laxative use.

Laxative Use Linked to Increased Dementia Risk

According to Sha, who studies different behaviors and exposure that may raise or lower a person’s risk of dementia, he got the idea to research laxative use after hearing about how the medication is used in some older adults living in assisted-living facilities.

He revealed that most residents take several kinds of medications—including laxatives—and some of the more heavily-medicated patients developed dementia sooner than others. “I immediately realized laxatives may be linked to dementia through the gut-brain axis,” Sha told Health.

For the new study, Sha and his team of researchers used the UK Biobank database to collect medical information on 502,229 adults between the ages of 40 and 69. About 3.6% (18,235 adults) reported using over-the-counter laxatives on a regular basis. (Regular use was defined as using laxatives most days of the week the month before the study began.)

Of those who routinely used laxatives, 218 (1.3%) developed dementia, compared to just 0.4% of people who did not regularly use laxatives. Ultimately, regular laxative use appeared to increase a person’s risk for dementia by 51%.

“This study is quite interesting in that it has an extremely large population that was sampled,” said Theodore Stathos, MD, a gastroenterologist and medical director at Rocky Mountain Pediatric Gastroenterology, who was not a part of the research. “This would imply that laxatives do increase the general risk ratio for developing dementia in adults that are chronically using laxatives.”

The number of laxatives used, along with the type of laxative, further impacted dementia risk. People who used two or more different kinds of laxatives had a 90% increased risk of developing dementia—that’s compared to a 28% increased risk among people taking just one type.

People who regularly used osmotic laxatives—or medications that pull water from the rest of your body to soften stool—also had a 64% greater chance of developing dementia than those who did not use laxatives on a regular basis.

“Many constipation patients may misuse laxatives because they tend to self-treat with the OTC medications,” Dr. Sha said. “Therefore, pharmacists and clinicians should be well-placed in providing instructions for patients regarding the use of OTC medications for treating constipation.”

How Might Laxatives Increase Dementia Risk?

The study did not go into detail on how laxatives could increase dementia risk, but Dr. Sha said there are few possible scenarios that involve the gut microbiome.

Laxatives could affect cognition by messing with the balance between “good” and “bad” bacteria living in the gut microbiome. Previous research has shown evidence of certain gut microbes influencing the cognitive function of middle-aged adults. In this scenario, Dr. Sha said changes to gut microbiome composition may slow down the production of neurotransmitters important for normal cognitive function.

Laxatives may also potentially wear down the gut barrier. A weakened gut barrier could allow some “bad” microbes to escape, and create neurotoxic products that could infiltrate the bloodstream. One possible metabolite created from gut microbes is trimethylamine N-oxide (TMAO). If large amounts of TMAO enter the bloodstream, Dr. Sha theorized it could lead to platelet hyperactivity, blood clotting, vascular inflammation, and atherosclerosis—all contributors to stroke and vascular dementia.

Dr. Stathos offered an alternative explanation: He said the overuse of laxatives could cause permanent changes to the colon and electrolyte imbalances. Having electrolyte imbalances, such as low sodium levels, can affect a person’s mental state and cause mild cognitive impairment.

Does This Mean You Should Stop Using Laxatives?

The study identified an association between regular laxative use and all-cause dementia and vascular dementia, but it did not find any link between laxatives and Alzheimer's dementia, the most common type of dementia. An estimated 1 in 5 women and 1 in 10 men over the age of 45 will go on to develop Alzheimer’s dementia, regardless of laxative use.

According to Clifford Segil, DO, a neurologist at Providence Saint John’s Health Center who was not affiliated with the study, there were a few limitations that people should take into account when interpreting the results. It’s unclear, for example, whether it’s the laxatives causing dementia, or if it’s the dementia causing constipation and the need for laxatives. If someone has dementia, Dr. Segil said, they can forget to eat properly or drink enough fluids—all of which can lead to constipation.

And though the researchers collected medical information from a public database, they relied on self-reported questionnaires to understand laxative use in adults with and without dementia. “Patients with memory loss or dementia are unreliable historians,” Dr. Segil said.

People with dementia—specifically those with vascular dementia—also tend to have other medical issues that may affect how food is digested in and passed through the body. Diabetes, for example—which can also heighten the risk of dementia—may slow down or stop food from moving through the gastrointestinal tract, which can then slow down bowel movements.

Because the new research focused on laxative use in middle-aged adults, Dr. Stathos said that it’s unclear whether using laxatives during other ages would affect dementia diagnoses. The findings may also not be representative of a global population, since the information from the study was taken from people living in the U.K.

Ultimately, everyone’s situation is different, said Heather Snyder, PhD, vice president of medical and scientific relations at the Alzheimer’s Association. She advised patients who take laxatives to speak to a healthcare provider about the risks and benefits of laxative use, along with how often you tend to rely on medication for constipation.

If your provider suspects you’re over-using laxatives, they may offer alternative methods for constipation relief, such as increasing dietary fiber and drinking more water.

Ways to Protect Your Cognitive Health

While you can’t change certain risk factors—age, genetics, and family history of dementia—there are ways to lower your risk for cognitive decline. “Addressing modifiable risk factors might prevent or delay up to 40% of dementia cases worldwide,” Dr. Snyder told Health.

The National Institute on Aging suggests following a healthy lifestyle to address risk factors associated with Alzheimer's and related dementias. That can look like:

• Controlling high blood pressure
• Managing blood sugar
• Maintaining a healthy weight
• Eating a healthy diet
• Keeping physically and mentally active
• Staying connected with family and friends
• Treating hearing problems
• Getting adequate sleep
• Preventing head injuries
• Drinking less alcohol
• Quitting tobacco

Though experts can’t say for certain that these changes will protect against dementia, it’s safe to say that they’re all healthy habits that can support overall wellbeing.

As for laxative use, Dr. Segil recommends zeroing in on your eating habits and how those can lead to other regular activities. “The study is a great way to focus attention on how eating affects your health and how to choose foods that would not get you constipated,” Dr. Segil said