Risk from laxatives – researchers explain “protective effect against dementia”

Gut-brain connection: When people regularly take laxatives, it could increase their risk of dementia by up to 50 percent, a cohort study suggests. In particular, the active ingredients that have an osmotic effect and are intended to soften the stool increase the risk of dementia, possibly because they change the intestinal flora and make the intestinal barrier more permeable, as the researchers report in “Neurology”. However, this did not increase the risk of Alzheimer’s.

In Germany, around 1.6 million people suffer from Alzheimer’s, vascular dementia and
other forms
affected by mental decline in old age – and the trend is rising. Genetic factors are also possible causes
air pollution
particular
viral infections
, high blood pressure, obesity and an unhealthy lifestyle. Certain drugs and a disturbed intestinal flora are also suspected of increasing the risk of dementia.

A critical look at laxatives

Now another factor may come into play: laxatives. They are particularly widespread among older people. In Germany, around 20 percent of the general population and 70 percent of nursing home residents regularly take such so-called laxatives. To find out whether this influences the risk of dementia, Zhirong Yang from the University of Cambridge and the Chinese Academy of Sciences and his team analyzed the health data of 502,229 people recorded in the UK Biobank.

At the start of the study, the test persons were between 40 and 65 years old and were regularly examined for their state of health over an average of ten years. In addition to sociodemographic characteristics, concomitant diseases and lifestyle, questions were also asked about nutrition, medication intake and, in particular, the use of laxatives. Regular laxative use was considered to be intake on most days of the week.

Higher risk of dementia but not Alzheimer’s

The result: Of the test subjects who regularly took laxatives, around 1.3 percent developed dementia over the course of almost ten years. Among the participants who did not use laxatives, it was only 0.4 percent, as determined by Yang and his team. Statistically, the comparison, taking all other risk factors into account, showed an increased risk of dementia of 50 percent with regular use of laxatives.

More detailed analyzes showed that the laxatives primarily increased the risk of dementia in general and of vascular dementia, but not of Alzheimer’s. This effect was also particularly strong in patients who had previously taken various types of laxatives or osmotically effective laxatives. These drugs draw water into the intestines, thinning the stool.

Disturbance of intestinal flora and intestinal barrier

But how can a laxative affect the brain? One possible factor is the intestinal flora: Previous studies have already shown that osmotically effective laxatives change the microbiome of the intestine. This in turn can change the production of messenger substances in the gut, which then also affect the brain via the gut-brain axis. In addition, laxatives can also weaken the intestinal barrier and thus facilitate the passage of toxins and inflammatory messengers from the intestine into the nervous system. This can also promote dementia.

The current study cannot yet prove these biological connections between laxatives and dementia. For this, more targeted clinical studies would first have to be carried out. “Nevertheless, given the results, we advise caution when using laxatives, especially given the fact that dementia is on the increase,” comments Peter Berlit, Secretary General of the German Neurological Society.

Healthy eating instead of laxatives

According to the expert, a healthy diet could protect against dementia in two ways: it makes laxatives superfluous and has a preventive effect against cognitive decline. A high-fiber diet with plenty of fruit, vegetables and whole grain products and, above all, sufficient liquid in the form of water or unsweetened tea is recommended.

“Such a change in diet may have a double protective effect against dementia,” explains Berlit. “On the one hand, laxatives, which have a potentially damaging effect on brain health, can be avoided in many cases, on the other hand, a healthy diet per se is an important pillar of dementia prevention. In order to maintain mental function into old age, it is definitely worth changing your diet.” (Neurology, 2023; doi: 10.1212/WNL.0000000000207081)

Source: German Society for Neurology eV

This article was written by Nadja Podbregar