Regularly using OTC laxatives may increase the risk of developing dementia by more than 50 per cent. The risk seems even higher with osmotic laxatives.

Research followed 502,229 people in the UK with an average age of 56.5 years who did not have dementia. During the mean 9.8 year follow-up, 1.3 per cent of regular laxative users and 0.4 per cent of controls developed all-cause dementia.

At baseline, 3.6 per cent of participants reported using an OTC laxative most days during the four weeks before the study. These regular laxative users were, after allowing for confounders, at a 51 and 65 per cent increased risk of all-cause and vascular dementia respectively. No significant association emerged for Alzheimer’s disease.

Overall, using one type of laxative increased dementia risk by 28 per cent compared with controls. Using only osmotic laxatives increased the risk of all-cause and vascular dementia by 64 and 97 per cent respectively. People taking at least two types of laxative increased the risk by 90 per cent. The researchers were unable to explore the relationship between laxative dose and dementia.

The study cannot confirm cause and effect, so further studies need to confirm the link and clarify the mechanism. “Constipation and laxative use are common among middle-aged and older adults,” said study author Dr Feng Sha of the Shenzhen Institute of Advanced Technology at the Chinese Academy of Sciences, Guangdong. 

“However, regular laxative use may change the microbiome of the gut, possibly affecting nerve signalling from the gut to the brain or increasing the production of intestinal toxins that may affect the brain.” (Neurology DOI: 10.1212/WNL.0000000000207081)