An active toilet habit may ward off mild cognitive impairment

Having an active bowel movement and a high fruit consumption appears to be protective against mild cognitive impairment (MCI) among elderly adults, according to a new Singapore study.

“In the present study, we aimed to dissect the associations of bowel movement frequencies and dietary habits with clinical-diagnosed MCI in a population-based cross-sectional study,” the Diet and Healthy Ageing study in Singapore, the researchers said.

Of the 751 enrolled participants, 119 elderly adults (mean age, 68.9±6.9 years) were identified to have MCI, resulting in a prevalence rate of 15.9 percent; the remaining were designated as cognitively healthy controls and were, on average, significantly younger than those with MCI (mean age, 67.4±5.3 years; p=0.007). MCI participants also had a significantly heavier comorbidity burden. [Aging 2020;doi:10.18632/aging.103674]

In addition, MCI seniors more commonly complained about infrequent bowel movement (≤3 days per week) than their non-MCI comparators (26.7 percent vs 17.2 percent; p=0.013).

The researchers also observed important differences in dietary habits. For instance, univariate analysis revealed that MCI participants were more likely to eat fruits infrequently (≤3 days per week) than their cognitively healthy comparators (35.3 percent vs 19.0 percent; p<0.001). The same was true for meat (p=0.014) and egg (p=0.04) intake. Consumption of dairy products, vegetables, and seafoods, among others, did not differ between groups.

An association between diet and bowel movement was found. Elderly adults with an active bowel movement were more likely to have a high-frequency fruit consumption (≥4 days per week; p=0.033).

Multiple logistic regression analysis confirmed the interaction between bowel movement and MCI. Having an active bowel movement (≥4 days per week) reduced the risk of developing MCI by more than 40 percent (adjusted odds ratio [OR], 0.582, 95 percent confidence interval [CI], 0.360–0.941; p=0.027). Active fruit consumption had a similar effect (adjusted OR, 0.516, 95 percent CI, 0.330–0.808; p=0.004).

Other important correlates of MCI risk were years of schooling (adjusted OR, 0.906, 95 percent CI, 0.861–0.954; p<0.001) and comorbidities, such as hypertension (adjusted OR, 1.770, 95 percent CI, 1.159–2.705; p=0.008) and stroke (adjusted OR, 2.514, 95 percent CI, 1.065–5.936; p=0.035).

A Bayesian network model was then constructed to identify potentially causal associations. The model yielded five causal paths. Bowel movement and stroke were directly connected to MCI occurrence, while years of schooling had an indirect effect through fruit consumption. Hypertension also emerged as an indirect factor, linked to MCI through either stroke or cataracts/glaucoma.

“Gut-brain axis dysfunction has been hypothesized to be an essential factor in neurological diseases,” the researchers said. “However, there is a scarcity of solid epidemiological evidence associating bowel movement (or constipation) with cognitive impairments.”

The present study adds to the existing literature in this regard, identifying diet and bowel movement as important contributors to MCI risk. “[I]t would be advisable to decrease risks of MCI by adopting a healthy fruit consumption habit, improving bowel movement and by well management of stroke and hypertension,” the researchers added.