Relationship between the Japanese-style diet, gut microbiota, and dementia: a cross-sectional study

Abstract

Background Previous studies have shown associations between the gut microbiota, microbial metabolites, and cognitive decline. However, the effect of the dietary composition on such associations has not been fully investigated. Methods We performed a cross-sectional sub-analysis of data from our prospective hospital-based cohort study (the Gimlet study) to evaluate the relationships between dietary composition, cognitive decline, and the gut microbiota. All the participants of the Gimlet study had been provided with information regarding this sub-study in 2018. Patients were excluded if they were unable to provide sufficient data in the questionnaire regarding their dietary composition. We assessed their demographics, dietary composition, risk factors, cognitive function, results of brain imaging, gut microbiome, and microbial metabolites. On the basis of previous studies, a nine-component traditional Japanese diet index (JDI9), a 12-component modern JDI (JDI12), and a 12-component revised JDI (rJDI12), were defined. Higher JDI scores indicated greater conformity to the traditional Japanese diet. We then evaluated the relationships between the JDI scores, cognitive function, and the gut microbiome and microbial metabolites using multivariable logistic regression analyses. Results We analyzed data from 85 eligible patients (61% women; mean age: 74.6 ± 7.4 years; mean Mini-Mental State Examination score: 24 ± 5). Compared with participants with dementia, those without dementia were more likely to consume foods in the JDI12, including fish and shellfish (64.5% vs. 39.1%, P = 0.048), mushrooms (61.3% vs. 30.4%, P = 0.015), soybeans and soybean-derived foods (62.9% vs. 30.4%, P = 0.013), and coffee (71.0% vs. 43.5%, P = 0.024). There were non-significant trends towards lower fecal concentrations of gut microbial metabolites in participants with a more traditional Japanese diet. Participants with dementia had lower JDI9, JDI12, and rJDI12 scores than participants without dementia (dementia vs. non-dementia, median JDI9 score: 5 vs. 7, P = 0.049; JDI12: 7 vs. 8, P = 0.017; and rJDI12: 7 vs. 9, P = 0.006, respectively). Conclusions Adherence to a traditional Japanese diet was found to be inversely associated with cognitive decline and tended to be associated with lower concentrations of gut microbial metabolites. Trial registration: UMIN000031851.

Association between behavioral and psychological symptoms and cerebral small vessel disease MRI findings in memory clinic patients

“…First, we assessed the existence of BPS only through clinical interviews and medical records; hence, the quantification of BPS was not evaluated using scales such as the neuropsychiatric inventory (NPI), which has been previously associated with SVD score (Zhào et al, 2021). Second, the previous reports about the association between SVD and apathy mainly focused on hypertensive small vessel disease and thus may not be relevant to cerebrovascular diseases (Saji et al, 2021;Zhào et al, 2021). Third, although more than half of our patients met the criteria for CAA, a recent report has shown that neuropathological findings of CAA were not associated with neuropsychological symptoms (Gibson et al, 2022); however, their result might be due to the number of cases with vascular lesions in their study, as other reports clearly show that neuropsychological symptoms are common in CAA (Smith et al, 2021).…”

Evaluating the clinical relevance of the enterotypes in the Estonian microbiome cohort

“…Besides the lifestyle, the associations between enterotypes and complex diseases have gained special interest due to the potential for direct diagnostic application. Previously, enterotypes have been associated with numerous diseases such as dementia (Saji et al, 2019) and colorectal cancer (Zeller et al, 2014). It is noteworthy that in these studies the anthropometric measurements and lifestyle factors, which are common confounders in microbiome studies (Vujkovic-Cvijin et al, 2020), are often not adjusted for.…”

Gut inflammation associated with age and Alzheimer’s disease pathology

“…PPIs are associated with lower microbiome a-diversity, higher abundances of genera including Enterococcus, and lower abundances of genera including Bifidobacterium (52). Enterococcus faecalis has been shown to generate neurofibrillary epitopes in rat cortical neurons, while Bifidobacterium species are differentially abundant in AD compared with controls (24,66,67). Bifidobacterium species produce numerous potentially disease-modifying metabolites, including peptides which inhibit angiotensin converting enzyme activity and short-chain fatty acids that contribute to intestinal barrier maintenance (68,69).…”

“…Candidate activators may include microbial-derived molecules including metabolites and toxins in systemic circulation, as microglia respond to numerous damage-and microbe-associated molecular patterns arising during cellular injury or infection (29,30). Furthermore, factors including gut dysbiosis and gut bacteria derived metabolites have been linked to inflammation, preclinical cognitive decline, and AD diagnosis, but their mechanistic relationships with pathology remain ill-defined (23,24,(31)(32)(33)(34)(35). Interestingly, a nationwide population study in Taiwan (1,742 cases, 17,420 controls) found that inflammatory bowel disease (IBD) was associated with higher risk of developing AD dementia, suggesting a possible role for intestinal inflammation and permeability in AD (36).…”