Cilostazol May Decrease Plasma Inflammatory Biomarkers in Patients with Recent Small Subcortical Infarcts: A Pilot Study

Relationship Between Plasma Lipopolysaccharides, Gut Microbiota, and Dementia: A Cross-Sectional Study

BACKGROUND

Previous studies have demonstrated associations between gut microbiota, microbial metabolites, and cognitive decline. However, relationships between these factors and lipopolysaccharides (LPS; molecules of the outer membrane of gram-negative bacteria) remain controversial.

OBJECTIVE

To evaluate associations between plasma LPS, gut microbiota, and cognitive function.

METHODS

We performed a cross-sectional sub-analysis of data of 127 participants (women: 58%, mean age: 76 years) from our prospective cohort study regarding the relationship between gut microbiota and cognitive function. We enrolled patients who visited our memory clinic and assessed demographics, dementia-related risk factors, cognitive function, brain imaging, gut microbiomes, and microbial metabolites. We evaluated relationships between cognitive decline and plasma LPS using multivariable logistic regression analyses.

RESULTS

Plasma LPS concentration increased with increasing degree of cognitive decline and total cerebral small vessel disease (SVD) score (Kruskal-Wallis test; p = 0.016 and 0.007, respectively). Participants with high plasma LPS concentrations tended to have lower concentrations of gut microbial metabolites, such as lactic acid and acetic acid, and were less likely to consume fish and shellfish (44.7% versus 69.6%, p = 0.027) than those with low plasma LPS concentrations. Multivariable analyses revealed that plasma LPS concentration was independently associated with the presence of mild cognitive impairment in participants without dementia (odds ratio: 2.09, 95% confidence interval: 1.14-3.84, p = 0.007).

CONCLUSION

In this preliminary study, plasma LPS concentration was associated with both cognitive decline and cerebral SVD and significantly correlated with beneficial gut microbial metabolites. Plasma LPS may be a risk factor for cognitive decline.

Relationship Between Plasma Neurofilament Light Chain, Gut Microbiota, and Dementia: A Cross-Sectional Study

BACKGROUND

Previous studies have demonstrated associations between gut microbiota, microbial metabolites, and cognitive decline. However, relationships between these factors and neurofilament light chain (NfL; a disease-nonspecific biomarker of neural damage) remain controversial.

OBJECTIVE

To evaluate the associations between plasma NfL, gut microbiota, and cognitive function.

METHODS

We performed a cross-sectional sub-analysis of data from our prospective cohort study that was designed to investigate the relationship between gut microbiota and cognitive function. Patients who visited our memory clinic were enrolled and demographics, dementia-related risk factors, cognitive function, brain imaging, gut microbiomes, and microbial metabolites were assessed. We evaluated the relationships between the gut microbiome, microbial metabolites, and plasma NfL. Moreover, the relationships between plasma NfL and cognitive function were assessed using multivariable logistic regression analyses.

RESULTS

We analyzed 128 participants (women: 59%, mean age: 74 years). Participants with high (above the median) plasma NfL concentrations tended to be older, women, and hypertensive and have a history of stroke, chronic kidney disease, and dementia. Plasma NfL was also associated with cerebral small vessel disease. However, plasma NfL levels were not significantly correlated with gut microbial metabolites. Multivariable analyses revealed that a higher plasma NfL concentration was independently associated with the presence of dementia (odds ratio: 9.94, 95% confidence interval: 2.75-48.2, p < 0.001).

CONCLUSION

High plasma NfL concentration was independently associated with the presence of dementia as previously reported. However, plasma NfL levels were not significantly correlated with gut microbial metabolites in this preliminary study.

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

OBJECTIVE

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. The aims of this study were to evaluate the relationships between adherence to a Japanese-style diet, the gut microbiota, and cognitive decline. Furthermore, we aimed to evaluate the three forms of the Japanese diet index (JDI; the conventional [JDI₉], updated [JDI₁₂], and a newly modified JDI) to determine which would show the closest relationships with cognition and the gut microbiota.

METHODS

We performed a cross-sectional subanalysis of data from a prospective hospital-based cohort study. We assessed the patients' demographic characteristics, dietary composition, risk factors, cognitive function, brain imaging, gut microbiome, and microbial metabolites. On the basis of previous studies, a nine-component traditional JDI (JDI₉), a 12-component modern JDI (JDI₁₂), and a 12-component revised JDI (rJDI₁₂), were defined. We 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 participants (61% women; mean age: 74.6 ± 7.4 y). Compared with participants who had dementia, those without dementia were more likely to consume foods in the JDI₁₂, including fish and shellfish (64.5 versus 39.1%, P = 0.048), mushrooms (61.3 versus 30.4%, P = 0.015), soybeans and soybean-derived foods (62.9 versus 30.4%, P = 0.013), and coffee (71 versus 43.5%, P = 0.024). There were non-significant trends toward lower fecal concentrations of gut microbial metabolites in participants with a more traditional Japanese diet. Participants with dementia had lower JDI scores than those without dementia (dementia versus non-dementia, median JDI₉ score: 5 versus 7, P = 0.049; JDI₁₂: 7 versus 8, P = 0.017; and rJDI₁₂: 7 versus 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.

Predicting hemorrhagic transformation after large vessel occlusion stroke in the era of mechanical thrombectomy

Serum biomarkers are associated with hemorrhagic transformation and brain edema after cerebral infarction. However, whether serum biomarkers predict hemorrhagic transformation in large vessel occlusion stroke even after mechanical thrombectomy, which has become widely used, remains uncertain. In this prospective study, we enrolled patients with large vessel occlusion stroke in the anterior circulation. We analyzed 91 patients with serum samples obtained on admission. The levels of matrix metalloproteinase-9 (MMP-9), amyloid precursor protein (APP) 770, endothelin-1, S100B, and claudin-5 were measured. We examined the association between serum biomarkers and hemorrhagic transformation within one week. Fifty-four patients underwent mechanical thrombectomy, and 17 patients developed relevant hemorrhagic transformation (rHT, defined as hemorrhagic changes ≥ hemorrhagic infarction type 2). Neither MMP-9 (no rHT: 46 ± 48 vs. rHT: 15 ± 4 ng/mL, P = 0.30), APP770 (80 ± 31 vs. 85 ± 8 ng/mL, P = 0.53), endothelin-1 (7.0 ± 25.7 vs. 2.0 ± 2.1 pg/mL, P = 0.42), S100B (13 ± 42 vs. 12 ± 15 pg/mL, P = 0.97), nor claudin-5 (1.7 ± 2.3 vs. 1.9 ± 1.5 ng/mL, P = 0.68) levels on admission were associated with subsequent rHT. When limited to patients who underwent mechanical thrombectomy, the level of claudin-5 was higher in patients with rHT than in those without (1.2 ± 1.0 vs. 2.1 ± 1.7 ng/mL, P = 0.0181). APP770 levels were marginally higher in patients with a midline shift ≥ 5 mm than in those without (79 ± 29 vs. 97 ± 41 ng/mL, P = 0.084). The predictive role of serum biomarkers has to be reexamined in the mechanical thrombectomy era because some previously reported serum biomarkers may not predict hemorrhagic transformation, whereas the level of APP770 may be useful for predicting brain edema.

The Association between Cerebral Small Vessel Disease and the Gut Microbiome: A Cross-Sectional Analysis

BACKGROUND

Recent studies have demonstrated an association between the gut microbiome and cognitive function. However, the associations between the gut microbiome and brain parenchyma damage, and their underlying mechanisms, remain unclear.

MATERIALS AND METHODS

We performed a cross-sectional sub-analysis using data from our prospective cohort study to determine the association between the gut microbiome and cerebral small vessel disease (SVD). We assessed patient demographics, risk factors, cognitive function, brain imaging, voxel-based specific regional analysis system for Alzheimer's Disease (VSRAD, indicating brain atrophy), and the gut microbiome as indicated by enterotypes and faecal microbiome metabolites. We then analysed the associations between total SVD scores, cognitive function, and the gut microbiome.

RESULTS

We analysed data from 87 patients without dementia or a history of stroke, 64 of whom exhibited mild cognitive impairment. Higher total SVD scores were associated with cognitive decline and behavioural and psychological symptoms. Compared with all other patients, patients with enterotype I (Bacteroides >30%) were more likely to have cognitive decline (median scores: Mini-Mental State Examination, 25 vs. 27, P = 0.047; Clinical Dementia Rating-Sum of Boxes, 1.5 vs. 0.5, P = 0.002) and present with cerebral SVD and high VSRAD scores (1.01 vs. 0.57, P = 0.012). Furthermore, faecal metabolites were significantly higher in patients with higher total SVD scores compared with those with lower scores. Multivariable logistic regression analyses indicated that certain gut microbiomes may double the risk of white matter hyperintensity.

CONCLUSIONS

The gut microbiome is associated with cerebral SVD.

Relationship between dementia and gut microbiome-associated metabolites: a cross-sectional study in Japan

Dysregulation of the gut microbiome is associated with dementia. However, the relationship between microbiome-associated metabolites and dementia has yet to be identified. Outpatients visiting a memory clinic in Japan enrolled in this cross-sectional study; 107 subjects were eligible for the study, 25 of which had dementia. We collected demographics, activities of daily living, risk factors, cognitive function, and brain imaging data. The gut microbiome was assessed using terminal restriction fragment length polymorphism analysis. Concentrations of faecal metabolite were measured. We used multivariable logistic regression analyses to identify whether metabolites were independently related to dementia. The concentrations of metabolites were significantly different between subjects with and those without dementia. Every 1 standard deviation increment in faecal ammonia concentration was associated with around a 1.6-fold risk for the presence of dementia. A higher faecal lactic acid concentration was related to a lower risk of dementia, by around 60%. A combination of higher faecal ammonia and lactic acid concentrations was indicative of the presence of dementia, and had a similar predictive value as traditional biomarkers of dementia. Thus, faecal ammonia and lactic acid are related to dementia, independently of the other risk factors for dementia and dysregulation of the gut microbiome.

The relationship between the gut microbiome and mild cognitive impairment in patients without dementia: a cross-sectional study conducted in Japan

Recent studies have revealed an association between the dysregulation of the gut microbiome and dementia. However, whether this dysregulation is associated with mild cognitive impairment (MCI), an early stage of cognitive decline, in patients without dementia remains unclear. We performed a cross-sectional analysis to determine the association between the gut microbiome and MCI. Data, including patient demographics, risk factors, cognitive function, and brain imaging, were collected. The gut microbiome was assessed through terminal restriction fragment length polymorphism analysis. Multivariable logistic regression models were used to identify factors independently associated with MCI. Graphical modelling was used to illustrate mutual associations between MCI and identified factors. We analysed 82 patients, 61 of whom exhibited MCI. Patients with MCI had a higher prevalence of Bacteroides. Furthermore, patients with more Bacteroides were more likely to present with white matter hyperintensity and high voxel-based specific regional analysis system for Alzheimer's Disease (VSRAD) scores, indicating cortical and hippocampal atrophy. A multivariable logistic regression analysis revealed that a greater prevalence of Bacteroides was independently associated with MCI. Graphical modelling also showed a close association between Bacteroides and MCI. In conclusion, an increased prevalence of Bacteroides is independently associated with the presence of MCI in patients without dementia.

Cerebral Small Vessel Disease (CSVD) - Lessons From the Animal Models

Cerebral small vessel disease (CSVD) refers to a spectrum of clinical and imaging findings resulting from pathological processes of various etiologies affecting cerebral arterioles, perforating arteries, capillaries, and venules. Unlike large vessels, it is a challenge to visualize small vessels in vivo, hence the difficulty to directly monitor the natural progression of the disease. CSVD might progress for many years during the early stage of the disease as it remains asymptomatic. Prevalent among elderly individuals, CSVD has been alarmingly reported as an important precursor of full-blown stroke and vascular dementia. Growing evidence has also shown a significant association between CSVD's radiological manifestation with dementia and Alzheimer's disease (AD) pathology. Although it remains contentious as to whether CSVD is a cause or sequelae of AD, it is not far-fetched to posit that effective therapeutic measures of CSVD would mitigate the overall burden of dementia. Nevertheless, the unifying theory on the pathomechanism of the disease remains elusive, hence the lack of effective therapeutic approaches. Thus, this chapter consolidates the contemporary insights from numerous experimental animal models of CSVD, to date: from the available experimental animal models of CSVD and its translational research value; the pathomechanical aspects of the disease; relevant aspects on systems biology; opportunities for early disease biomarkers; and finally, converging approaches for future therapeutic directions of CSVD.

Analysis of the relationship between the gut microbiome and dementia: a cross-sectional study conducted in Japan

Dysregulation of the gut microbiome is associated with several life-threatening conditions and thus might represent a useful target for the prevention of dementia. However, the relationship between the gut microbial population and dementia has not yet been fully clarified. We recruited outpatients visiting our memory clinic to participate in this study. Information on patient demographics, risk factors, and activities of daily living was collected, and cognitive function was assessed using neuropsychological tests and brain magnetic resonance imaging scans. Faecal samples were obtained, and the gut microbiome was assessed by terminal restriction fragment length polymorphism (T-RFLP) analysis, one of the most well-established and reliable 16S ribosomal RNA-based methods for classifying gut microbiota. Patients were divided into two groups, demented and non-demented. Multivariable logistic regression models were used to identify the variables independently associated with dementia. The T-RFLP analysis revealed differences in the composition of the gut microbiome: the number of Bacteroides (enterotype I) was lower and the number of ‘other’ bacteria (enterotype III) was higher in demented than non-demented patients. Multivariable analyses showed that the populations of enterotype I and enterotype III bacteria were strongly associated with dementia, independent of the traditional dementia biomarkers. Further studies of the metabolites of gut microbes are needed to determine the mechanism underlying this association.