To elucidate the relevance of gut dysbiosis in Parkinson’s disease (PD) in disease progression, we made random forest models to predict the progression of PD in two years by gut microbiota in 165 PD patients. The area under the receiver operating characteristic curves (AUROCs) of gut microbiota-based models for Hoehn & Yahr (HY) stages 1 and 2 were 0.799 and 0.705, respectively. Similarly, gut microbiota predicted the progression of Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) III scores in an early stage of PD with AUROC = 0.728. Decreases of short-chain fatty acid-producing genera, Fusicatenibacter, Faecalibacterium, and Blautia, as well as an increase of mucin-degrading genus Akkermansia, predicted accelerated disease progression. The four genera remained unchanged in two years in PD, indicating that the taxonomic changes were not the consequences of disease progression. PD patients with marked gut dysbiosis may thus be destined to progress faster than those without gut dysbiosis.

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is an autosomal dominant neurodegenerative disorder, which has three cardinal features: behavioral and personality changes, cognitive impairment, and motor symptoms. FTDP-17 was defined during the International Consensus Conference in Ann Arbor, Michigan, in 1996. The prevalence and incidence remain unknown but FTDP-17 is an extremely rare condition. It is caused by mutations in the tau gene, which encodes a microtubule-binding protein. Over 100 families with 38 different mutations in the tau gene have been identified worldwide. The phenotype of FTDP-17 varies not only between families carrying different mutations but also between and within families carrying the same mutations. The pathogenetic mechanisms underlying the disorder are thought to be related to the altered proportion of tau isoforms or to the ability of tau to bind microtubules and to promote microtubule assembly. Definitive diagnosis of FTDP-17 requires a combination of characteristic clinical and pathological features and molecular genetic analysis. Genetic counseling should be offered to affected and at-risk individuals; for most subtypes, penetrance is incomplete. Currently, treatment for FTDP-17 is only symptomatic and supportive. The prognosis and rate of the disease's progression vary considerably among individual patients and genetic kindreds, ranging from life expectancies of several months to several years, and, in exceptional cases, as long as two decades.

Safinamide is a reversible and selective monoamine oxidase-B (MAO-B) and sodium channel inhibitor with demonstrated efficacy in mid-to late-stage Parkinson's disease (PD) as an adjunct to l-DOPA. This study aimed to confirm the efficacy and safety of safinamide in PD patients with wearing-off. This 24-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study included Japanese PD patients with wearing-off on l-DOPA treatment. Patients were randomized to receive placebo (P), safinamide 50 mg/day (S50), or safinamide 100 mg/day (S100). The primary endpoint was the change from baseline in mean daily ON-time without troublesome dyskinesias (ON-time). Other measures included the changes in mean daily OFF-time, the unified Parkinson's disease rating scale (UPDRS) score, and the PDQ-39 summary index. A total of 406 subjects were randomized, of whom 349 completed the study. Baseline characteristics were balanced. Differences in the change of mean daily ON-time at Week 24 compared with the P group were 1.39 h (p = 0.0002) in the S50 group and 1.66 h (p < 0.0001) in the S100 group. Changes from baseline in mean daily OFF-time, UPDRS Part II total score (OFF phase), UPDRS Part III total score (ON phase), and UPDRS Part I also showed significant improvements. Adverse events occurred in 58.9%, 60.2%, and 61.4% of the P, S50, and S100 groups, respectively. The most common adverse drug reactions were dyskinesias (2.1%, 8.3%, and 10.6%) and visual hallucinations (1.4%, 3.0%, and 4.5%). As an adjunct to l-DOPA, safinamide safely increased ON-time and improved PD symptoms/signs in PD patients with wearing-off.

We aimed to identify gut microbial features in Parkinson’s disease (PD) across countries by meta-analyzing our fecal shotgun sequencing dataset of 94 PD patients and 73 controls in Japan with five previously reported datasets from USA, Germany, China1, China2, and Taiwan. GC-MS and LC-MS/MS assays were established to quantify fecal short-chain fatty acids (SCFAs) and fecal polyamines, respectively. α-Diversity was increased in PD across six datasets. Taxonomic analysis showed that species Akkermansia muciniphila was increased in PD, while species Roseburia intestinalis and Faecalibacterium prausnitzii were decreased in PD. Pathway analysis showed that genes in the biosyntheses of riboflavin and biotin were markedly decreased in PD after adjusting for confounding factors. Five out of six categories in carbohydrate-active enzymes (CAZymes) were decreased in PD. Metabolomic analysis of our fecal samples revealed that fecal SCFAs and polyamines were significantly decreased in PD. Genes in the riboflavin and biotin biosyntheses were positively correlated with the fecal concentrations of SCFAs and polyamines. Bacteria that accounted for the decreased riboflavin biosynthesis in Japan, the USA, and Germany were different from those in China1, China2, and Taiwan. Similarly, different bacteria accounted for decreased biotin biosynthesis in the two country groups. We postulate that decreased SCFAs and polyamines reduce the intestinal mucus layer, which subsequently facilitates the formation of abnormal α-synuclein fibrils in the intestinal neural plexus in PD, and also cause neuroinflammation in PD.