Dysbiosis of the Beneficial Gut Bacteria in Patients with Parkinson’s Disease from India Original paper

What was studied?

This original research article explored the gut microbiome signatures in Indian patients with Parkinson’s disease (PD) compared to healthy controls, focusing on dysbiosis and the abundance of specific bacterial taxa. The study utilized full-length 16S rRNA gene sequencing with Oxford Nanopore technology to achieve high-resolution microbial profiling. The core aim was to elucidate shifts in gut microbial composition associated with PD, particularly the underrepresentation or overrepresentation of taxa potentially relevant to disease pathophysiology. Special emphasis was placed on identifying microbial biomarkers linked with both PD and the common nonmotor symptom of functional constipation. The study also sought to relate these findings to global PD microbiome research and to highlight unique signatures in the Indian context, providing new data for the ongoing development of microbiome-based diagnostic and therapeutic strategies.

Who was studied?

The study population comprised 36 subjects from the southwest coast of India, including 23 clinically diagnosed PD patients and 13 healthy controls (spouses of PD patients, age >40 years), recruited from a tertiary care neurology clinic. The PD group was characterized by a mean age of 60 years, a mix of both genders, and a range of disease durations and severities. Controls were selected specifically to match dietary habits and minimize confounding due to significant diet-related microbiome variability. Exclusion criteria included secondary Parkinsonism, psychiatric illness, primary gastrointestinal pathology, and recent antibiotic use. Detailed demographic, clinical, and dietary data were collected, and clinical severity was assessed using standardized scales.

Most important findings

The study found a distinctly altered gut microbiome in PD patients compared to healthy controls, with several notable shifts at both the family and genus levels. Key findings included a higher abundance of Clostridia, Christensenellaceae, and Oscillospiraceae in PD, and a lower abundance of beneficial short-chain fatty acid (SCFA) producers such as Lachnospiraceae, Coriobacteriaceae, Faecalibacterium, Fusicatenibacter, Roseburia, and Blautia. These SCFA-producing taxa are crucial for gut barrier integrity and anti-inflammatory effects, and their depletion in PD is consistent with global studies linking dysbiosis to disease progression and neuroinflammation.

Significantly, Clostridia was identified as overrepresented in Indian PD patients, a novel association not previously reported. At the genus level, Akkermansia, Dialister, Bacteroides, and Lachnospiraceae NK4A136 were positively correlated with functional constipation among PD cases—an important nonmotor symptom that affects quality of life. Alpha diversity (Shannon and Simpson indices) was reduced in PD, and beta diversity analysis confirmed distinct microbial community structures between PD and controls. Random forest and LEfSe analyses reinforced the significance of these taxa as potential biomarkers for PD and PD-associated constipation.

Key implications

This study reinforces the robust association between gut microbiome dysbiosis—specifically the depletion of SCFA-producing bacteria—and Parkinson’s disease, mirroring global patterns but also revealing unique features in the Indian population, such as the enrichment of Clostridia UCG_014. These findings underline the potential of using gut microbiome signatures as biomarkers for PD diagnosis and progression, while also highlighting targets for therapeutic intervention. The strong link between specific genera (e.g., Akkermansia, Bacteroides, Dialister, Lachnospiraceae NK4A136) and functional constipation in PD suggests that microbiome modulation could alleviate both motor and nonmotor symptoms. The study’s approach—using full-length 16S rRNA sequencing and controlling for dietary confounders—sets a methodological benchmark for future research. However, larger, longitudinal studies are needed to clarify causal relationships and support the development of personalized, microbiome-targeted therapies in PD management.

Citation

Pavan S, Gorthi SP, Prabhu AN, Das B, Mutreja A, Vasudevan K, Shetty V, Ramamurthy T, Ballal M. Dysbiosis of the Beneficial Gut Bacteria in Patients with Parkinson’s Disease from India. Ann Indian Acad Neurol. 2023;26(6):908-916. doi:10.4103/aian.aian_460_23