Distinct salivary microbiota profiles, BDNF DNA methylation and miR-16-5p, miR-29a-3p, miR-191-5p alterations in Obsessive-Compulsive Disorder and Major Depressive Disorder

Obsessive-Compulsive Disorder (OCD) and Major Depressive Disorder (MDD) often co-occur, with OCD symptoms influencing MDD development and vice versa. Finding biomarkers is crucial to enhancing diagnosis and care. Although there has been much research on the function of gut microbiota in mental illnesses, this study by Girella et al. (2025) focuses on the alterations in oral microbiota and their relationship to BDNF (Brain-Derived Neurotrophic Factor) DNA methylation in OCD and MDD patients in comparison to healthy controls. The study finds significant changes in microbiota composition: OCD patients have higher levels of Actinobacteriota and Firmicutes, while MDD patients show increased Actinobacteriota and Firmicutes, and decreased Bacteroidota and Proteobacteria. These alterations, possibly linked to post-streptococcal autoimmunity, emphasize the microbiota’s role in the pathophysiology of both disorders. The authors also demonstrated that significant decreases in OCD and MDD were linked to certain alterations in BDNF DNA methylation at CpG sites in exon I and IV. The expression of BDNF-targeting microRNAs was shown to be changed by microRNA analysis; in OCD, miR-16-5p and miR-29a-3p were upregulated, whereas, in MDD, miR-29a-3p and miR-191-5p were downregulated. These findings establish saliva as a non-invasive biomarker tool by pointing to disorder-specific microbiota and epigenetic patterns. This study advances our knowledge of the microbial-epigenetic relationships between OCD and MDD, which may help with focused treatments and early detection. [NPID: OCD, MDD, oral microbiota, BDNF DNA methylation, epigenetic profiles, salivary biomarkers, psychiatric disorders]

Year: 2025

Reference: Girella, A., Vismara, M., O’Riordan, K. J., Gunnigle, E., Mercante, F., Girone, N., Pucci, M., Gatta, V., Konstantinidou, F., Stuppia, L., Cryan, J. F., Dell’Osso, B., & D’Addario, C. (2025). Distinct salivary microbiota profiles, BDNF DNA methylation and miR-16-5p, miR-29a-3p, miR-191-5p alterations in Obsessive-Compulsive Disorder and Major Depressive Disorder. https://doi.org/10.1101/2025.01.24.25321067

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