Obsessive-compulsive disorder (OCD) has long been considered a condition rooted solely in brain function. However, a new study by Chinese researchers, published in the Journal of Affective Disorders, points to an unexpected factor: the state of the gut microbiota.

Using genetic analysis, the researchers identified six groups of bacteria directly associated with the risk of developing OCD. Some — including Proteobacteria, Ruminococcaceae, and Bilophila — were found to reduce the risk. Others, such as Bacillales and Eubacterium, appeared to increase it.

To determine causality rather than mere correlation, the team used Mendelian randomization — a method that leverages genetic data from nearly 220,000 people. Their findings suggest that shifts in gut microbiota composition may not just accompany OCD but actually contribute to its onset.

This is the first large-scale study to offer concrete evidence that gut bacteria can play a causal role in mental health disorders — not only in depression and anxiety, as previously assumed, but also in OCD.

The researchers hope this discovery will lead to new methods for preventing and treating OCD by targeting gut flora. This is especially significant for patients who do not respond well to existing therapies — a group that makes up nearly 40% of all OCD cases.

In a related study, scientists recently uncovered another unexpected health risk factor: the subjective feeling of low social status. This perception was strongly linked to signs of inflammation and fibrosis in heart tissue — particularly in women — even in the absence of overt symptoms.