Scientists from Nanjing University have found that patients with an elevated neutrophil-to-lymphocyte ratio—a marker of systemic inflammation in the body—respond worse to standard treatment for mental disorders. The findings were published in the journal Biological Psychiatry (BioPsy).

Modern neuroimaging shows that different mental disorders—such as schizophrenia, major depressive disorder, and bipolar disorder—often share common neural mechanisms. However, the biological foundations of these conditions remain poorly understood.

In the new study, researchers sought to identify hidden “biotypes,” paying particular attention to brain inflammation—a suspected factor that may trigger the disorder in some patients but is largely inaccessible to direct measurement.

The study was conducted in two independent groups of volunteers. In the first stage, the researchers compared data on brain connectivity with molecular characteristics of the blood, including DNA methylation. This approach made it possible to identify a characteristic pattern of neural activity associated with immune system dysfunction.

In the second stage, the scientists found that patients with this neural “signature” had an increased neutrophil-to-lymphocyte ratio, a measure commonly used as an indicator of systemic inflammation.

Clinical data revealed another important consequence: during hospitalization, such patients responded less well to standard treatment methods. This suggests that the immune-inflammatory component of the disease directly affects treatment effectiveness.

According to lead author Fei Wang, the identified biomarker reflects the biological basis of the disorders and may also serve as a tool for predicting treatment response. The new findings also support the shift in psychiatry toward personalized medicine, in which therapy is tailored based on objective biological markers.