Changes in psychopathology and peripheral inflammation in schizophrenia patients initiating treatment with second-generation antipsychotics: a post-hoc analysis

Neuroinflammation has been proposed as a potential factor in the pathogenesis of schizophrenia and has been suggested to be both a state and a trait measure of the disease. However, the results of previous studies are inconsistent. The aim of the present study was therefore to investigate whether peripheral inflammatory markers such as C-reactive protein (CRP), the neutrophil-to-lymphocyte ratio (NLR), the monocyte-to-lymphocyte ratio (MLR), and the systemic immune-inflammation index (SII) can reliably indicate disease severity in schizophrenia. 116 (52.6% male) cases diagnosed with schizophrenia commencing monotherapy with a second-generation antipsychotic were included in this study. Next to baseline evaluation of sociodemographic and clinical data, the Positive and Negative Syndrome Scale (PANSS) was used at the beginning and after 2, 4, 8, 12, and 24 weeks of treatment. Blood samples were collected simultaneously to measure CRP levels, NLR, MLR, and SII. Linear mixed-effects models were used to investigate whether PANSS (sub)scores and inflammatory markers changed over time and whether they were associated with each other. We found a significant reduction of most PANSS (sub)scores from baseline to follow-up measurements, while CRP levels, NLR, MLR, and SSI did not change between measurements. Results did not show statistically significant associations between PANSS (sub)score changes and changes in markers of neuroinflammation. This was also true when controlling for sex, age, smoking status, and body-mass index. This study found no evidence of an association between the levels of peripheral inflammatory markers and disease severity in schizophrenia.