Longitudinal analysis of astrocyte-derived protein levels in the blood of drug-naive and relapsed patients with schizophrenia

The potential influence of astrocytes on neuronal circuitry and psychotic symptoms in schizophrenia have recently been highlighted. Human postmortem studies have observed reduced astrocyte numbers in schizophrenia, but whether this pathology is present at disease onset or accumulates progressively with further psychotic episodes remains unclear. Therefore, we analysed serum levels of the astrocyte-derived proteins glial fibrillary acidic protein (GFAP) and fatty acid-binding protein 7 (FABP7) in acutely ill first-episode (n = 60) and relapsed (n = 34) schizophrenia patients compared to 94 matched controls. Measurements were taken before and 6 weeks after antipsychotic treatment. We found significantly lower levels of GFAP (p < 0.001) and FABP7 (p < 0.001) in patients compared to controls, with no significant differences between first-episode and relapsed patients or changes after treatment. FABP7 negatively correlated with age in controls (r = -0.319, p = 0.002), but not in patients (r = -0.251, p = 0.015). In contrast, GFAP showed no correlation with age. Our findings suggest that lowered GFAP and FABP7 may serve as trait markers of astrocyte pathology in schizophrenia, even prior to antipsychotic treatment. The absent correlation between FABP7 and age in schizophrenia patients, in contrast to controls, may be related to premature brain aging in schizophrenia. Long-term studies are needed to explore the relationship between chronic disease and astrocyte pathology in schizophrenia.