Neuroglia Alterations in the Olfactory Bulbs in Patients with Schizophrenia: An Exploratory Postmortem Study

The human olfactory bulb is a promising structure for the investigation of central nervous system disorders, including dementias of various etiologies. In Alzheimer's disease, anosmia is among the earliest clinical manifestations. Although olfactory disturbances have also been reported in schizophrenia, alterations within the olfactory system remain insufficiently studied. The aim of this study was to identify changes in the olfactory bulbs of patients with schizophrenia. Olfactory bulbs obtained from patients with schizophrenia (n = 23) and individuals without identified nervous system pathology (n = 23) were examined. Patients with schizophrenia demonstrated a statistically significant decrease in the immunoreactive area of myelin basic protein and a significant increase in the immunoreactive area of glial fibrillary acidic protein compared with the control group. In addition, the thickness of the layer of incoming olfactory nerve fibers was significantly reduced in the schizophrenia group. Overall, our findings demonstrate neuroglial alterations in the human olfactory bulb in schizophrenia. Together with observations from other brain regions, these results may indicate that the identified changes are systemic rather than localized in nature.