Morphology of the orbitofrontal cortex in first-episode schizophrenia: relationship with negative symptomatology.

摘要

Different studies have documented OFC abnormalities in schizophrenia, but it is unclear if they are present at disease onset or are a consequence of disease process and/or drug exposure. The evaluation of first-episode, drug-naive subjects allows us to clarify this issue. Magnetic resonance imaging was performed on 43 first-episode, antipsychotic-naive schizophrenia patients and 53 healthy comparison subjects matched for age, gender, race, and handedness. Gray matter OFC volumes were measured blind to the diagnoses. As compared to controls, patients had greater volumes in left total OFC (p=0.048) and left lateral OFC (p=0.037). Severity of negative symptoms (anhedonia, flattened affect, and alogia) positively correlated with both the left lateral (Spearman's, rho=0.37, p=0.019; rho=0.317, p=0.041; r=0.307, p=0.048, respectively) and the left total OFC (Spearman's, rho=0.384, p=0.014; rho=0.349, p=0.023; rho=0.309, p=0.047, respectively). The present results suggest that first-episode, antipsychotic-naive schizophrenia subjects exhibit increased OFC volumes that correlate with negative symptoms severity. The OFC, through extensive and complex interconnections with several brain structures with putative role in pathophysiology of schizophrenia including amygdala, hippocampus, thalamus, DLPFC, and superior temporal lobe, may mediate schizophrenia symptoms such as blunting of emotional affect and impaired social functioning. Although the specific neuropathological mechanisms underlying structural abnormalities of the OFC remain unclear, increased OFC volumes might be related to deviations in neuronal migration and/or pruning. Future follow-up studies examining high-risk individuals who subsequently develop schizophrenia at different stages of disease could be especially instructive.