Subcortical structures and cognitive dysfunction in first episode schizophrenia

Schizophrenia is associated with widespread cortical and subcortical abnormalities. Studies examining cognitive deficits in schizophrenia have historically focused on cortical deficits; however, many subcortical areas also support cognition. We sought to determine whether deficits in subcortical gray matter are linked to neurocognitive dysfunction in patients with first-episode schizophrenia. This study included 170 patients with first-episode schizophrenia and 88 healthy controls. Clinical symptoms, neurocognitive function, and structural images were assessed. Subcortical volumes were recorded. Patients had significant deficits in all cognitive domains, including processing speed, attention, memory, executive function and social cognition. Patients also demonstrated significantly smaller volumes in the amygdala, hippocampus, thalamus, and total cortical gray matter than did controls after Bonferroni correction for multiple comparisons. Reasoning/problem solving was significantly and positively correlated with the volume of the amygdala and nucleus accumbens in patients. Positive symptoms of psychosis were positively correlated with the volume of the amygdala and nucleus accumbens. In addition, the dose of antipsychotic medication was positively correlated with the volume of the amygdala, nucleus accumbens, caudate, putamen, and pallidum. In conclusion, schizophrenia is associated with profound cognitive deficits. Our findings suggest that subcortical structures contribute to specific domains of cognitive dysfunction in first-episode schizophrenia.