Neural markers of remission in first-episode schizophrenia : A volumetric neuroimaging study of the hippocampus and amygdala

Abstract

ObjektiveThe temporolimbic region has been implicated in the pathophysiology in schizophrenia. More specifically, significantly smaller hippocampal volumes but not amygdala volumes have been identified at onset in first-episode schizophrenia (FES) patients. However, volumetric differences (namely, in the hippocampus) exhibit an ambiguous relationship with long-term outcome. So, we examined the relationship between hippocampus and amygdala volumes and early remission status.MethodsWe compared hippocampus and amygdala volumes between 40 non-remitted and 17 remitted FES patients and 57 healthy controls. Amygdala and hippocampus were manually traced with the hippocampus additionally segmented into three parts: body, head, and tail. Remission was defined as mild or less on both positive and negative symptoms over a period of 6 consecutive months as per the 2005 Remission in Schizophrenia Working Group criteria.ResultsA significant [group × structure × side] interaction revealed outcome groups differed in hippocampus tail volumes; significantly on the left (non-remitted = 694 ± 175 mm3; remitted = 855 ± 133 mm3; p = 0.001) with a trend difference on the right (non-remitted = 723 ± 162 mm3; remitted = 833 ± 126 mm3; p = 0.023). Groups did not differ in body, head, or amygdala volumes bi-laterally.ConclusionsA smaller hippocampal tail volume may represent a neural marker in FES patients who do not achieve early remission after the first 6 months of treatment. The early identification of patients with poor outcome with respect to the hippocampus tail may encourage the search for new, more target-specific, medications in hope of improving outcome and moving us towards a better understanding of the pathophysiology of schizophrenia.