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

Objective: The 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. Methods: We 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. Results: A significant [group x structure x side] interaction revealed outcome groups differed in hippocampus tail volumes; significantly on the left (non-remitted = 694 +/- 175 mm(3); remitted = 855 +/- 133 mm(3); p = 0.001) with a trend difference on the right (non-remitted = 723 +/- 162 mm(3); remitted = 833 +/- 126 mm(3); p = 0.023). Groups did not differ in body, head, or amygdala volumes bi-laterally. Conclusions: A 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. (C) 2010 Elsevier B.V. All rights reserved.