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

Abstract

Objektive<br /><br />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.<br />Methods<br /><br />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.<br /><br />Results<br /><br />A 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.<br /><br />Conclusions<br /><br />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.