Psychosis effect on hippocampal reduction in schizophrenia

•Psychotic relapse may lead to volume loss in the left hippocampus in schizophrenia.•There is also a disruption of gray matter - age relationship in the hippocampus.•Anatomical location of age and psychosis effects does not overlap.•Illness duration seems to be unrelated to the gray matter in the left hippocampus.

IntroductionIn schizophrenia, disruption of the neurodevelopmental processes may lead to brain changes and subsequent clinical manifestations of the illness. Reports of the progressive nature of these morphological brain changes raise questions about their causes. The possible toxic effects of repeated stressful psychotic episodes may contribute to the disease progression.ObjectivesTo analyze the influence of illness duration and previous psychotic episodes on hippocampal gray matter volume (GMV) in schizophrenia.MethodsWe performed an analysis of hippocampal GMV correlations with illness duration, number of previous psychotic episodes, and age in 24 schizophrenia patients and 24 matched healthy controls.ResultsWe found a cluster of GMV voxels in the left hippocampal tail that negatively correlated with the number of previous psychotic episodes, independent from the effect of age. On the other hand we found no effect of illness duration independent of age on the hippocampal GMV. Finally, we found a cluster of significant group-by-age interaction in the left hippocampal head.ConclusionsWe found an additive adverse effect of psychotic episodes on hippocampal morphology in schizophrenia. Our findings support toxicity of psychosis concept, together with etiological heterogeneity of brain changes in schizophrenia.