warfare, territorial expansion, and cultural evolution

Abstract

Hippocampal volume reduction spe -cific for later transition to psychosis or substance-associated effects? We read with great interest the article by Witthaus and colleagues 1 recently published in the Journal of Psychiatry and Neuroscience. The authors found that, compared with controls, patients at ultra-high risk (UHR) had signifi-cantly smaller volumes of the hip-pocampus corpus and tail bilaterally. The UHR patients who later devel-oped psychosis had smaller right hip-pocampus corpus and tail volumes than did those who did not develop psychosis. The authors concluded that the hippocampal volume reduction may be indicative of the prodromal phase of schizophrenia and may repre-sent a risk factor for transition into psychosis. However, significantly reduced (right) hippocampal volumes in UHR patients with later transition are in contrast to previous region-of-interest studies. We and others 2,3 showed no volumetric hippocampal differences between converters and nonconverters, suggesting that hippocampal volumes are not related to an at-risk mental state with later transition to psychosis. Instead, there is evidence for hip-pocampal and parahippocampal vol-ume reductions developing as the dis-ease progresses, at least during the first psychotic episode. 4,5 These inconsistent results may be at-tributable to different ascertainment strategies, transition criteria, clinical follow-up periods, cannabis abuse and medication effects. 6 Witthaus and col-leagues 1 reported that within 9 months after magnetic resonance imaging, 2 UHR patients made the transition to psychosis, and 6 patients were lost to clinical follow-up and therefore con-sidered to be converters (assumption based on available clinical informa-tion). In contrast to our and other pre-vious neuroimaging studies, patients at high risk of psychosis were fol-lowed-up for at least 1 year, and stan-dardized criteria 7 were applied to de-termine if any patients made the tran-sition to psychosis. In addition, Witthaus and colleagues