Schizophrenia severity, social functioning and hippocampal neuroanatomy: three-dimensional mapping study

BACKGROUND: Hippocampal shrinkage is commonly reported in schizophrenia, but its role in the illness is still poorly understood. In particular, it is unclear how clinical and psychosocial variables relate to hippocampal volumes. AIMS: To investigate neuroanatomic differences in the hippocampus using three-dimensional (3D) computational image analysis. METHOD: We used high-resolution magnetic resonance imaging and surface-based modelling to map the 3D profile of hippocampal differences in adults with schizophrenia (n = 67) and a healthy control group (n = 72). Manual tracings were used to create 3D parametric mesh models of the hippocampus. Regression models were used to relate diagnostic measures to maps of radial distance, and colour-coded maps were generated to show the profile of associations. RESULTS: There was no detectable difference between the schizophrenia and control groups in hippocampal radial distance. In the schizophrenia group, however, bilateral shape deflation was associated with greater illness severity (length of illness, positive and negative symptoms) and with poorer social functioning (educational level, quality of life and health status), which survived Bonferroni correction. CONCLUSIONS: Illness severity and poor social functioning may be associated with hippocampal deflation in schizophrenia. As a structural sign of poor outcome, imaging measures might help to identify a subgroup of patients who may need specific treatment to resist hippocampal shrinkage, such as cognitive rehabilitation or physical exercise.