Altered hippocampal shape morphology in schizophrenia and at-risk mental state

Structural and functional alterations of the hippocampus have been reported to be associated with prodromal symptoms of psychotic disorders in individuals with an at-risk mental state (ARMS), as well as with the pathophysiology and symptomatology of psychotic conditions such as schizophrenia (SZ).

In this study, 3-tesla 3D MRI scans were obtained from 81 SZ patients, 56 individuals with ARMS, and 90 healthy controls. We evaluated hippocampal surface morphology using large deformation diffeomorphic metric mapping and conducted cluster-wise comparisons of the hippocampal surfaces across the groups.

A common surface expansion in the right cornu ammonis (CA)3 was observed in SZ and ARMS groups compared to healthy subjects. In SZ patients, additional surface expansions were noted in the right CA1, hippocampal tail, and presubiculum. A higher dosage of antipsychotic medication was associated with surface compression in the bilateral hippocampal tail.

Common hippocampal surface alterations may underlie vulnerability to psychosis. Further surface expansions may be associated with the manifestation of overt psychotic symptoms. Such surface changes may be affected by antipsychotic medications.