Anatomic Abnormalities of Hippocampal Subfields in First-Episode Drug-Naïve Schizophrenia and Major Depressive Disorder: A Structural MRI Comparative Study

  Objective  To compare the structural changes along the longitudinal axis of hippocampus subfields between schizophrenia (SCZ) patients and major depressive disorder (MDD) patients in the early stage of their SCZ and MDD.

  Methods  Seventy-nine first-episode drug-naïve patients with SCZ, 48 first-episode drug-naïve patients with MDD, and 79 healthy controls (HC) were recruited and underwent assessment of clinical symptoms and magnetic resonance imaging (MRI) of the head. Following the calculation of hippocampal and subfield volumes with FreeSurfer, the volume of longitudinal subfields were summed up. Inter-group comparison of these indicators was made with the data of different groups and the correlation between clinical symptoms and the volumes of longitudinal subfields was analyzed.

  Results  Compared with HC, SCZ patients had smaller bilateral posterior hippocampus (left: t=−2.69, P=0.01; right: t=−2.90, P=0.004), while MDD patients exhibited no changes along the longitudinal axis of hippocampal subfields. In SCZ patients, the volume of bilateral posterior hippocampus was negatively correlated with the negative symptom scores of Positive and Negative Syndrome Scale (left: r=−0.29, P=0.01; right: r=−0.23, P=0.04).

  Conclusion  The smaller posterior hippocampus may be an imaging feature for distinguishing SCZ from MDD and may have contributed to the neuropathophysiological mechanism of SCZ in the early stage of the onset of the disease.