Medial Temporal Lobe and Cortical Involvement: Neuroanatomical Signatures of Symptom Dimension Dominant Schizophrenia

Aims: Schizophrenia is a psychiatric disorder with diverse clinical presentations that have differential prognoses and treatment responses.We aimed to explore the differences in neuroanatomical patterns between groups of schizophrenia having different symptom dimensions from an openly available neuroimaging source.Methods: T1-weighted MRIs and symptom ratings (SAPS -Scale for Assessment of Positive Symptoms & SANS -Scale for Assessment of Negative Symptoms) were obtained from the open database SchizConnect (http://schizconnect. org/).Based on standard symptom remission criteria, subjects were grouped into Positive symptoms (n=29) and Negative symptoms predominant (n=84) groups and healthy controls (n=120).Structural-MRI analysis was performed on Freesurfer and the scanner site-harmonized brain volumes were compared across the 3 groups.Results: Negative-Predominant group compared to healthy controls had smaller bilateral hippocampus, right amygdala, left thalamus, bilateral superior frontal, right parsopercularis, right parstriangularis, bilateral middle temporal, left parahippocampal, left entorhinal, bilateral fusiform, bilateral superior parietal and left inferior parietal cortex.In contrast, the Positive-Predominant group demonstrated volumetric reductions in bilateral hippocampus, bilateral parahippocampal and left entorhinal cortex only, compared to healthy controls.Conclusions: Exclusive bilateral medial temporal lobar volumetric reduction underlies positive symptoms, but additional extensive cortical and subcortical volume loss underlies negative symptoms.Symptom dimensions rather than standard diagnostic entities have distinct neuroanatomical signatures implying significant heterogeneity within the diagnosis. .