the increased NA in both the BPD without psychosis and the BPD with psychosis and not in the group with SZ suggests that this finding may be relatively specific to bipolar illness processes.

Our finding of a reduced thalamic volume in SZ and not BPD suggests that the thalamus may be more intimately involved in the SZ phenotype

we did find that amygdala volumes in the BPD without psychosis group correlated inversely with the MRS, which suggests the involvement of this structure in the clinical phenotype.

the most consistently reported finding in early-onset BPD is a reduced amygdala volume16 and in early-onset SZ, a decreased hippocampal volume.

we found that youths with SZ had the smallest thalamic volumes bilaterally, with at least a moderate effect size when compared with the other 3 groups

We found that there were no volumetric differences between SZ and BPD in the amygdala and the hippocampus, which was not consistent with our a priori hypothesis.

This study investigated the volumetric differences in subcortical gray matter volumes, particularly the amygdala and the hippocampus, in early-onset BPD without psychosis, BPD with psychosis, and SZ in order to elucidate the diagnostic specificity of patterns of subcortical neural abnormality. In addition, this study evaluated diagnosis-by-sex interactions to understand the influence of sexual dimorphism on the limbic structures.