Psychiatric
evaluation relies on subjective symptoms and behavioral
observation, which sometimes leads to misdiagnosis. Despite previous
efforts to utilize plasma proteins as objective markers, the depletion
method is time-consuming. Therefore, this study aimed to enhance previous
quantification methods and construct objective discriminative models
for major psychiatric disorders using nondepleted plasma. Multiple
reaction monitoring-mass spectrometry (MRM-MS) assays for quantifying
453 peptides in nondepleted plasma from 132 individuals [35 major
depressive disorder (MDD), 47 bipolar disorder (BD), 23 schizophrenia
(SCZ) patients, and 27 healthy controls (HC)] were developed. Pairwise
discriminative models for MDD, BD, and SCZ, and a discriminative model
between patients and HC were constructed by machine learning approaches.
In addition, the proteins from nondepleted plasma-based discriminative
models were compared with previously developed depleted plasma-based
discriminative models. Discriminative models for MDD versus BD, BD
versus SCZ, MDD versus SCZ, and patients versus HC were constructed
with 11 to 13 proteins and showed reasonable performances (AUROC =
0.890–0.955). Most of the shared proteins between nondepleted
and depleted plasma models had consistent directions of expression
levels and were associated with neural signaling, inflammatory, and
lipid metabolism pathways. These results suggest that multiprotein
markers from nondepleted plasma have a potential role in psychiatric
evaluation.