Plasma essential amino acid levels in first episode psychosis at baseline and after antipsychotic treatment.

This study assessed plasma levels of essential amino acids (EAA) in drug-naïve first episode psychosis (FEP) patients at diagnosis and after 10 weeks of antipsychotic treatment. Forty FEP patients were enrolled at baseline, with blood samples collected before and after a 10-week antipsychotic treatment period. Plasma EAA levels were measured using an LC/MS/MS method. Psychotic symptoms were evaluated using standardized inventories before and after treatment. A decrease in BPRS score of more than 40% was used to indicate treatment response. Thirty-five healthy volunteers served as the control group. Baseline plasma levels of Thr, Met, Leu, Lys, His, and Tyr were higher in FEP patients than in healthy controls. After 10 weeks of treatment, Leu, His, and Tyr increased further, primarily in treatment-responsive patients. Conversely, Val level was lower than controls in patients at baseline and remained unchanged after treatment. Increased EAA levels were correlated with lower (less severe) scores in positive symptom scales. Treatment non-responders had persistently low Tyr/large neutral amino acid (LNAA) ratio. Tyr/LNAA ratio increased after treatment, specifically in treatment-responders. Phe/Tyr ratio decreased post-treatment in both responder and non-responder groups. Elevated EAA levels in FEP patients may signify compensatory responses to increased physiological demand for neurotransmitters or energy. Combining specific EAA supplementation with antipsychotic treatment may enhance treatment response in these patients.