Plasma amino acids altered in first-episode psychosis

Patients with first-episode psychosis (FEP) exhibit a low gamma amino-n-butyric (GABA) plasma profile, a recent study suggests.

The study included 166 FEP patients (mean age, 30.3±12.2 years; 64.0 percent male) and 76 unaffected siblings (mean age, 31.5±11.0 years; 30.3 percent male). The following plasma amino acids were measured through gas chromatography-mass spectrometry: glutamic acid, glutamine, glycine, proline, tryptophan, tyrosine, serine, and GABA. A parallel group of 166 community controls (mean age, 31.4±12.0 years; 63.9 percent male) was also included.

GABA plasma levels were significantly reduced among FEP patients as compared to both sibling (p=0.006) and community (p=0.048) controls.

On the other hand, sibling controls had lower plasma concentrations of glutamic acid, glutamic acid and glutamine, and proline as compared to both patients and controls. Levels of tryptophan, in contrast, was significantly elevated among siblings.

Glycine, glycine-to-glutamic acid ratio, glutamine, serine, and tyrosine levels did not differ among the participant groups.

In terms of clinical characteristics of FEP, the plasma amino acid profile did not vary in accordance to sex, age, smoking, and the use of psychoactive substances. Treatment also affected plasma amino acids, particularly glutamic acid. For instance, its levels were significantly lower among those with only 11 weeks of pharmacological treatment, as opposed to patients who had been treated for ≥12 weeks (p=0.009).

“Altogether, the peripheral blood alterations seen herein might reflect an imbalance of amino acids in psychosis. Further studies, especially metabolomics, are needed to confirm our findings and improve the understanding of psychosis pathogenesis,” the researchers said.