Biomarkers are now widely used in many fields of medicine, and the identification of biomarkers that predict antipsychotic efficacy and adverse reactions is a growing area of psychiatric research. Monoamine molecules of the peripheral bloodstream are possible prospective biomarkers based on a growing body of evidence indicating that they may reflect specific changes in neurotransmitters in the brain. The aim of this study was to detect peripheral biogenic amine indicators of patients with acute psychosis and to test the correlations between the biological measures studied and the psychopathological status of the patients. This research included 60 patients with acute psychosis treated with olanzapine (n = 30) or haloperidol (n = 30). Here, we measured biogenic amine indicators, including mRNA levels of dopamine receptor D4 (DRD4) and the serotonin 2A receptor (5HTR2A), in peripheral blood mononuclear cells (PBMCs) using quantitative real-time polymerase chain reaction and serum dopamine concentrations by enzyme linked immunosorbent assay (ELISA). Psychopathological status was evaluated using psychometric scales. The assessments were conducted prior to and after 14 and 28 days of treatment. The administration of haloperidol, but not olanzapine, up-regulated 5HTR2A mRNA in a linear manner, albeit without statistical significance (p = 0.052). Both drugs had non-significant effects on DRD4 mRNA levels. Nevertheless, a positive correlation was found between DRD4 and 5HTR2A mRNA levels over a longitudinal trajectory, suggesting co-expression of the two genes. A significant positive correlation was observed between 5HTR2A mRNA levels and total Positive and Negative Syndrome Scale (PANSS) scores in both groups of patients before treatment. A significant correlation between baseline 5HTR2A mRNA levels and PANSS scores on days 14 and 28 of treatment remained for patients treated with olanzapine only. Moreover, a significant positive correlation was observed between blood serum dopamine levels and scores on extrapyramidal symptom scales in the olanzapine group. The DRD4 and 5HTR2A genes are co-expressed in PBMCs during antipsychotic administration. Despite a correlation between the studied biogenic amine indicators and the psychopathological status of patients, reliable biomarkers of treatment response could not be determined.

— The 5-hydroxytrypamine (serotonin) 2A receptor (5-HTR2A) is the key receptor involved in the monoaminergic regulation of the body, which determines the biological functions and behavior of...

Background/Objectives: Clozapine, the gold-standard treatment for treatment-resistant schizophrenia, is linked to metabolic disturbances such as weight gain and metabolic syndrome (MetS). Methods: This systematic review and meta-analysis evaluated the association between HTR2C polymorphisms and these adverse effects. Following PRISMA guidelines, 27 studies (n = 4044 patients, including 1804 clozapine-treated) were analyzed. Results: A meta-analysis revealed that the rs3813929 T allele was associated with a smaller increase in body weight, showing a mean BMI difference of 0.59 kg/m² (95% CI: −1.02 to −0.17; *p* = 0.006), particularly in males. The rs1414334 C allele doubled MetS risk (OR: 2.15; 95% CI: 1.42–3.27; *p* = 0.0003). Haplotype analyses suggested combined genetic effects, though findings for other polymorphisms were inconsistent. Key limitations include study heterogeneity, small sample sizes, and the predominance of mixed antipsychotic regimens (clozapine with other psychotropics) in included studies, potentially confounding metabolic outcomes. Despite this, rs3813929 and rs1414334 emerge as promising pharmacogenetic markers for predicting metabolic risks. Conclusions: These results highlight the need for large-scale, prospective studies across diverse populations to validate associations and optimize personalized monitoring strategies. Implementing genetic screening could enhance early intervention, improving long-term outcomes for clozapine-treated patients.

Schizophrenia is one of the most serious and common mental disorders, which is characterized by high levels of pathogenic heterogeneity as well as neuroimmune abnormalities, which require treatment with antipsychotic drugs. Monoamines are one of the key neurotransmitters which play an important role in neuroimmune interactions of the human organism. We suggest that the quantity of the monoamine receptors on mononuclear cells of the peripheral blood (PBMCs) can be associated with the cytokine profile of patients. With this quantity being a key component of the mental status correction mechanism in antipsychotic therapy. In this study we measured cytokine levels (IL-6, IL-1b and TGF-b) in blood serum, the protein expression status of the serotonin receptor 5HTR2A and the dopamine receptors D1 (DRD1), DRD2, DRD3 in PBMCs of drug-naive, first episode schizophrenia patients before and after the treatment with olanzapine and haloperidol. This study has shown for the first time that the antipsychotic therapy leads to a decrease in protein levels of monoamine receptors in PBMCs associated with the affinity of the drug used. Blood cytokine levels were significantly higher in serum from studied patients as compared with the reference values. The antipsychotic-linked change of the TGF-b production caused by the therapy is probably associated with the reduction of various monoamine receptors. The relationship between the psychopathological status and the protein level of 5THR2A suggests that the amount of 5HTR2A may serve as a potential biomarker for the personalized appointment of the antipsychotic therapy.