Five major psychiatric disorders: schizophrenia, major depressive disorder, bipolar disorder, autistic spectrum disorder, and attention-deficit/hyperactivity disorder, show a shared genetic background and probably share common pathobiological mechanisms. S100B is a calcium-binding protein widely studied in psychiatric disorders as a potential biomarker. Our systematic review aimed to compare studies on peripheral S100B levels in five major psychiatric disorders with shared genetic backgrounds to reveal whether S100B alterations are disease-specific. EMBASE, Web of Science, and PubMed databases were searched for relevant studies published until the end of July 2023. This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols (PRISMA) guidelines. Overall, 1215 publications were identified, of which 111 full-text articles were included in the systematic review. Study designs are very heterogeneous, performed mostly on small groups of participants at different stages of the disease (first-episode or chronic, drug-free or medicated, in the exacerbation of symptoms or in remission), and various clinical variables are analyzed. Published results are inconsistent; most reported elevated S100B levels across disorders included in the review. Alterations in S100B peripheral levels do not seem to be disease-specific.

Background: Impulsivity assessment may serve as a valuable clinical tool in the stratification of suicide risk. Acting without forethought is a crucial feature in the psychopathology of many psychiatric disturbances and corresponds with suicidal ideations, behaviors, and attempts. Methods: We present data on biological and psychological correlates of impulsivity among young adults (n = 47). Psychological analysis included both the self-description questionnaire—Barratt Impulsiveness Scale (BIS-11)—and neuropsychological behavioral tests, including the Iowa Gambling Task (IGT), the Simple Response Time task (SRT), and the Continuous Performance Test (CPT). mRNA and micro-RNA were isolated from peripheral blood mononuclear cells (PBMC). Expression levels of Brain-Derived Neurotrophic Factor (BDNF) mRNA and its regulatory micro RNAs, mir-1-3p, mir-15a-5p, mir-26a-5p, mir-26b-5p, and mir-195-5p, were analyzed using the quantitative reverse transcription polymerase chain reaction (RT-qPCR) method. proBDNF and BDNF plasma protein levels were quantified using enzyme-linked immunosorbent assay (ELISA). Results: Significant correlations between BDNF mRNA and mir-15a-5p as well as proBDNF levels and mir-1-3p were detected. proBDNF protein levels correlated with motor and perseverance, while mir-26b correlated with cognitive complexity subdimensions of the BIS-11 scale. Correlations between BDNF, miRNAs, and the results of neuropsychological tests were also detected. Conclusions: The BDNF pathway shows a clinical potential in searching for biomarkers of impulse-control impairment. BDNF-regulatory micro-RNAs are detectable and related to clinical parameters in the studied population, which needs further research.

Background/Objectives : The incidence of mood disorders in adolescents is increasing. Bipolar disorder is often misdiagnosed in the early stages of the disease due to the prevalence of depressive symptoms, while manic episodes occur later. Identifying predictors of diagnosis conversion could facilitate timely and appropriate treatment. Our study aimed to find correlations of selected peripheral protein levels with temperament and character traits in adolescents diagnosed with major depressive disorder and bipolar disorder. Methods: A group of adolescents and young adults diagnosed with major depressive disorder (MDD, n = 50) or bipolar disorder (BD, n = 24) was enrolled in the study during the exacerbation of symptoms and followed up over two years. Diagnosis conversion from MDD to BD was monitored. The Temperament and Character Inventory was applied, and BDNF, proBDNF, EGF, MIF, SCF, S100B, TNF-alpha, and IL-8 serum levels were measured. Spearman’s rank correlation analysis was conducted. Results: We found different patterns of correlations in MDD (TNF-alpha, IL-8, EGF, S100B with reward-dependence, self-directedness, and empathy) and BD (BDNF and EGF with persistence novelty-seeking and self-transcendence). Significant correlations were found in a group with diagnosis conversion. Conclusions: The findings of our study have the potential to significantly impact our understanding and treatment of mood disorders. Correlations obtained in the subgroup with diagnosis conversion may contribute to the development of prognostic markers in the future. Evaluating temperament and character traits alongside established biomarkers may offer a valuable method for predicting the conversion of mood disorders in adolescents, facilitating early and effective pharmacotherapy.