Introduction: Schizophrenia and obsessive-compulsive disorder (OCD) are two chronic psychiatric disorders associated with partially overlapping cognitive impairments and neurobiological processes. The aim of this study was to comparatively examine neurocognitive performance and the expression levels of selected peripheral microRNAs (miR-134, miR-137, miR-150, miR-502, and miR-1306) in patients with schizophrenia and OCD relative to healthy controls, and to exploratorily assess potential heterogeneity within OCD by considering autogenous and reactive subtypes.
Methods: This cross-sectional study included 20 patients with schizophrenia, 20 patients with OCD, and 20 healthy controls matched for age, sex, and years of education. All participants underwent a standardized neurocognitive test battery assessing executive functions, attention, processing speed, and verbal memory. Plasma miRNA levels were measured from peripheral blood samples using quantitative real-time polymerase chain reaction (qRT-PCR). Within the OCD group, autogenous and reactive obsession subtypes were additionally analyzed.
Results: Both schizophrenia and OCD groups showed poorer performance than healthy controls in measures of attention, processing speed, and executive functioning. Verbal memory impairment was more widespread in the schizophrenia group, whereas it was more limited in the OCD group. After controlling for depression and anxiety levels as covariates, many neurocognitive differences remained significant. miR-134 levels were lower in the OCD group, while miR-502 levels were lower in both the OCD and schizophrenia groups compared with healthy controls. Exploratory analyses yielded limited findings suggesting a possible association between miR-502 and executive function measures.
Conclusion: The findings suggest a more widespread pattern of neurocognitive impairment in schizophrenia, whereas OCD appears to involve a more selective cognitive impairment characterized predominantly by executive dysfunction, with verbal memory difficulties potentially related to executive processes. Alterations in selected miRNA levels may provide exploratory clues regarding shared and distinct peripheral molecular processes, while the potential relationship between miR-502 and executive functioning warrants confirmation in larger and longitudinal studies.
Keywords: microRNAs, neuropsychological tests, obsessive-compulsive disorder,