The schizo-obsessive spectrum: Mapping clinical phenotypes, neurobiological mechanisms, and treatment considerations in first-episode psychosis - An updated systematic review.

OBJECTIVES

Obsessive-compulsive symptoms (OCS) represent a prevalent comorbidity in first-episode psychosis (FEP) with significant implications for clinical presentation and treatment outcomes. This systematic review examines OCS prevalence, clinical characteristics, neurobiological correlates, and treatment approaches in FEP populations.

METHODS

Following PRISMA guidelines, we searched PubMed, Embase, PsycINFO, Web of Science, and Cochrane databases from inception to May 2025. Studies examining OCS in FEP patients (≤5 years from first episode) were included. Meta-analysis used random-effects models with Freeman-Tukey transformation. Quality assessment employed Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool.

RESULTS

Twenty-one studies encompassing 3989 participants were included. Meta-analysis revealed clinically significant OCS in 26.8 % (95 % CI: 18.2-37.1 %) of FEP patients and formal OCD diagnosis in 8.3 % (95 % CI: 6.1-11.2 %)-representing 3-4 fold elevations versus general population. OCS typically emerged 8-12 months before psychotic symptoms in 65 % of patients. Comorbid OCS patients demonstrated significantly higher positive symptom severity, depression scores, and functional impairment. Neuroimaging identified frontostriatothalamic abnormalities, including reduced orbitofrontal (Cohen's d: 0.48) and anterior cingulate cortex volume (Cohen's d: 0.43). Social cognitive deficits, particularly theory of mind impairments (58.3 % vs 71.2 % accuracy, p = 0.024), were enhanced in OCS patients. Treatment challenges included antipsychotic-induced OCS (38.9 % with clozapine vs 20.1 % olanzapine) and SSRI-related psychotic symptom exacerbation (16.7 %).

CONCLUSIONS

OCS affect one in four FEP patients, supporting a distinct "schizo-obsessive" subtype with specific neurobiological abnormalities and treatment considerations. Routine screening and integrated management protocols are essential for optimizing outcomes.