Substance-induced Psychotic Disorders Cause Convergent Cognitive Impairment to Schizophrenia Spectrum Disorders: A meta-analysis of Comparative Studies

Key findings from this study

This research indicates that:

• Cognitive impairment across memory, attention, psychomotor speed, and intellectual functioning is comparable between schizophrenia spectrum and substance-induced psychotic disorder.
• Executive function performance showed subtle but statistically significant relative advantage in substance-induced psychotic disorder, representing a potential differential feature.
• Substance-induced psychosis produces cognitive consequences of severity equivalent to schizophrenia despite distinct etiological origins.

Overview

This meta-analysis compared cognitive functioning between schizophrenia spectrum disorders and substance-induced psychotic disorder. Eighteen studies comprising 1092 patients were systematically reviewed and pooled using random effects modeling. Effect sizes were standardized using Hedges' g to correct for positive bias in Cohen's d.

Methods and approach

Systematic searches of PubMed, Web of Science, and Google Scholar identified comparative studies. The QUADAS-2 tool assessed risk of bias. Reported means and standard deviations from included studies were converted to Hedges' g and analyzed using random effects models. Cognitive domain analyses examined executive functions, memory, attention, psychomotor speed, and intellectual functioning separately.

Results

The overall meta-analysis detected no significant difference between diagnostic groups. Domain-specific analyses revealed a subtle but significant difference in executive functions, with substance-induced psychotic disorder showing relatively better performance. Performance on memory, attention, psychomotor speed, and intellectual functioning measures was comparable between groups, indicating substantial cognitive equivalence.

These findings suggest that cognitive impairment severity in schizophrenia and substance-induced psychotic disorder may converge despite differing etiological pathways. The convergent impairment pattern indicates that substance use leading to psychosis produces cognitive dysfunction of comparable magnitude to that observed in schizophrenia across most cognitive domains.

Implications

The cognitive similarity between diagnostic groups challenges assumptions about domain-specific impairment patterns as reliable diagnostic markers. Executive function performance emerged as a potential differential feature, suggesting its evaluation may contribute to clinical differentiation when diagnostic ambiguity exists. However, the substantial overlap in cognitive profiles indicates that cognitive testing alone cannot definitively distinguish these conditions.

Findings support consideration of substance-induced psychotic disorder as producing severe and persistent cognitive consequences equivalent to schizophrenia-related impairment. This has relevance for prognosis estimation, rehabilitation planning, and understanding the neurobiological impact of substance-related psychosis. Future research should clarify whether executive function differences reflect genuine diagnostic distinctions or represent effects of substances on prefrontal systems.

Scope and limitations

This summary is based on the study abstract and available metadata. It does not include a full analysis of the complete paper, supplementary materials, or underlying datasets unless explicitly stated. Findings should be interpreted in the context of the original publication.