Substance-Specific Treatment Responses and Resistance Patterns in Induced Psychoses: A Scoping Review of Antipsychotic Efficacy

<b>Objective:</b> To scope the available literature on antipsychotic treatment in substance-induced psychotic disorders, summarize evidence across substance categories, and highlight priorities for future research. <b>Methods:</b> This scoping review followed Arksey and O'Malley's framework and PRISMA-ScR guidelines. A systematic search of PubMed, Scopus, Embase, PsycINFO, and Cochrane Library (January 1985-August 2025) identified studies examining antipsychotic treatment in cannabis-, stimulant-, and hallucinogen-induced psychoses. Two reviewers independently screened studies and extracted data using a standardized form. Given marked heterogeneity, findings were synthesized descriptively. <b>Results:</b> Seventeen studies met inclusion criteria: 3 randomized controlled trials (17.6%), 10 observational studies (58.8%), and 4 case series (23.5%). Most evidence involved cannabis-induced (n = 7) and methamphetamine-induced (n = 6) psychosis. Randomized trials showed comparable efficacy between risperidone and haloperidol for cannabis-induced psychosis, and between quetiapine and haloperidol for methamphetamine-induced psychosis. Case series suggested potential benefits of third-generation antipsychotics such as lurasidone and cariprazine. No controlled studies were identified for cocaine- or hallucinogen-induced psychoses. <b>Conclusions:</b> Evidence for antipsychotic treatment in substance-induced psychoses remains scarce and uneven. While conventional antipsychotics appear effective for cannabis- and methamphetamine-related presentations, other substances remain virtually unstudied. Substantial evidence gaps and limited methodological quality highlight urgent research needs.