Clinical Variables and Peripheral Biomarkers Associated with Substance-Induced Psychotic Disorder: Differences Related to Alcohol, Cannabis, and Psychostimulant Abuse

Background: The present retrospective observational study aims to identify differences in clinical features and peripheral biomarkers among patients affected by substance-induced psychotic disorder (SIPD) according to the primary substance of abuse. Methods: A sample of 218 patients was divided into three groups according to the type of consumed substance: alcohol, cannabis, and psychostimulants. The three groups were compared using one-way analyses of variance (ANOVAs) for continuous variables and χ² tests for qualitative variables. After excluding the alcohol-induced psychotic disorder group, the same analyses were repeated. The statistically significant variables from these subsequent analyses were included in a binary logistic regression model to confirm their reliability as predictors of cannabis- or psychostimulant-induced psychotic disorder. Results: Psychotic cannabis abusers were younger (p < 0.01), with illness onset at an earlier age (p < 0.01). Alcohol consumers presented a longer duration of illness (p < 0.01), more frequent previous hospitalizations (p = 0.04) and medical comorbidities (p < 0.01), and higher mean Modified Sad Persons Scale scores (p < 0.01). Finally, psychostimulant abusers had a higher frequency of lifetime history of poly-substance use disorders (p < 0.01). A binary logistic regression analysis revealed that higher mean Brief Psychiatric Rating Scale scores (p < 0.01) and higher sodium (p = 0.012) and hemoglobin (p = 0.040) plasma levels were predictors of cannabis misuse in SIPD patients. Conclusions: Different clinical factors and biochemical parameters con be associated with SIPD according to the main substance of abuse, thus requiring specific management by clinicians.