Development of the motivation to use substance questionnaire

Background: The use of a substance is always accompanied by a motivation that pushes the subject to use and abuse the substance. This work reports the validation data of the MUS (Motivation to Use Substance), which measures and evaluates the motivation to use substances based on the dimension of resistance, confidence, pleasure, and relaxation. Methods: The validation process involved 605 subjects belonging to a clinical sample of patients who used substances. The sample was divided into two groups: on the first, consisting of 342 subjects, an exploratory analysis was carried out, and on the second, consisting of 263 subjects, a confirmatory analysis was carried out. For concurrent and convergent validation, the SCL-90 test (Symptom Check List-90) was administered for the measurement of addiction-related psychiatric symptoms, and the ASI (Addiction Severity Index) test was administered for the measurement of the severity of the addiction. Results and Conclusions: The MUS was found to be a robust test of construct validity, convergent, and concurrent. The results highlight gender and age differences for some of the MUS scales. Ultimately, MUS can be considered an excellent tool for structuring treatment programs for addiction services.