Measuring impaired control over cannabis use: Initial evaluation of the Impaired Control Scale-Cannabis (ICS-C)

Background: Impaired control is a central concept in addiction. Impaired control over alcohol has been associated with heavy drinking and alcohol-related problems in young adults, but there is less research on impaired control over cannabis. Currently, there is no validated self-report instrument that comprehensively assesses impaired control over cannabis use. This study examined the factor structure, reliability, and validity of a new measure, the Impaired Control Scale-Cannabis (ICS-C), which was adapted from the Impaired Control Scale (ICS) for alcohol (Heather et. al, 1993). Method: The sample consisted of students at two Canadian universities who reported past-month cannabis use (N=362; 63% women; 66% White, mean age=19.91). Participants completed an online survey including the ICS-C and ICS, along with measures of cannabis use, cannabis problems, alcohol use, impulsivity, and self-regulation. Results: After trimming problematic and redundant items, the final exploratory factor analysis of the ICS-C items yielded two factors: Attempted Control (attempts to control cannabis use) and Failed Control (unsuccessful attempts to limit cannabis use). High correlations between the ICS-C subscales and the Impaired Control subscale of the Marijuana Consequences Questionnaire provided evidence for convergent validity. Support for concurrent and discriminant validity was observed in the associations of the ICS-C subscales with cannabis use, cannabis problems, impulsivity, self-regulation, alcohol use, and the alcohol ICS. Conclusions: The ICS-C is a promising tool for assessing impaired control over cannabis in young adults. Future research should further validate the ICS-C and examine its potential clinical utility for identifying individuals at risk for cannabis use disorder.