Therapist focus on ambivalence and commitment: a longitudinal analysis of Motivational Interviewing treatment ingredients.

The present study examines two core therapeutic principles of Motivational Interviewing (MI) with alcohol and other substance use disorders. Specifically, therapist focus on client ambivalence and commitment to change, as well as a more general indicator of goal assessment, were tested as process predictors of subsequent alcohol use across four sessions of Motivational Enhancement Therapy. Participants were adult alcohol users involved in a large multisite clinical trial (Project MATCH; two arms Aftercare [AC] and Outpatient [OP]). A series of multilevel models examined the effect of proposed MI ingredients on alcohol use (percent days abstinent; drinks per drinking day) over a 12-week treatment period, and whether these effects interacted with time and client baseline motivation. Therapist effort to elicit client commitment to change alcohol use was associated with greater rates of abstinence among both AC and OP participants, and reduced drinking quantity among OP participants. However, therapist focus on ambivalence was associated with greater drinking quantity among OP participants, and when motivation was low, among AC participants. Goal assessment was a marginal to nonsignificant predictor across outcomes, and all interactions with time were nonsignificant. Therapist-reported treatment foci are important to subsequent patterns of drinking within a multisession MI, but the role of ambivalence and discrepancy is worthy of further clinical and empirical consideration.