How effective is motivational interviewing for reducing substance abuse?
The evidence was mostly of low quality. Motivational interviewing is a brief intervention. Given it involves only 1 to 4 sessions, one should not expect too much regarding changes in drug abuse outcomes. Motivational interviewing and other interventions share a number of non-specific therapeutic factors, such as attention and therapeutic alliance. These factors may have a much greater influence on outcome than the contribution made by approachspecific theory and technique. In an early review of empirical studies cited,common therapeutic factors accounted for 30% of the therapeutic effect, technique 15%, expectancy (placebo effect) 15%, and spontaneous remission 40%.1
There are 76.3 million people with alcohol use disorders worldwide and 15.3 million with drug use disorders. Motivational interviewing is a client-centred, semi-directive method for enhancing intrinsic motivation to change by exploring and resolving ambivalence. The client and counsellor typically meet between 1 and 4 times for about 1 hour each time. The intervention is used widely, so, therefore, it is important to determine whether it helps, harms or is ineffective.