This is a Campbell Systematic Review of the effect of Multidimensional Family Therapy (MDFT) for treating abuse of cannabis, amphetamine, ecstasy or cocaine (referred to here as non-opioid drugs) among young people aged 11-21 years. The misuse of prescription drugs and the use of ketamine, nitrous oxide and inhalants such as glue and petrol are not considered in this review.

Youth drug abuse is a severe problem worldwide and recent reports describe ominous trends of youth drug abuse and a lack of effective treatment. This review is concerned with drug abuse that is severe enough to warrant treatment. It focuses on young people who are receiving MDFT specifically for non-opioid drug abuse.

MDFT is a manual-based, family-oriented treatment, designed to eliminate drug abuse and associated problems in young people’s lives. MDFT takes a number of risk and protective factors into account; the approach acknowledges that young people’s drug abuse is linked to dimensions such as home life, friends, school and community (Liddle et al., 2004). MDFT aims to modify multiple domains of functioning by intervening with the young person, family members, and other members of the young person’s support network (Austin et al., 2005). MDFT is thus based on a number of therapeutic alliances, with the young drug abuser, his or her parents and other family members, and sometimes with school and juvenile justice officials.

After a rigorous search of the literature, five randomized controlled studies with samples of 83-450 participants were identified. Three studies were conducted by MDFT program developers, one study was conducted by an independent investigator with the program developer as a co-author, and one study was conducted by independent investigators. Four studies were performed in the US, while the other was performed across five European countries.

We used meta-analytic procedures to summarise the available evidence on the effects of MDFT in comparison with other interventions on drug abuse, education, family functioning, risk behavior and retention in treatment. In this review, we interpret a value of the standardised mean difference, SMD=0.20 as a small effect size, in line with the general practice (Cohen, 1988). We note, however, the possibility that such a value might actually represent a larger effect if it is equivalent to a large reduction in the percentage of days a youth uses drugs, but we cannot comment further as we were unable to analyse the absolute effect of MDFT given that no studies comparing MDFT to no other treatment were available. The findings are as follows:
- On drug abuse: Based on the available evidence we conclude that MDFT has an effect on drug abuse reduction compared to other treatments, although the difference is small.
- On education: There is insufficient evidence to conclude whether MDFT has an effect on education compared to other treatments.
- On family functioning: There is no available evidence to conclude whether MDFT has an effect on family functioning compared to other treatments.
- On risk behavior and other adverse effects: There is no available evidence to conclude whether MDFT has an effect on risk behavior and other adverse effects compared to other treatments.
- On treatment retention: MDFT may result in improved treatment retention in young drug abusers compared to other interventions

The evidence found was limited as only five studies were included, and two studies had significant amounts of missing data. The evidence was very limited in terms of the outcomes reported on education, family functioning and risk behavior, and was insufficient for firm conclusions to be drawn on the effectiveness of the treatment with regard to such outcomes.

There is evidence that MDFT is slightly more effective in treating young people’s drug abuse than other treatments; however, the difference is small. Furthermore, none of the five included studies could be characterised as a robust RCT with a low risk of bias on all assessed domains. One study provided insufficient information on core issues for the risk of bias to be assessed and therefore we find reason to question the validity of this study.

Well-designed, randomized controlled trials within this population are needed. More research is also required to identify factors which modify the effect of MDFT and to identify which particular youth subgroups may be most likely to respond.