by Terrance Hunsley

The Campbell Collaboration has carried out a study of studies – an  analysis of evaluations of various kinds of service interventions to reduce substance abuse. Since the evaluations are each a “meta-evaluation” – another layer of compilation of results of studies – the overall number of situations and services evaluated, is substantial. The results may not seem dramatic, but they are significant. Such is life in the world of evidence-based analysis.  

The researchers looked at various kinds of interventions, from cognitive behavioural therapy – based counselling, to family interventions, to short-term solution-seeking interventions, to policing methods, to therapeutic and supportive communities, prison-based therapy, and drug courts.  

In many cases the evidence base was insufficient for substantive conclusions, especially when comparing different kinds of interventions.  But overall the results showed modest success, especially in time-limited interventions.  Successful counselling and therapy seems to require ongoing support. One intervention which does seem to have longer term success is drug courts, which worked better with adults than with juveniles. In this case, the long term measure was recidivism (re-arrest) which might not equate to other measures of substance abuse. Recidivism was reduced by about 17-25%, depending on the situation, role of the judge, and other supports. 

The researchers concluded that policy makers have a range of choices of intervention which can have modest success, and depending on the situation, some cost-savings to social systems. But for the most part, the success is time-limited. 

It is difficult to be optimistic about the present service model for dealing with substance abuse. In my mind, the results perhaps speak more for extending the harm reduction and maintenance approaches, and for other means of providing long term support.

For more info, Campbell Policy Brief No. 6 February 2020, at campbellcollaboration.org.