The above review has several important points to make with regard to the provision of services to prevent and treat comorbid drug and alcohol and psychiatric disorders. Firstly, the evidence suggests that it is feasible to prevent the onset of both psychiatric and substance abuse disorders if early intervention and prevention strategies are implemented during childhood and adolescence. It suggests that large-scale screening and brief interventions for young people may offset some of the costs that individual and comorbid disorders later impose on our health care system.

Another fact emphasised by this review is that this highly disabled group is not served particularly well within current service systems. Because the drug and alcohol and psychiatric services are administered and funded separately, there is generally little incentive for each to assess and treat comorbid conditions. Furthermore comorbidity is often used as an excluding factor in research carried out in either area. Thus not only are these people poorly served, but there is little research pushing for improvements in services provided to them. Yet the evidence, from epidemiology as well as clinical research, is clear that comorbidity contributes an inordinate amount to the work of the services. Those with comorbidity are over-represented in both primary and secondary treatment centres suggesting the additional disability that having both types of disorder confers, as well as suggesting that implementation of assessment and appropriate evidence-based interventions to deal with comorbid disorders may alleviate the pressure on services overall.

Yet, there are many barriers to effective change in service provision and one is the lack of sufficient well-designed research needed to specify best practice for the treatment of comorbidity. However, data is emerging which provides some general guidelines which ultimately would lead to improvements in service provision. Services which receive Government funding should be required to screen for comorbid disorders and to ensure best practice is implemented for both unitary and comorbid conditions. This requires ongoing training for service staff in order to update their knowledge and skills to ensure best practice and to help them commit to best practice. It also requires provision of standardised and manualised intervention packages at both primary care and within specialist services to assist implementation of best practice.