Comorbid mental disorders and substance use disorders: epidemiology, prevention and treatment

Intervention and community health issues in the prevention of internalising disorders, externalising disorders and substance use disorders

Page last updated: 2003

Efficacy vs. effectiveness
Low participation rates
Parent-child relationships where substance use disorders are involved
Service delivery

Efficacy vs. effectiveness

The extent to which intervention technologies can actually make a difference in the community is influenced by a number of pragmatic public health issues. Most of the intervention studies reviewed were a combination of effectiveness with efficacy trials. That is, while they were conducted in 'real world' settings, they evaluated the intervention under optimal delivery conditions, e.g., within the context of a funded research program, using careful experimental designs and measures, and implemented by highly trained and motivated staff. The question remains as to the community effectiveness of such interventions when implemented in the not-so-optimal conditions of existing mental health and educational systems. Many interventions are evaluated up to the efficacy trial stage and the community effectiveness remains unknown. In the area of prevention, effectiveness trials are essential and thus more work is needed to evaluate these interventions when implemented in community settings by non-specialist, non-research motivated staff.

Low participation rates

Recruitment of participants is one of the major obstacles of preventive interventions, regardless of the type of prevention. Because participants have not self-referred for treatment and may not even feel they have any problems, especially in early childhood, the sense of urgency and motivation that drives clinical interventions is often absent. With childhood anxiety problems, parents and teachers often have not even noticed anxiety problems, or often assume that children will 'grow out of it'. In the La Freniere and Capuano (1997) study of selected children, less than one-third of identified participants were successfully recruited. The Roth and Dadds (submitted) trial of a parenting intervention applied universally to preschool children has maintained contact with approximately half of those invited to participate. Indicated prevention projects in middle childhood show similar rates of recruitment. Although no adolescent studies were found specifically targeting adolescent anxiety problems, selected and indicated programs for depression in adolescents have typically achieved very low participation rates. The Shochet et al. (in press) school-based universal prevention of depression program received parental consent for 86% of potential students. However, when an additional parental component was added to the program, attendance by parents at three evening sessions was very low, with 36% attending one session and only 10% attending all three sessions.Top of page

With regard to substance use disorders, there may be more precise ways to use indicated and selected programs. The preventive and early intervention studies reviewed above either used universal interventions or targeted children already showing signs of the common mental disorders, or who are at risk of displaying problems due to the presence of risk factors such as family conflict or psychopathology. While there are many similarities in the risk factors for internalising, externalising and substance use disorders, there may be risk factors that are more relevant to identifying children particularly at risk for substance use disorders. Children of parents with existing substance use disorders is an obvious one. There is clear evidence that these children are at risk for substance use disorders themselves, as well as a range of other social and health problems (Chassin, Pitts, DeLucia, & Todd, 1999). The mechanisms of transmission appear to be a combination of specific biological risk for addiction as well as social adversity (O'Connor, Caspi, DeFries, & Plomin, 2000). Pragmatically, however, this is a difficult group to recruit effectively. While numerous programs have reported working with such children, the numbers are small and the ratio of participants to those offered participation is often not made clear. In contrast, for studies that have deliberately measured the success rates of recruiting children of parents with substance use disorders into intervention programs, the data is not encouraging (Gensheimer, Roosa, & Ayers, 1990; Michaels, Roosa, & Gensheimer, 1992). Understandably, identifying oneself as having a parent with a substance use problem is not appealing to young people, and few do. Thus, identification of young people at risk via direct family experience with substance use disorders may be a useful tertiary clinical strategy but is unlikely to offer much power as a larger community strategy. One solution to this is to offer such programs universally in schools with particular attention paid to the needs of children with substance abusing parents (e.g., Nastasi & DeZolt, 1994). Studies reviewed above indicate that recruiting young people via universal strategies and indicated and selected strategies for internalising disorders and externalising disorders have done well in reaching children potentially at risk for substance use disorders. As such, there is a good basis for arguing for increased attention to such programs.

Parent-child relationships where substance use disorders are involved

Caution must be used when findings on parent-child relationships are generalised to substance-using families. Positive relationships with peers and family are a common target in programs that aim to build resilience and reduce mental health problems in young people. As would be expected, these also form a central focus for many preventive programs for substance use disorders. However, it should be noted that the situation may be a little more complex with regard to substance use disorders than simply conceiving of positive interpersonal relationships as a protective factor. Modelling of substance use habits via close relationships is a key factor in the development of many forms of substance use and longitudinal studies show that adolescents are more likely to imitate substance use if they have a close relationship with the substance user (Andrews, Hops, & Duncan, 1997). Further, studies on families with opiate addiction show that positive family management practices have minimal protective influence on child development compared to that typically found in addiction free families (Gainey, Catalano, Haggerty, & Hoppe, 1997).Top of page

Service delivery

A final issue concerns the administrative systems that control the resource allocations and structures for mental health services. As we have seen, the most evidence to date that anxiety and depression problems can be prevented comes from school-based intervention trials. However, the responsibility for mental health promotion is typically within statutory health rather than education departments, and program designers may find their efforts frustrated by a lack of communication between the two groups. Inter-sectorial issues, concerned with the overlapping structure and functions of the various agencies that have responsibility for health and education of young people, are a major issue for the science and practice of prevention, particularly for substance use disorders where statutory responsibilities may span several agencies.