In the US, about one in every six adults has experienced a major depressive episode. In 2000 the annual cost of major depression to US taxpayers and businesses was estimated at $83 billion.

Depression is devastating to individuals and costly to the public purse. So the 83-billion-dollar question is this: how can depression best be prevented? Should interventions be aimed at whole populations or just those at risk?

In theory, universal programs – ones that target whole populations of people – are excellent candidates for preventive interventions. The evidence, however, doesn’t support this approach for the prevention of depression.

Targeted approaches, on the other hand, which focus on individuals at high risk of developing depression, are more successful. Approaches built on cognitive-behavior therapy and psycho-education are particularly effective. We have good evidence of the effectiveness of targeted approaches; but they are rarely implemented at scale. Programs known to be effective don’t reach the people that need them.

Where do we go from here? Universal prevention doesn’t work and though targeted approaches hold much promise their reach remains limited while scientists and policy-makers figure out how to take such programs to scale. Writing in a forthcoming edition of Prevention Science, a clinical psychologist from Harvard Medical School proposes a new agenda to guide future research into the prevention of depression.

Katie McLaughlin explores the pros and cons of universal and targeted approaches – and then takes the critical next step by asking: how can health programs really get to the social and economic roots of depression, such as childhood adversities, unemployment, poverty, and stress? The answer, she suggests, involves bringing the skills of mental health professionals together with the demographic and policy skills of public health professionals.

Goal 1: improve the efficacy of universal preventive intervention

The first goal, McLaughlin suggests, is to improve universal interventions. Several meta-analyses have revealed that universal preventions for depression don’t work. However, several benefits of universal prevention provide a strong argument for researchers to continue developing and testing new universal strategies for the prevention of depression.

First, universal prevention strategies are typically delivered by existing providers such as teachers and school counselors as part of their routine services. This approach is more sustainable, easier to implement in community settings and less expensive than targeted approaches, which are usually delivered by specially trained and experienced mental health professionals.

Second, universal prevention negates the need for the costly process of screening. McLaughlin cites one example of how expensive screening for targeted programs can be: “A cost-effectiveness study of a selective prevention intervention reported that the screening costs associated with the identification of 123 eligible participants totaled $45,213.”

Third, and by definition, a universal approach means that larger numbers of people receive the intervention. This might include individuals who are at high risk of developing depression but who are not picked up in screening efforts.

One emerging field that could hold promise for new universal strategies is internet- and technology-based intervention. This method is relatively inexpensive and does not rely on trained professionals to deliver the intervention. McLaughlin points out that “these approaches allow interventions to be delivered exactly as they are intended to be delivered. Evidence suggests that internet-based approaches to intervention delivery can be as effective as those delivered by clinicians and can reach substantial numbers of people for low cost.”

Goal 2: increase the reach and sustainability of indicated and selective preventive interventions

The second goal is to improve the sustainability of targeted interventions. Current evidence suggests that targeted approaches towards the prevention of depression do work. These kinds of programs have been found to be effective amongst high-risk adolescents, such as those with existing symptoms or family history of depression. Targeted approaches have also been found to prevent the onset of major depressive episodes among those with symptoms.

But there’s a downside to targeted approaches, too. Despite a comprehensive evidence base, the sustainable implementation and dissemination of targeted prevention programs in the community has thus far been lacking. McLaughlin explains that targeted approaches tend to be costly and time-consuming. What is more, although targeted prevention may work in tightly controlled environments for the purposes of research trials, substantial program drift has been observed when such programs are implemented in “real life” conditions. As a result, the potential benefits for psychological health are not realized.

How could targeted approaches overcome the challenge of sustainability? McLaughlin points to school- and internet-delivered approaches, which tend to be inexpensive and do not rely on highly qualified mental health professionals to administer the intervention. What’s more, new research is emerging that suggests non-professionals can achieve good results in certain contexts when supported by thorough training and ongoing technical assistance.

McLaughlin argues that an increase in screening amongst teachers, school counselors, primary care nurses and others already working on the frontline in community settings, coupled with the use of technology-based interventions, could dramatically increase the sustainability of prevention programs.

Goal 3: target upstream determinants of depression

The final goal of McLaughlin’s agenda concerns what she terms “upstream determinants of depression.” These are structural and economic factors in the fabric of society that are not traditionally targeted by mental health interventions. Examples of upstream determinants include childhood adversities, particularly child maltreatment, as well as poverty, unemployment and exposure to trauma or stressful life events.

McLaughlin explains that “individual patterns of thought, behavior, and emotion regulation - the targets of most mental health interventions - are not the primary focus. Rather, the goal of such an approach is to alter the social, economic, and structural factors that give rise to depression and thereby modify the distribution of risk factors for depression at a population.”

This approach requires mental health professionals to pool their skills with the demographic and policy skills of public health professionals. “Effective targeting of upstream determinants of depression is most likely to be enacted through public health approaches. Public health efforts to change communities and other contexts that shape health and to enact policies that modify social determinants of health require a skill set in epidemiology, economics and public policy that differs in fundamental ways from the skills that are the focus of mental health training.”

Collectively, the three goals at the heart of McLaughlin’s proposed agenda will require greater collaboration between mental health and public health professionals.

Reference:
McLaughlin, K.A. (2011). The public health impact of major depression: a call for interdisciplinary prevention efforts. Prevention Science, Forthcoming.