Public mental health: a call to action

K. Wahlbeck (1) convincingly argues that the prominent role of social factors in wellbeing and mental health is supported by overwhelming evidence. He states that a series of studies have shown how evidence-based programs to prevent mental disorders can be translated into everyday practice. However, he cautions that there is a lack of action in the most affluent countries, while there is an even wider gap between possible ways of intervention and current funding in the less affluent ones. Furthermore, he emphasizes the need for interdisciplinary research to broaden the theory-base of programs aimed at the promotion of public mental health. Let us briefly examine these arguments. There is indeed an abundance of studies showing an association between poverty and social exclusion on the one hand, and poor mental health on the other (2,3). However, correlation is not causation, and it may be argued that variables not detected in these studies – such as unknown familial influences including environmental and (epi-)genetic factors – may explain the observed correlations. But they either cannot be easily targeted (such as unknown familial factors) or are not even amenable to social interventions (such as genetic factors). Against such therapeutic nihilism, two arguments can be raised. First, a series of animal experiments and human studies have shown that social stress factors, particularly exclusion, stigmatization and discrimination, directly impact on the neurobiological correlates of mental disorders, impair cognitive capacities and promote aggression, drug intake and negative mood states (4,5). Indeed, even fluid IQ as a measure of complex cognitive capacities has been associated with variation in dopaminergic neurotransmission, which in turn is strongly affected by stress exposure (6-8). Second, most twin research has relied on the (controversial) assumption that gene-gene interactions are only additive and cannot exponentially increase similarity (e.g., when variation in multiple genes increases neurotransmitter synthesis and at the same time decreases both reuptake and metabolism). On the other hand, the “equal environment” assumption on which most twin studies are based does not differentially capture complex genotype-phenotype interactions. We caution that both supraadditive genetic effects as well as the presence of complex genotype-phenotype interactions could lead to an overestimation of genetic effects, which could in turn override environmental effects in twin study designs that assume only additive interactions (9). Hence, the current absence of evidence for environmental effects in many twin studies is not evidence of absence. Moreover, there is emerging evidence that the effects of genetic variation on behavioral phenotypes are amenable to targeted behavioral interventions, such as cognitive training (10). These considerations call for study designs that look at complex genotype-phenotype interactions and assess not only genetic but also epigenetic effects (11). With respect to Wahlbeck's argument that insufficient funds are spent on preventive programs in affluent countries and that there is a wide gap between available funds and social needs in the less affluent ones, one can only but agree and call for direct action. Epidemiological studies suggest that mental disorders impose a huge burden on individuals and their families, which is further augmented by social exclusion and stigmatization (12,13). It may be exactly due to this persisting stigma that, in spite of good evidence for the effectiveness of preventive programs, even rich countries do not provide sufficient funds. For those countries that are less affluent, some tough choices have to be made: it may be less helpful to promote hospital care if there is a lack of social consultation, as we experienced in Afghanistan and Mali, while educating social workers, nurses and general practitioners may have to take priority (14,15). Wahlbeck calls for interdisciplinary research to promote the theory basis of public health. Indeed, we strongly agree and suggest that both quantitative and qualitative research has its place in this respect. While animal experiments, longitudinal studies and epidemiological data can provide a quantitative account of the interaction of social and individual factors contributing to mental health and distress, qualitative studies can generate new lines of research and explore what a given situation really means for patients and their relatives as well as the general population. Indeed, neuroscience has turned social (16) and it is time for epidemiology and social psychiatry to embrace multi-level approaches to mental health and to put viable programs into practice.