Mental disorder: a public health problem stuck in an individual-level brain disease perspective?
Authors: Jim van Os
Journal: World Psychiatry (2015)

K. Wahlbeck provides a range of cogent arguments supporting the view that the natural perspective for mental health is in the realm of public health. In reality, however, the perspective of public health is not dominant in academic psychiatry or in the way mental health services are organized. The dominant model in academic psychiatry is embedded in an individual-level perspective of brain disease, although there is considerable debate as to how successful this dominant approach has been 1. A student wanting to find out about psychiatry may get the impression that two languages are spoken in mental health: a public health one, taking into account the natural perspectives of high prevalence, graded trajectories from health to illness, social determinants, empowerment and self-determination, resilience, positive mental health and prevention; and a biomedical one, focusing on illness and diagnostic labels, brain disease, animal research, genetic liability, biological determinants and pharmacological interventions. The existence of two languages in mental health research is one of the explanations of the limited crosstalk between areas distributed over the public health and natural sciences, even though the application of scientific paradigms to mental health research, including those derived from neuroscience, psychiatry, public health, epidemiology, social science, sociology, psychology and philosophy, has expanded exponentially. In other words, research in mental health has expanded exponentially, but in widely different directions, showing signs of increasing fragmentation rather than integration. If natural science and public health are to join forces, this will have to be at the level of research endeavours in which the results are interpreted on the basis of a common language. There are some pointers as to which elements may be used to construct a common language. First, research in public health highlights powerful effects of the social environment on onset and persistence of syndromes of mental ill-health, the existence of vulnerable and resilient subgroups, and possible cognitive, neural and behavioural mediation of environmental effects. Second, research in psychology and psychiatry indicates that most mental disorders as defined in DSM and ICD represent quantitative deviation from health. Third, research in basic population genetics highlights the importance of (epi)genetic variation in terms of short-term and long-term adaptation to the social environment. Fourth, research in social neuroscience is highlighting the role of the brain in enabling man to navigate the social world and is building models of the way in which our current context – which includes both the social environment and our internal states and traits – impacts on how we attach meaning to social cues. There is increasing interest in the role of culture in these processes, for example how cultural variation may impact on social cognition and the process of empowerment in relation to one's circumstances. The above four elements indicate that genetic variation and neural processes form the biological roots of human sociality, resulting in the mutual constitution of cultures and selves; they also suggest that health and illness result from complex interactions between the physical, cultural, and social environments. Thus, a common theme emerges linking deviation from mental health, genetic variation and neural function, which can be formulated as dynamic adaptation to the individual-level and wider social environment. Dynamic adaptation to the environment may constitute a point of entry towards a common language in mental health research, linking social and natural sciences. However, this perspective contrasts with the current practice of research in biological psychiatry, which typically involves comparisons between a group of severely ill patients constrained by DSM or ICD criteria of disorder, and healthy, or "super-healthy", controls on static measures of, for example, allelic frequency or cortical thickness. In other words, the role of genetic and neural variables in dynamic adaptation to the social world, including at the level of intentionality and meaning, is typically not taken into account. Public health approaches in mental health research can be introduced focusing on genetics, neuroimaging and animal models, using the perspective of dynamic adaptation to the environment. For example, what potentially links the different approaches in mental health research is the level at which social and cultural influences are studied, and how these might interact with each other. Public health research is of particular interest in the area of how the wider social environment may impact on risk for and resilience against mental disorders. Examples of such contextual variables are social cohesion and trust, social capital, social integration, ethnic density, population density, social divide or social inequality. Research has shown that these types of contextual variables are strongly associated with mental outcomes (risk and resilience), and interact with individual-level characteristics (e.g., individual-level ethnic group and ethnic density). As there is a paucity in cross-discipline approaches, this type of research has yielded little in terms of causality, biological and psychological mediators and moderators, and developmental pathways. It is reasonable to assume that the impact of the wider social environment will be mediated by individual-level cognitive and (cross-species) biological factors and that it will be moderated by the same factors. It is clear that a rich potential exists for collaboration between public health scientists on the one hand, and mental health and neuroscience researchers on the other. While it may be attractive to align cross-species behavioural research paradigms, resulting in a multilevel perspective on underlying neural mechanisms, there is an additional need to co-align and co-evaluate this work with "mental" paradigms, for example from experimental psychology. A good starting point to bring together research on behavioural, neural and cognitive mechanisms around a single paradigm is to study the impact of a certain environmental exposure (at the level of repeated within-person momentary micro-environment, the individual level, or the contextual level of the wider social environment) on mental, behavioural, neural, cellular and molecular outcomes in a single observational or experimental "social" paradigm, taking into account moderation of environmental influence by genetic factors. For example, childhood adversity and having a minority position in society are important social risk factors with powerful effects that can be described in terms of developmental mental, molecular, cellular, neural circuit, cognitive and behavioural effects, in association with evidence of moderation by genetic variation. Bringing these together in a single collaborative research effort, linking the different mechanisms, will make it possible to enrich the outcome of individual research efforts synergistically.