Page - 163 - in Biodiversity and Health in the Face of Climate Change

163 Yet another definitional issue is where to draw the line between a risk factor and mental health itself. Risk factors may act as mediators, with a high risk of increasing the likelihood of poor mental health or a specific mental disorder. However, if some- thing is not to be considered a risk factor, but a specific form of poor mental health, then it becomes questionable to use it as a mediator at the same time.1 A case in point is chronic stress. Whereas some authors suggest that chronic stress may cause poor mental (and physical) health (e.g. Marin et  al. 2011), others see it as an expres- sion of poor mental health in itself (e.g. Aszatalos et  al. 2009).2 8.1.3 Linking Biodiversity to  Mental Health: Research Questions and  Conceptual Model Methodological choices in doing research depend not only on the definition of the key concepts, but also on the question that the research is intended to answer. In the section on biodiversity, it was stated that biodiversity is predominantly an ecologi- cal concept, not evolved from theoretical notions on how contact with nature is thought to positively impact mental health. The section ended suggesting that a relevant first research question might be whether or not nature with a high level of biodiversity can go together with high mental health benefits resulting from contact with that same nature. This issue of compatibility does not yet look into possible causal relationships, whether the one leads to the other or not. However, the ques- tion, under which conditions a high level of biodiversity may go together with high mental health benefits, already necessitates insight into which characteristics of nature are important with regard to mental health. Of course, the level of biodiver- sity present within a certain amount of nature might still be one of those characteristics. With regard to the level of biodiversity of a natural area actually being an instru- mental factor in mental health promotion, it may be that the sheer (sustained) exis- tence of a certain (highly biodiverse) natural area engenders mental health benefits, even though one never visits or otherwise comes in direct contact with it (van den Born et  al. 2018). However, most theories focus on pathways requiring some sort of sensory contact with that nature for it to exert its positive influence on mental health (Markevych et  al. 2017). Furthermore, more contact is usually assumed to lead to greater benefits, at least up to a certain point (Shanahan et  al. 2016). This is likely to have consequences for what one may want to measure. In the remainder of this chapter, we limit ourselves to the latter type of pathways, requiring direct contact. 1 It still can be used as a predictor of overall mental health, but such an analysis may also be inter- preted as showing how important a component it is of overall mental health, more than as a causal factor. 2 A similar argument can be made with regard to being seriously overweight and having bad physi- cal health. 8 Biodiversity in  the  Context of  ‘Biodiversity  – Mental Health’ Research