What is clear, is that interventions that fail to appreciate the role the causal role of psychological experience in physical and mental health as well as the reciprocal relationship between physical and mental health miss substantial opportunities in the prevention and the amelioration of chronic conditions. Moreover, the biases in treatment towards physical illness in the health service is inefficient given that high degree of co-morbidity with mental health conditions because we know that mental ill health affects adherence to treatments and prognosis. DiMatteo, Leeper and Croghan (2000) showed that people with depression were three times less likely to adhere to treatment regimens that people without depression. This commissioning bias also ignores the evidence that health-related quality of life is significantly lower for depressed patients than for people with physical health conditions for example, asthma, arthritis, and diabetes [Moussavi S, Chatterji S, Verdes E, Tandon A, Patel V, et al. (2007)] 

The global context

Our healthcare systems are struggling to meet increasing demand for care due to the increasing burden of NCDs \citep{Guzman-Castillo2017} (also see Fig \ref{535015}). In 2017, seventy nine percent of years lived with disability (YLDs) globally are attribtuable NCDs \cite{hub}. Furthermore, prominent NCD conditions include depression and anxiety, common mental disorders associated with 5.05% and 3.18% of global YLDs in 2017, respectively (Fig \ref{535015}). Unfortunately, healthcare systems are still driven by the medical model, which focuses on returning patients to good health (cure), rather than condition management.
Treatment gap and treatment lag (Patel et al., 2010) \citep{Wang2004} are major obstacles to be overcome. The treatment gap relates to the numbers of people who need treatment that are not receiving it, while treatment lag refers to the amount of time taken to receive mental health treatment when it does exist. The treatment gap for mental disorders has been estimated to exceed 50% in all countries of the world, and to reach 90% in those with less resources (Patel et al., 2010). The treatment lag has been estimated to be longer than a decade (Wang, Berglund, Olfson, & Kessler, 2004). These considerations have major societal and economic implications for improving wellbeing of current and future generations.