Chapter 1. Global priorities for addressing the burden of mental, neurological, and substance use disorders.

This volume of the third edition of the Disease Control Priorities (DCP) project addresses mental, neurological, and substance use (MNS) disorders. MNS disorders are a heterogeneous range of disorders that owe their origin to a complex array of genetic, biological, psychological, and social factors. Although many health systems deliver care for these disorders through separate channels, with an emphasis on specialist services in hospitals, the disorders have been grouped together in this volume to guide policy makers, particularly in low-resource settings, as they prioritize essential health care packages and delivery platforms (box 1.1). MNS disorders are grouped together because they share several important characteristics, notably: They all owe their symptoms and impairments to some degree of brain dysfunction. Social determinants play an important role in the etiology and symptom expression for many of these disorders (box 1.2). The disorders frequently co-occur in the same individual. Their impact on families and society is profound. They are strongly associated with stigma and discrimination. They often observe a chronic or relapsing course. They all share a pitifully inadequate response from health care systems in all countries, particularly in low- and middle-income countries (LMICs). Our grouping of MNS disorders is also consistent with programs intended to address their health burden, exemplified by the Mental Health Gap Action Programme (mhGAP) (WHO 2008), and with the goals of the third edition of Disease Control Priorities (DCP3) of synthesizing evidence and making recommendations across diverse health conditions. As we emphasize in this volume, these shared characteristics shape the response of countries in addressing the burden of MNS disorders. For example, a strong case is made for an integrated public health response to these conditions in all countries, but particularly in LMICs because of the paucity of specialist services in these settings. Such services have been the hallmark of the health system response to these conditions in high-income countries (HICs). DCP1 had only addressed a few MNS disorders: psychosis and bipolar disorder. DCP2 had focused on the cost-effectiveness of specific interventions for burdensome disorders, organized separately for mental disorders, neurological disorders, alcohol use disorders, illicit drug use disorders, and learning and developmental disabilities. In this third edition, we have considered interventions for five groups of disorders—adult mental disorders, child mental and developmental disorders, neurological disorders, alcohol use disorder, and illicit drug use such as opioid dependence—and suicide and self-harm-health outcomes strongly associated with MNS disorders. Within each group, we have prioritized conditions associated with high burden for which there is evidence in support of interventions that are cost-effective and scalable. Inevitably, such an approach does not address a significant number of conditions, for example, multiple sclerosis as a neurological disorder and anorexia nervosa as an adult mental disorder. However, the recommendations in this volume, particularly regarding the delivery of packages for care, could be extended to other conditions not expressly addressed. In addition, some important MNS disorders or concerns are covered in companion volumes of DCP3, notably, nicotine dependence, early childhood development, neurological infections, and stroke. This volume addresses four overall questions and themes (box 1.3): First, we address the question of why MNS disorders deserve prioritization by pointing to and reviewing the health and economic burden of disease attributable to MNS disorders. We build on the 2010 estimates of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD 2010) in two important ways: by examining trends in the burden over time, and by estimating the additional mortality attributable to these disorders. Second, we address the question of what by reviewing the evidence on the effectiveness of specific interventions for the prevention and treatment of a selection of MNS disorders. Third, we consider how and where these interventions can be appropriately implemented across a range of service delivery platforms. Fourth, we address the question of how much by examining the cost of scaling up cost-effective interventions and the case for enhanced service coverage and financial protection for MNS disorders. This chapter also considers how some countries have attempted to incorporate this body of evidence into scaled-up programs for MNS disorders. The chapter discusses lessons on barriers and strategies for how these will need to be addressed for successful scaling-up. The primary focus of the volume—and DCP3 as a whole—is on LMICs. We include HICs in the section on global disease burden, and we draw liberally on the concentration of available evidence on intervention effectiveness from these countries.