Substance Use and Misuse

Millions of people worldwide suffer from addiction and related comorbidities. ^1,2 Given its association with high rates of mental and physical problems as well as premature mortality, ^{3 –6} substance misuse remains a significant global public health problem and a heavy burden for abusers and their families alike. In addition, methods of administration, including injection and some smoking practices, lead to greater risk of users contracting blood-borne diseases such as HIV, viral hepatitis, and subacute bacterial endocarditis. ⁷ Clearly, addiction is a multifaceted, frequently comorbid problem that cannot be reduced to compulsive substance use. In response to this challenge and to take into account such complexity, addiction research has evolved tremendously over the past few years. Many changes are currently taking place in the field of addiction from both an epidemiologic and clinical research perspective. This In Review represents a timely opportunity to provide psychiatrists and other clinicians with a glance at these new trends and research agenda. We also hope that it will contribute to bolstering a growing interest for substance use disorders within the mental health field.

The addiction research community has historically relied on American and European epidemiologic studies to identify and understand trends in substance use and misuse. Large-scale Canadian samples have recently generated critical national data and informed more refined and detailed descriptions of these trends in specific populations. Roy, Arruda, and collaborators present a review of Canadian epidemiologic data on substance misuse with a specific focus on newly identified phenomena. They highlight a number of results obtained over the past decade from longitudinal cohorts of street-based drug users, and they discuss the emergence of a prescription opioid use epidemic and its comorbid correlates. This article also looks into the highly prevalent but poorly investigated phenomenon of binge drug use. The authors pinpoint what could be a significant vector of risky behaviours and comorbidities and provide the basis for a complete research agenda that could significantly help to identify a new treatment target. Finally, Roy et al. establish critical emerging trends of mental health comorbidity among highly vulnerable populations of drug users in Canada. This endeavour reminds the field of psychiatry that addiction and “classic” mental health problems cannot be dissociated and that the accuracy of our understanding of psychiatric diagnoses, the impact of their symptoms, and their etiology may have to be reassessed in substance users.

Blaine and collaborators provide another fascinating example of the widened conception of addiction, which goes beyond substance use per se. Stress vulnerability and craving have been acknowledged as prominent features of addiction, and the latter has even been included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, criteria for substance use disorder. They are now known to be associated with a wealth of adverse outcomes such as higher rates of relapse even after prolonged periods of abstinence. A significant number of biological, neuroanatomic, psychologic, and environmental correlates of craving have been identified and are now better understood. Craving and stress have thus become key targets of addiction treatments, including pharmacotherapy and relapse prevention therapy. In this very thorough yet accessible article, Blaine and collaborators review the main findings pertaining to craving and stress vulnerability as critical features of alcohol dependence, and they underline their potential as innovative treatment targets to reduce the burden related to addictive disorders.

While these developments have made significant contributions to our understanding of addiction and its comorbidities, we are left with many challenges. An overhaul of current practices is undoubtedly required to have a concrete positive impact on the lives of substance abusers and their families. From a research perspective, the fast-changing substance use scene as well as the identification of myriad new treatment targets call for more cohesive, collaborative initiatives. The Canadian Institutes of Health Research have already responded to this task by launching the Canadian Research Initiative in Substance Misuse. This network of pan-Canadian nodes was designed not unlike the US-based Clinical Trial Network (from the National Institute on Drug Abuse) and is assembled of a group of researchers, substance users, family representatives, clinicians, stakeholders, and policy-makers. By regrouping research forces from across the country, the intention is that large clinical trials may be conducted faster, while the results can be used more effectively and rapidly to influence clinical practices. Although such initiatives take time to come into full effect, the potential to profoundly transform the field is promising if resources and a cohesive effort are sustained on a long-term basis.

From a clinical perspective, providers and policy-makers will have to be up to the task of changing current practices to confront the multifaceted problem that is addiction. For example, a limited number of specialized programs have been developed to address concurrent disorders across Canada. Our experience with building a joint addiction medicine and addiction psychiatry program at the Centre Hospitalier de l’Université de Montréal, in Montreal, has been both fascinating and very informative about the necessary next steps to prioritize. Such academic programs are crucial to providing specialized care, ensuring training leadership, and contributing to innovations through research initiatives. However, they cannot act alone in ensuring that all patients have access to appropriate care for addiction, mental health, and other physical conditions. Integrated treatment must occur at all levels of care, from the family doctor or the psychologist’s office, to the needle-exchange programs, and, undoubtedly, to the psychiatric clinics. The past 2 decades have provided more than enough evidence to understand that addiction is a distressing problem that affects behaviours, social functioning, and mental and physical health. It is now time to ensure that our approach to help people suffering from addiction reflects this understanding that can no longer be ignored.