Addiction—25 Years Later
In its first publishing year, HRP published five articles on addiction that were emblematic of the state of the field at that time,2–6 including: evidence for adaptations to chronic drug administration in the brain’s ventral tegmental area and nucleus accumbens;2 clinical and preclinical studies of buprenorphine treatment of opioid and cocaine dependence;3 the role of psychotherapy in the treatment of substance use disorders;4 emerging evidence of gender differences in alcohol-related disorders;5 and the importance of treating co-occurring psychiatric disorders.6 There has been a rapid acceleration of new knowledge in each of these areas over the last two decades.
Basic and translational research has expanded our understanding of the reward circuitry underlying addiction, including brain circuits that mediate substance-induced reward pathways, stress-related changes during withdrawal, and craving and compulsion.7 These interconnected neural circuits are disrupted through the chronic use of substances, and affect the pathways of reward, learning, and control. A convergence of data over the past two decades also demonstrates that 40% to 60% of the risk for addiction is conferred by genetics. The array of gene variants implicated in the development of SUDs grows each year. In addition, in the past decade new research has highlighted epigenetic mechanisms that can switch on genes implicated in the development of addiction. Early childhood trauma may be a particularly powerful environmental stressor that produces potentially heritable epigenetic changes that confer greater risk for addiction in later life. To provide even greater understanding of the developmental risks for SUDs, a new ten-year longitudinal study, the Adolescent Brain Cognitive Development study, was launched by the National Institutes of Health in 2016 to investigate the effects of substance use at critical stages of adolescent brain development.
Parallel to discoveries in the areas of neuroscience and genetics, treatment research has expanded the evidence base for effective medications and behavioral treatments across different substances of abuse and levels of SUD severity.