Chapter 11: Substance-Related Disorders

The epidemiological landscape is presented through global prevalence data and cultural variations, establishing the substantial public health implications of these disorders across populations. Central to understanding addiction is the neurobiological framework, which emphasizes the brain's reward system, dopaminergic signaling, the mechanisms underlying tolerance development, withdrawal syndrome generation, and the progressive transition from voluntary consumption to compulsive substance-seeking behavior. The chapter systematically addresses major substance classes including alcohol, opioids, stimulants such as cocaine and methamphetamine, cannabis, hallucinogens, inhalants, nicotine, sedative-hypnotics, and misused prescription medications, detailing their acute physiological effects, characteristic withdrawal presentations, acute toxicities, and associated psychiatric complications. Diagnostic frameworks are explored through comparison of DSM-5 and ICD-10/11 systems, highlighting the conceptual shift toward dimensional substance use disorder diagnosis rather than categorical abuse-dependence distinctions. The chapter examines high rates of comorbidity with major depression, anxiety disorders, psychotic disorders, and personality pathology, explaining how concurrent psychiatric conditions complicate treatment outcomes and prognosis. Evidence-based treatment modalities are thoroughly reviewed, encompassing medical detoxification protocols, pharmacological interventions including methadone and buprenorphine maintenance, opioid antagonist therapy with naltrexone, alcohol-specific agents like acamprosate, and psychosocial interventions such as motivational interviewing, cognitive-behavioral therapy, and contingency management approaches. Specialized treatment strategies including twelve-step facilitation, relapse prevention frameworks, harm reduction philosophies, and integrated dual-diagnosis care models are discussed. The chapter concludes by addressing sociocultural dimensions including stigma reduction, treatment access disparities, family and community impact, and emerging therapeutic innovations such as neuromodulation techniques and pharmacogenetic approaches to treatment selection.