Substance Use Disorders and Addictive Behaviours
Core concepts
Tolerance, withdrawal, craving, loss of control, salience, continued use despite harm, and social/occupational consequences. Know intoxication and withdrawal syndromes: alcohol (tremor, seizures, delirium tremens), opioids, benzodiazepines, stimulants, cannabis, hallucinogens, and novel psychoactive substances.
Assessment and screening
AUDIT-C, CAGE, and structured withdrawal scales. Take a non-judgemental history, assess motivation (stages of change), and screen for psychiatric comorbidity and suicide risk. Thiamine before glucose in malnourished patients to prevent Wernicke's encephalopathy.
Treatment
Brief interventions and motivational interviewing; detoxification with benzodiazepines for alcohol and opioids substitution; naltrexone, acamprosate, disulfiram; opioid substitution therapy; nicotine replacement and varenicline. Psychosocial: CBT, contingency management, 12-step facilitation.
Traps
Missing withdrawal delirium; attributing psychotic symptoms to schizophrenia when substances are involved; forgetting that benzodiazepine withdrawal can be life-threatening; assuming abstinence is the only valid goal.
Worked rule of thumb
In any patient with alcohol dependence, give parenteral thiamine before carbohydrate loading. If withdrawal includes confusion, autonomic instability and hallucinations, treat as delirium tremens in a medical setting.