Substance use disorders and behavioral addictions
Exam items focus on counting DSM-5 criteria for severity, recognising withdrawal timelines, and choosing substitution therapy safely.
Core rules
- DSM-5 substance use disorder has eleven criteria; 2-3 mild, 4-5 moderate, 6 or more severe. Tolerance and withdrawal count, but caution is needed when the substance is taken as prescribed.
- Alcohol withdrawal timeline: tremor and autonomic hyperactivity at 6-24 hours, alcoholic hallucinosis at 12-24 hours, withdrawal seizures at 12-48 hours, delirium tremens at 48-96 hours. Benzodiazepines are the treatment of choice, guided by a scale such as CIWA-Ar; antipsychotics alone do not prevent seizures.
- Give parenteral thiamine before glucose in malnourished patients. Wernicke encephalopathy is the triad of ophthalmoplegia, ataxia and confusion; untreated it leads to Korsakoff syndrome.
- Opioid agonist therapy: methadone (full agonist) and buprenorphine (partial agonist, safer in overdose, can precipitate withdrawal if given too early). Naltrexone is an antagonist used for maintenance after detoxification and carries hepatotoxicity risk. Naloxone reverses overdose.
- Nicotine: varenicline, bupropion and nicotine replacement; combine counselling with pharmacotherapy.
- Behavioral addictions: gambling disorder is the only non-substance disorder in the DSM-5 chapter; internet gaming disorder sits in Section III pending further study.
Worked example
A 45-year-old man presents 36 hours after his last drink with tremor, sweating, pulse 118 and a CIWA-Ar score of 16. This is alcohol withdrawal at seizure-risk timing, so he needs a benzodiazepine (diazepam or lorazepam in liver disease), thiamine, fluids and electrolyte correction, not a standing antipsychotic.
Traps
Using antipsychotics as monotherapy in alcohol withdrawal; giving glucose before thiamine; starting buprenorphine while the patient is still opioid-intoxicated; forgetting that disulfiram requires abstinence and causes a reaction with alcohol-containing products.