Psychiatry High-Yield: Substance Use Disorders
Modern psychiatry categorizes “addiction” and “dependence” under the unified diagnosis of Substance Use Disorder (SUD), defined by a problematic pattern of use leading to clinically significant impairment or distress.
Key Clinical Concepts
| Term | Core Meaning |
|---|---|
| Tolerance | Reduced effect of the substance with continued use, requiring higher doses. |
| Physical Dependence | Occurrence of withdrawal symptoms upon cessation of the substance. |
| Psychological Dependence | Compulsive seeking behavior; using the substance to cope with emotional states. |
| Addiction | Chronic, relapsing disorder with loss of control, despite negative consequences. |
Neurobiological Basis
The common pathway for most addictive substances is the Mesolimbic Dopamine Pathway (the “reward pathway”), involving the Nucleus Accumbens and the Ventral Tegmental Area (VTA).
High-Yield Exam Pearls:
- Withdrawal States: CNS depressants (Alcohol, Benzodiazepines) have life-threatening withdrawal; CNS stimulants (Cocaine, Amphetamines) generally have non-life-threatening but psychologically distressing withdrawal.
- Opioid Overdose: The clinical triad is Coma, Miosis (pinpoint pupils), and Respiratory Depression. The immediate antidote is Naloxone.
- Relapse Prevention: Often involves a combination of long-term psychosocial therapy (CBT, 12-step programs) and pharmacological maintenance (e.g., Methadone or Buprenorphine for opioid dependence).