## Neurochemistry of Alcohol Withdrawal **Key Point:** Alcohol withdrawal results from a sudden loss of alcohol's depressant effect on the central nervous system, leading to a characteristic pattern of neurochemical imbalance. ### Mechanism of Alcohol Dependence Chronic alcohol use causes: 1. **Downregulation of GABA~A~ receptors** — alcohol potentiates GABAergic inhibition; chronic use leads to compensatory receptor loss 2. **Upregulation of NMDA glutamate receptors** — alcohol inhibits glutamatergic excitation; chronic use leads to increased receptor expression ### Withdrawal Syndrome Pathophysiology When alcohol is suddenly removed: - **Loss of GABAergic inhibition** → reduced inhibitory tone - **Unopposed glutamatergic excitation** → hyperexcitability - This imbalance manifests as tremor, autonomic hyperactivity, seizures, and delirium tremens **High-Yield:** The GABA-glutamate imbalance is the cornerstone of alcohol withdrawal pathophysiology and explains why benzodiazepines (GABA agonists) are the first-line treatment. ### Clinical Correlation **Clinical Pearl:** Benzodiazepines work in withdrawal by: - Enhancing residual GABAergic function - Reducing glutamatergic excitotoxicity - Preventing seizures and delirium ### Why Other Systems Are Secondary | System | Role in Withdrawal | |--------|--------------------| | Dopamine | Not primary; may contribute to dysphoria but not the acute withdrawal syndrome | | Serotonin | Involved in mood but not the acute hyperexcitable state | | Acetylcholine | Not the primary mechanism; anticholinergics are not first-line | [cite:Harrison 21e Ch 474]
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