Write a short note on alcohol misuse and its neuropsychiatric manifestations.

Definitions

• Hazardous drinking: a level of consumption likely to cause harm if continued.
• Harmful drinking: consumption already causing physical or psychological damage.
• Alcohol dependence: a cluster of compulsion to drink, impaired control, tolerance, withdrawal on cessation, primacy of drinking over other activities, and persistence despite harm.

One unit is 8 g of ethanol; a standard peg (30 mL of spirits) is roughly 1.2 units.

Screening

• CAGE questionnaire — Cut down, Annoyed by criticism, Guilty about drinking, Eye-opener in the morning. Two or more positive answers suggest a problem.
• AUDIT — a 10-item WHO instrument, more sensitive for hazardous drinking.
• Laboratory markers: raised gamma-glutamyl transferase, raised MCV, AST:ALT ratio greater than 2:1, raised carbohydrate-deficient transferrin.

Neuropsychiatric Manifestations

Acute

• Intoxication — disinhibition, ataxia, dysarthria, nystagmus, progressing to stupor, coma and respiratory depression.
• Pathological intoxication — marked aggression after a small quantity.
• Blackouts — anterograde amnesia for events during intoxication, an early marker of harmful use.
• Withdrawal syndrome — tremor, hallucinosis, seizures and delirium tremens (see the withdrawal note).

Thiamine-related

• Wernicke's encephalopathy — the triad of confusion, ophthalmoplegia (lateral rectus palsy, nystagmus) and ataxia. The full triad is present in only about a third of cases, so treat on suspicion. Lesions occur in the mammillary bodies, periaqueductal grey and thalamus.
• Korsakoff psychosis — the chronic irreversible sequel: profound anterograde amnesia with confabulation and relatively preserved other cognitive functions.

Chronic neurological

• Cerebellar degeneration — affecting the anterior superior vermis, producing a broad-based gait ataxia with relative sparing of the arms and speech.
• Peripheral neuropathy — symmetrical, sensorimotor, painful, length-dependent; due to thiamine deficiency and direct toxicity.
• Central pontine myelinolysis — from over-rapid correction of hyponatraemia in a malnourished alcoholic; causes quadriparesis and pseudobulbar palsy.
• Marchiafava-Bignami disease — demyelination of the corpus callosum, with dementia, seizures and interhemispheric disconnection.
• Alcoholic dementia, cerebral atrophy, and increased risk of subdural haematoma from falls.
• Hepatic encephalopathy in established cirrhosis.

Psychiatric

Depression (usually secondary and improving with abstinence), anxiety, alcoholic hallucinosis (auditory hallucinations in clear consciousness, with insight preserved), morbid jealousy (Othello syndrome), suicide — markedly increased risk — and family and social disintegration.

Management

• Detoxification — benzodiazepine taper (chlordiazepoxide; lorazepam in liver disease) with thiamine and multivitamin supplementation, electrolyte correction, and treatment of intercurrent illness.
• Relapse prevention:
• Disulfiram — aldehyde dehydrogenase inhibitor causing a highly unpleasant reaction with alcohol; requires a motivated, supervised patient.
• Acamprosate — modulates glutamate transmission, reducing craving.
• Naltrexone — opioid antagonist reducing the rewarding effect of alcohol.
• Psychosocial — motivational interviewing, brief interventions, cognitive behavioural therapy, Alcoholics Anonymous and family involvement. Brief intervention in the general hospital setting is effective and underused.
• Treat the physical consequences — liver disease, pancreatitis, cardiomyopathy, gastritis, anaemia and malnutrition.