Alcohol and the nervous system

Alcohol is an available, legal, and frequently used drug in our society. However, its misuse and toxic effects are estimated to cost the British National Health Service £160 million each year in treatment costs. It is estimated that 28 000 people die each year in the UK as a result of their alcohol consumption.1 Alcohol’s associated morbidity impacts greatly on the work of the neurologist.

DETECTION OF ALCOHOL MISUSE

Approximately 25% of male medical admissions may be regarded as problem drinkers, with the group at highest risk being young male patients admitted to medical or orthopaedic wards.2

One of the key messages of this article must be to always ask patients about their alcohol use. This needs to be routinely documented in notes, perhaps most usefully with a full drug use history. People may minimise their alcohol use, so tact is necessary. Table 1 contains a list of questions that may be helpful; clearly it is important to get your own routine and to be guided by what the patient is able to tell you at that time. Relatives may also provide enlightening and not always corroborative histories.

ALCOHOL AT A NEUROTRANSMITTER LEVEL

Alcohol’s central nervous system (CNS) effects are mediated through actions on a variety of neurotransmitters. There is a complex interplay between excitatory and inhibitory systems (table 2). The numerous transmitters involved in alcohol’s action explain its diverse effects and the large number of drug interactions with both prescribed and illicit drugs.

ACUTE INTOXICATION

Many practitioners reading this article will be aware on both a personal and occupational level of the effects of acute intoxication. Blood alcohol concentrations reflect rate of intake, degree of tolerance, and the simultaneous effects of other drugs.

Extreme intoxication (> 300 mg/100 ml) leads to increasing drowsiness and then coma, with depressed tendon reflexes, hypotension, hypothermia, …