Units of alcohol

In the assessment of alcohol consumption it is useful to have a standardized measure of alcohol. It has been found that the amount (mass) of alcohol contained in a standard measure of spirits, in a standard glass of sherry or fortified wine, a standard glass of table wine, and in one half-pint of beer or lager of standard strength (3–3.5% by volume) is approximately the same, at 8–10 g. This amount is known as a unit of alcohol (Figure 7.1). Note that some (European continental) lagers can be as strong as 5–6% by volume, and some wines can be as strong as 17% (or even higher) by volume; the figures given in Figure 7.1 have to be adjusted accordingly in such cases. Also, although Figure 7.1 considers 25 mL to be a standard measure for spirits, some public houses and bars now use larger ‘standard’ measures for spirits, so that the number of units of alcohol is correspondingly higher.

Figure 7.1 • Alcoholic beverages and units of alcohol.

Levels of consumption

The Royal College of Physicians has defined low-risk levels of alcohol consumption as being up to 21 units per week for men and up to 14 units per week for women (Figure 7.2). This amount of alcohol should not be consumed in one go, and alcohol should not be consumed every day, for these levels to apply.

Figure 7.2 • Levels of alcohol consumption.

Alcohol consumption in greater amounts constitutes excessive consumption and carries a much greater risk of developing alcohol-related disabilities and alcohol dependence. The definitions of increasing hazard and dangerous levels of alcohol consumption are also shown in Figure 7.2.

Abstinence or minimal alcohol consumption is recommended in pregnancy, as otherwise there is a risk of the development of fetal alcohol syndrome (see below).

Physical (medical) morbidity

Excessive alcohol consumption is associated with an increased mortality, with approximately one-fifth of men admitted to general medical wards having been found to suffer from problem drinking (defined below). Gastrointestinal disorders are a common consequence of excessive alcohol consumption and include:

Malnutrition occurs mainly as a result of poor food intake, particularly of protein and the B vitamins. Other causes include the gastrointestinal disorders just mentioned.

Hepatic damage takes place chronologically in the following order:

Both acute pancreatitis and, following years of excessive alcohol consumption, chronic pancreatitis can occur.

Cardiovascular system changes include hypertension and cardiac arrhythmias, particularly after binge drinking.

Haematological complications include:

Cancer of the oropharynx, oesophagus, pancreas, liver and lungs is increased in incidence.

Excessive alcohol consumption in pregnancy can lead to permanent fetal damage. The clinical features of the consequent presentation of the fetal alcohol syndrome following birth are shown in Figure 7.3.

Figure 7.3 • Fetal alcohol syndrome in a child whose mother consumed excess alcohol during pregnancy.

Accidents and trauma may result from alcohol consumption. These include:

There is an increased risk of infections such as tuberculosis, particularly in homeless people who drink heavily.

Nerve and muscle disorders, some of which are potentially reversible in the early stages if alcohol consumption is stopped, include:

Psychiatric morbidity

Alcohol affects the mood of the drinker. Excessive alcohol consumption may initially take place because the drinker wishes to relieve disagreeable mood states, such as anxiety and low mood. However, chronic heavy drinking can itself produce such unpleasant states. Indeed, the rate of suicide is at least 50 times greater in such drinkers than in the general population.

Alcohol also affects the personality of the drinker, who may initially drink to achieve such superficial effects as appearing more sociable and sexually desirable. However, the effects of chronic heavy drinking on personality are often negative, causing boastfulness, embarrassing speech and actions and offensiveness. With persistent heavy drinking personality deterioration occurs, which may simulate a personality disorder (see Chapter 15).

Intoxication frequently leads to episodes of short-term amnesia or blackouts. For example, the events that occurred during heavy drinking the night before, while the subject was still conscious, are no longer recalled the following morning. This phenomenon does not necessarily imply chronic alcohol use; it may occur after just one bout of heavy drinking, and indeed is estimated to have been experienced by 15–20% of those who drink.

In chronic heavy drinkers, a fall in the blood alcohol concentration leads to withdrawal symptoms (see below). These include delirium tremens or DTs. The features of delirium have been described in Chapter 6. Another important withdrawal symptom is withdrawal fits, which may occur within 48 hours of stopping drinking.

A rarer psychiatric disorder caused by chronic alcohol intake is alcoholic hallucinosis, which is characterized by the occurrence of auditory hallucinations in clear consciousness. These may be in the form of noises or voices uttering derogatory remarks and threats; they may sometimes be in the third person and describe the patient’s actions. Alcoholic hallucinosis should therefore be considered in the differential diagnosis of schizophrenia when there is a history of chronic alcohol consumption.

A number of psychosexual disorders can result from taking alcohol. Although it reduces inhibitions and may increase the desire for sexual intercourse, in men intoxication leads to erectile impotence and delayed ejaculation. Chronic heavy drinking in men can cause loss of libido, reduction in the size of the testes and penis, loss of body hair and gynaecomastia, whereas in women it can lead to menstrual cycle abnormalities, loss of breast tissue and vaginal dryness.

Chronic heavy drinking is one cause of pathological (delusional) jealousy (see Chapter 8). Alcohol is also a cause of fugue states (see Chapter 11).

Heavy drinking is often associated with gambling and the use of other psychoactive substances. It can also be a cause of dementia (see Chapter 6).

The most common cause in the Western world of the amnesic or Korsakov’s syndrome is thiamine (vitamin B₁) deficiency secondary to alcohol abuse. Alcohol-induced amnesic syndrome is frequently preceded by Wernicke’s encephalopathy. This is also caused by severe thiamine deficiency, which, in turn, is usually caused by alcohol abuse in Western countries, when the term alcoholic encephalopathy may also be used. Other causes include: lesions of the stomach (e.g. gastric carcinoma), duodenum or jejunum, causing malabsorption; hyperemesis; and starvation. The most important clinical features of Wernicke’s encephalopathy are:

In its early stages, Wernicke’s encephalopathy may be reversible through abstinence and the administration of high doses of thiamine; the amnesic syndrome is irreversible. As the latter may emerge from Wernicke’s encephalopathy in chronic alcohol abuse, the term Wernicke–Korsakov syndrome is sometimes used.

Social morbidity

The social costs of excessive alcohol consumption are very high, and include the following: