THE moderate consumption of alcohol is not harmful to most adults. However, social drinking in some individuals can lead to heavier consumption, which can cause health problems. Alcohol misuse can result in alcohol dependence or alcohol abuse.
The World Health Organisation (WHO) defines alcohol dependence (alcoholism) as a medical condition if three or more of the following features have been experienced or exhibited in the past year:
WHO also defines the related concept of abuse. This refers to a pattern of alcohol consumption that exposes the individual to the risk of harmful consequences, which may be damaging to physical or mental health or both; or they may include social consequences to the individual or others e.g. failure to fulfil school or work response responsibilities, drinking when driving or operating heavy equipment.
The pattern of drinking may result in risks. Some people drink in large amounts on certain occasions but no more than the recommended amounts on a regular, weekly basis. Others drink heavily on a regular basis and since they have become tolerant, may not have marked impairment despite the high blood alcohol levels.
The harm may be either physical e.g. liver damage or mental e.g. depression secondary to drinking or both. An individual’s susceptibility to alcohol-related harm varies considerably e.g. only about 20%-30% will develop liver cirrhosis among chronic abusers of alcohol. The factors that determine susceptibility to harm are yet to be fully clarified but genetic, constitutional and environmental factors are important.
Although alcoholism is different from alcohol abuse, the effects are experienced by both categories of alcohol misuse.
Accidents and injuries
Alcohol is a major factor in accidents and injuries i.e. road traffic, work and home. It is also a major factor in assault and suicide. Alcohol-related accidents and injuries are associated with greater morbidity and mortality than all other alcohol-related conditions.
Alcohol affects the gastrointestinal tract. Gastro-oesophageal reflux (oesophagitis) may develop in chronic alcohol misuse. There is a strong association between cancer of the oesophagus and alcohol misuse, especially in heavy smokers. Both acute and chronic gastritis may develop; the former with nausea, vomiting, epigastric pain and occasionally acute bleeding and the latter with no symptoms or non-specific gut symptoms.
The incidence of helicobacter pylori infection is lower in those who consume alcohol. Diarrhoea may occur with acute and chronic alcohol misuse.
The consumption of more than 7.5 units per day in men and five units per day in women increases the risk of alcohol-related liver conditions, which include fatty change, hepatitis, cirrhosis and cancer. However, only about 20%-30% of those who misuse alcohol develop cirrhosis and of these, about 15% will develop cancer.
The daily intake of 1-3 units per day protects middle-aged men against coronary heart disease. There is less information about women but daily intakes of 1-2 units protect against coronary artery disease in post-menopausal women.
Alcohol misuse can also affect the cardiovascular system. The blood pressure, both systolic and diastolic, is increased but the increases reverse when the alcohol consumption ceases. Alcohol-related heart muscle disease (cardiomyopathy) may occur in some individuals who consume more than 7.5 units per day for at least 10 years.
The cardiac changes in those with the sub-clinical condition will reverse entirely when alcohol consumption ceases. In those who continue to drink, death can occur within two-four years of the onset of heart failure.
The acute and chronic misuse of alcohol increases the risk of strokes. There is also an increased risk of head injuries resulting in haematomas adjacent to the brain.
Central nervous system
The central and peripheral nervous systems may also be affected by alcohol misuse. There may be impairment of cognition, amnesia and dementia. The brain may shrink with reduction in the volume of the white matter. The changes in the mental state and the brain may reverse to a variable degree when alcohol consumption is stopped for a long period of time. There may be focal peripheral nerve changes usually because of nerve compression when sleeping. Chronic misuse may also affect the nerves in the lower limbs especially when associated with thiamine deficiency.
Bone fractures may result from accidents or injuries. The increased incidence of osteoporosis in alcohol misuse is considered to be due to its effect on bone re-modeling and mineralisation but other factors like cigarette smoking and nutritional deficiencies may be associated factors.
Alcohol misuse may affect sexual and reproductive function in men and women. It can also affect fertility significantly even if taken in moderate amounts.
The regular consumption of alcohol by pregnant women may potentially harm the developing foetus, especially when consumed in the first three months of pregnancy.
The foetal alcohol syndrome has the features of growth retardation during pregnancy and after birth; central nervous system abnormalities like mental retardation, poor tone, incoordination; head and face abnormalities like drooping upper eyelids, thin upper lips, underdeveloped lower jaw; and other associated abnormalities e.g. congenital abnormalities of the eyes, ears, mouth, and cardiovascular, genitourinary and skeletal systems.
The medical advice to pregnant women is to abstain from alcohol in the first three months of pregnancy and to limit their consumption to one-two units once or twice a week for the rest of the pregnancy.
There is a strong association between cancers of the mouth, pharynx, larynx and oesophagus and chronic alcohol misuse, especially when the individuals are smokers. About 15% of those with liver cirrhosis develop liver cancer but alcohol misuse by itself is not a factor in the development of liver cancer. Alcohol is also a risk factor in breast cancer.
The Doctor Says now appears in Wednesday’s health pages.
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