Most adult readers will be familiar with alcohol in some way or another and will probably know a certain amount about the damage it can do in the long run. However, having read this far, most will already have the words 'liver damage' on the tip of their tongue, and so this Entry aims to point out that the effects of long-term alcohol abuse can be more far reaching than the average person would expect. While the following effects are all caused by chronic alcohol abuse, the exact degree of drinking required to precipitate a particular disease varies between individuals. Needless to say, the greater the alcohol intake, the greater the risks.

Thiamin Deficiency

Chronic alcoholism is strongly associated with a lack of vitamin B1, also known as thiamin. This is due to active inhibition of the absorption of thiamin across the gut wall by the alcohol, sometimes accompanied by a poor intake of the vitamin in alcoholics. As thiamin is required for the nervous system to function normally, a lack of vitamin B1 can lead to a group of neurological symptoms known as Wernicke's encephalopathy. The most common symptoms are:

• Ataxia - a lack of muscle coordination by the brain leading to difficulty moving and walking.
• Ophthalmoplegia - paralysis of the muscles that control eye movement.
• Confusion - a lack of ordered thought and behaviour.

Other symptoms include nystagmus, a left-right scanning motion of the eyes usually seen during motion, ptosis, in which the eyelid droops due to lack of contraction of the muscle which holds it up, and generalised central nervous system signs such as reduction in consciousness and a change in pupil response to light. Wernicke's can also cause nondescript symptoms such as headaches, vomiting and weight loss.

More worryingly, if Wernicke's encephalopathy is not treated with thiamin either by mouth or by intravenous or intramuscular injection, the disease may progress to Korsakoff's syndrome, in which the individual starts to lose the ability to form memories and presents with amnesia on top of the aforementioned symptoms. By this stage, irreversible damage has occurred, although treatment with urgent thiamin will still restore some of the lost functionality and prevent further damage. However, both Wernicke's and Korsakoff's are precipitated and worsened by glucose injection in a thiamin-deficient patient, and so it is vital that the thiamin is given first. If left untreated, Korsakoff's syndrome will progress leading to psychosis, coma and then death.

The Nervous System

As well as thiamin deficiency, chronic alcohol abuse can lead to other vitamin deficiencies due to malabsorption, early cognitive decline known as alcohol-induced dementia due to shrinking of the cortex of the brain, and damage to the optic nerve leading to a decline in eyesight more popularly associated with methanol. In adolescents, excess consumption can lead to impaired memory and thus learning difficulties. Chronic drinking can make the individual prone to falls and fits, and can cause peripheral neuropathy and polyneuropathy, in which peripheral nerves (ie those running to the periphery of the body) start to malfunction.

The Heart

Over time, alcohol consumption can lead to atrial fibrillation, whereby the smaller chambers of the heart fail to contract properly and may harbour potentially-dangerous blood clots. Chronic drinkers are thus more prone to both heart disease and stroke, and are at a higher risk of sudden death due to heart failure, especially during a drinking session.

Anaemia

Excessive alcohol consumption can cause anaemia, which is a reduction in the number of red blood cells circulating the body leading to tiredness, shortness of breath, fainting and, in more serious cases, a dangerous drop in blood pressure. There are a number of causes of anaemia in the chronic alcoholic, and these include suppression of the bone marrow, which produce the red blood cells, a lack of iron or folate, both of which are required for red blood cell production, and gastrointestinal bleeding (see below).

The Gut

Alcohol is well-known for its effects on the gut, which range from irritation of the stomach and diarrhoea to obesity caused by the high calorie intake. However, continued stomach irritation can lead to chronic gastritis, which is can then progress to cancer of the stomach. Alcohol can also encourage peptic ulcers, erosions of the stomach wall, and varices, swollen vessels in the gut wall which are prone to bleeding. Meanwhile, repeated vomiting due to excess alcohol intake can lead to oesophagitis (inflammation of the gullet) and an increased risk of oesophageal cancer.

Pancreatitis

Alcohol abuse is a major cause of inflammation of the pancreas, an organ responsible both for secreting insulin into the bloodstream to control blood glucose levels, and for secreting enzymes into the small bowel to break down food. Pancreatitis can thus produce both diabetes mellitus and malabsorption of food from the gut, but more commonly presents as abdominal pain with nausea and vomiting. Acute pancreatitis can be life-threatening, with complications including multiple organ failure and acute respiratory distress, while chronic pancreatitis leads to nausea, weight loss, diarrhoea and steatorrhea (fatty stools).

Liver Disease

Half of all chronic alcoholics have some form of liver disease. At first, chronic alcohol consumption may only lead to a reversible accumulation of fat in the cells of the liver, known as steatosis. This produces the classic 'fatty liver' seen during the early stages of alcoholic liver disease, and which will normally revert to healthy liver once drinking is stopped. Meanwhile, there is also the risk of inflammation of the liver, known as alcoholic hepatitis, which is treatable through immune suppression with corticosteroids.

However, continuous damage to the liver produces scarring known as cirrhosis - this scarring prevents the liver from regenerating, and thus leads to irreversible damage. Cirrhosis will eventually produce a shrunken and failing liver which blocks the drainage of the blood from the gut, thus leading to swollen vessels which may bleed into the gut depending on their location. Liver failure leads to confusion and coma as toxins accumulate in the bloodstream, a lack of clotting due to a lack of the required clotting factors usually produced by the liver, and is thus a terminal disease unless a transplant is provided. Once cirrhosis has occurred, the survival rate over five years is around 45%, or 75% if drinking is stopped.

Other Problems

Alcohol abuse is also associated with an increased risk of cancer of the mouth, pharynx (voicebox) and breast, can cause acute myopathy (degeneration of muscles leading to weakness), and leads to foetal alcohol syndrome if alcohol abuse continues during pregnancy. Finally, alcohol abuse has been linked to social, economic and educational problems in later life, and alcohol withdrawal can lead to tremor, fitting, disturbing hallucinations and, most worryingly, death.

Worried?

If you're worried about the ill effects of drinking too much, start by asking yourself the following questions:

• Do you ever feel that you should cut down on your drinking?
• Do you ever become annoyed if people criticise you for drinking?
• Do you ever feel guilty about your drinking habits?
• Do you need an eye-opener in the mornings to clear a hangover or to steady your nerves?

This is known as the CAGE questionnaire¹, and three-quarters of those who answer 'yes' to two or more questions will have an alcohol problem. If you find you have a score of two or more, you should consider talking to your doctor about your concerns. The same goes if you exceed the recommended daily limit² almost every single day, or if you are admitted to hospital with an alcohol-related problem - these two factors form part of a longer test called the Paddington Alcohol Test.

And Finally

Thankfully, life isn't all doom and gloom: studies have shown that drinking within moderation can decrease the likelihood of heart disease, stroke, gallstones, kidney stones, vascular disease, osteoporosis and diabetes, and is associated with a modest increase in longevity. Red wine is particularly good for your health when consumed in small amounts, while beers and spirits are less effective.

Please Note: h2g2 is not a definitive medical resource. If you have any health concerns you must always seek advice from your local GP. You can also visit NHS Direct or BBC Health Conditions.