What’s the appeal?
When we talk about alcohol as a recreational drug we really mean ethanol, a particular type of alcohol that is produced when sugar is fermented by yeast. Alcoholic drinks are usually made from fermented fruits or grains, and usually fall in to three categories: beers, wines, and spirits. Alcoholic drinks have a long history of use in the UK, and are very much ingrained in UK culture. Ale was extremely popular in the Middle Ages, though it was much weaker, and consumed daily in large quantities.

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And while underage drinking is discouraged these days, alcohol is still very much part of British culture. Office of National Statistics figures from 2014 found that only 16% of white adults in Great Britain reported being teetotal (although the figure was substantially higher for other ethnicities, see table 4 here).

Short term effects
Most people reading this are probably familiar with the symptoms of alcohol intoxication. Alcohol takes between 10 minutes to an hour to get in to the bloodstream, and its effects vary depending on the dose. After an average drink, you might feel more sociable and warm, the feeling described as “tipsy”. At this level of alcohol consumption your heart rate has increased, and your blood vessels dilate. Your inhibitions might be slightly lowered too, and you might feel relaxed.

As you drink more alcohol, the effects get more pronounced. You can start to feel lightheaded, and you might struggle with fine motor tasks (ever tried threading a needle while drunk?). As well as these physical effects, your judgement and decision making can become impaired too. This is why drinking in moderation can be so difficult – it’s easy when sober to decide that one or two drinks is all you’re going to have, but once you’ve had those drinks you might feel differently.

And if you carry on drinking from this point, things can get much worse. You might experience blackouts, you could end up nauseous and vomiting, your motor control might get worse, leading to stumbles and falls, and this, combined with impaired judgment, can lead to serious accidents.

There’s some evidence that alcohol intoxication might increase aggression, but at the moment it’s pretty weak. What might explain the fights that seem to occur more often among intoxicated people could be an increase in misinterpreting ambiouguously emotional faces. If you see a person not smiling when you’re sober, you might think nothing of it, but while drunk, you might misinterpret that lack of a smile as aggression. And if that person is drunk too, that misinterpretation could escalate.

Intoxication is also associated with increased risk of sexually transmitted diseases – when we’re drunk, we are more likely to partake in risky behaviours, and this can include unprotected sex.

Say Why To Drugs – the highs and lows of cannabis

Within the brain, alcohol affects almost every neurotransmitter in the brain. It’s a global or “dirty” drug, and this is why it can appear like a stimulant and a depressant depending on the dose and time after drinking.

Long term effects

Long term alcohol use is known to increase the risk of liver problems. Heavy drinking, even in the short term, can lead to a buildup of fat in the liver, which is a reversible warning sign of alcohol-related liver disease. If the liver isn’t given a break from alcohol to recover, more serious disease can set in, with symptoms often not being seen until the liver is very damaged (more information is available on the NHS website).

Alcohol is also causally associated with seven different cancers, including breast cancer, liver cancer, mouth cancer and bowel cancer. CRUK estimate that alcohol is responsible for 4% of cancer cases in the UK.

Alcohol can be addictive, and about 9% of men and 4% of women in the UK show symptoms of alcohol dependence. Alcohol tolerance builds up over time, meaning a person needs to consume more alcohol to get the same effect, and it can be a struggle to cut down even when a person has health problems.

There are also withdrawal symptoms when trying to quit alcohol, and these can include seizures and can potentially be extremely dangerous. Also, as alcohol tolerance will reduce if a person abstains, overdosing on alcohol during relapse is easily done and can have severe consequences.

Long term alcohol use can negatively impact on mental health. It has been linked to increased risk of depression and anxiety, to memory impairment, and to increased levels of stress. Although, as with other substances, understanding the links with mental health are more challenging than for physical health.

Say Why To Drugs: the smoke and mirrors of tobacco cigarettes

Can alcohol be good for you?
You’ve probably at some point seen headlines saying a glass of red wine is good for you. Sadly, the evidence doesn’t really back this up. There have been a few studies of a chemical called resveratrol, which is found in red grape skins (and therefore in red wine). In animal studies and cell culture studies, this chemical has been linked to benefits for diabetes, neurodegenerative diseases and even cancer. However, scaling this up to humans has been challenging, because the quantity of resveratrol you’d have to consume is enormous, and getting that dose, even in trials of resveratrol, has been very difficult. This doesn’t mean that resveratrol doesn’t have any beneficial effects, but at the moment we just don’t have enough evidence. And, of course, there are other chemicals in red wine, and we know that alcohol causes seven types of cancer. So to say that red wine might be beneficial for cancer is just plain wrong at the moment I’m afraid.

More controversial are the findings that suggest a beneficial effect of drinking a small amount of alcohol, compared to none, in particular around risk for heart disease or stroke. There is some disagreement in academic circles around this so called J-shaped curve, which I’ve written about before. This is again a problem with using observational cohort studies – people who don’t drink at all are different from people who drink a small amount, and accounting for these differences is difficult.

The science of hangovers

What do we still not know
There’s still a surprising large list of things we know little about regarding our drug of choice. We currently have a very limited understanding of hangovers – why do some people get them, while others can drink far more and feel fine the next day? We also don’t know with certainty about drinking a small amount during pregnancy and the risk that confers to the unborn child. At the moment, the guidelines in the UK recommend avoiding alcohol during pregnancy, but while we know heavy drinking while pregnant can lead to foetal alcohol syndrome, the effects of a small amount of alcohol are much less clear.