Sex, Drugs and Chocolate: The Science of Pleasure. Paul Martin

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СКАЧАТЬ of consciousness might in part be a consequence of our playfulness.

Harm

      Recreational drugs provide pleasure and relief from displeasure. They also cause vast amounts of harm and suffering to individual users and society as a whole. In the UK alone, the estimated economic costs of recreational drug use are as much as £16 billion a year in terms of health care, social costs and crime.

      Addictive drugs such as heroin, nicotine and alcohol debilitate and kill people in large numbers, whether from chronic illness, overdoses or accidents. In the year 2005, for example, there were just over 1,000 deaths in England and Wales involving heroin, morphine or cocaine. Alcohol and tobacco kill far more. In the UK, where the alcohol-related death rate has more than doubled since the early 1990s, well over 8,000 deaths a year are directly related to alcohol consumption.¹³ This figure does not include the many deaths caused by alcohol-fuelled accidents, violence or vehicle crashes, neither does it include deaths from the numerous diseases for which alcohol is known to heighten the risk, such as many forms of cancer. According to some estimates, the total number of deaths to which alcohol contributes in some way may be as high as 40,000 a year in England and Wales alone. The corresponding figure for tobacco is almost three times higher, at around 114,000 deaths a year.

      Legal recreational drugs – specifically, tobacco and alcohol – cause immense damage to national health, far outstripping the effects of their less widely-used illegal counterparts. An estimated 1.5 million people in the UK are addicted to alcohol. According to government estimates, up to 17 million working days are lost each year in the UK as a result of alcohol, and its misuse costs the economy around £6.4 billion a year in lost productivity. The picture is not dissimilar in the USA, where approximately a fifth of adults abuse alcohol at some point in their life. Worldwide, alcohol is estimated to be responsible for about 4 per cent of the global disease burden.

      Most victims of alcohol abuse die from liver disease, heart disease, accidents or acute alcohol poisoning. Most of those with alcohol-induced liver disease are social drinkers, not alcoholics. They may not even think of themselves as having a drink problem. In England, the number of cases of alcohol-related cirrhosis of the liver almost tripled over the period between 1996–7 and 2005–6. Doctors are now encountering patients in their twenties with end-stage cirrhosis of the liver, a condition that usually develops only after years of hard drinking. Alcohol heightens the risk of many forms of cancer, including cancers of the mouth, liver and oesophagus. It may also increase the risk of breast cancer in women with a family history of the disease. Research has found that the sisters and daughters of women with breast cancer are themselves at greater risk of developing breast cancer if they drink alcohol daily.

      In the UK, as elsewhere, thousands of people die every year in road traffic accidents where alcohol has been a contributory or causal factor. Thousands more die or are seriously injured in alcohol-fuelled violence and domestic accidents. Alcohol is involved in more than half of all visits to hospital accident and emergency departments and orthopaedic admissions, and is a factor in about a third of all arrests made in urban police stations. In larger doses, it is capable of killing directly. On average, one person dies each day in England from acute alcohol poisoning. The typical victim is a young person who has been celebrating with friends. Alcohol kills by suppressing the brain circuits that control breathing and the cough reflex; the victims of alcohol poisoning often die from lack of oxygen or because they inhale vomit into their lungs, causing respiratory failure.

      Sexual crime is another, often underestimated, risk from alcohol. Every year, women and men are raped while incapacitated by alcohol. They often believe their drink must have been spiked with a date-rape drug such as Rohypnol, although the evidence suggests that this may be less common than often assumed. A 2006 study by the UK Association of Chief Police Officers found that only one in ten cases of alleged sexual assault was suspected of being drug-assisted. None of these cases involved Rohypnol and only a few involved another date-rape drug (GHB), whereas almost all of the date-rape victims said they had been drinking, some of them heavily. The most common method of spiking drinks is with more alcohol. It is likely that some of the rape victims who thought they had been drugged had in fact been very drunk.

      As to tobacco – well, I won’t bore you by rehearsing all the baleful statistics about the toll of death and disease for which it is responsible, though I will mention an authoritative analysis which calculated that a regular smoker will reduce their life expectancy by an average of ten years. This startling statistic reinforces the point that smoking is the most dangerous thing that most people will ever do in their lives. It remains the biggest single cause of preventable death on the planet. Between them, alcohol and tobacco – those legal recreational drugs we can buy in the high street – account for approximately 90 per cent of all drug-related deaths in the UK. They are also among the leading contributors to disease and premature death worldwide.

      Cannabis, the most popular of the illegal recreational drugs, used to enjoy a reputation for being relatively safe. But that reputation has been eroded in recent years, as a growing body of evidence has linked it with a range of medical risks. The most serious concerns have arisen from research indicating that cannabis can increase the severity of existing psychotic disorders and induce psychotic symptoms or even full-blown psychosis.¹⁴ Some individuals appear to be much more vulnerable to these effects than others. Scientists remain uncertain as to why some people are particularly susceptible in this way, although the explanation is likely to involve some form of interaction between genetic and environmental factors.

      Overall, the emerging evidence suggests that cannabis may be a contributory factor in about 10 per cent of psychosis cases. One analysis published in 2007 concluded that frequent use could double the risk of developing schizophrenia and other psychotic illnesses. That said, psychotic illnesses remain relatively uncommon, in comparison with many other diseases, and most people who use cannabis do not develop them. Cannabis may also heighten the risk of depression and anxiety disorders in vulnerable individuals. One study found that non-depressed people who used cannabis were four times more likely than non-users to become depressed in later years. The use of cannabis preceded the onset of depression, implying that the correlation was not simply the result of already-depressed people turning to cannabis for relief. Even allowing for this and other evidence, there is little doubt that cannabis is still substantially less harmful than, say, cocaine or alcohol. Nonetheless, it is harmful, and probably more so than many of its users once believed.

      All recreational drugs are harmful and some are clearly much more harmful than others. So how should we go about judging the many different drugs in terms of the harm they cause? It all depends, of course, on how you define harm. Should harm be assessed only according to what the drug does to the individual who uses it, or should we also take account of its wider effects on the user’s family, community and society at large? What about drug-related crime, which has as much to do with legislation and social policy as it does with the pharmacological effects of drugs? Collecting high-quality data is another problem. Folklore, prejudice and untested assumptions are readily available when it comes to debating drugs, whereas verifiable scientific evidence is often in short supply. To make matters worse, scientific and medical journals have a slight bias towards publishing studies that find positive evidence of harm rather than those that have drawn a blank. The shortage of solid evidence means that much of the expensive effort to combat drug misuse, whether through law enforcement, treatment or education, may not always be targeted optimally at the drugs that cause the most harm.

      Fortunately, progress is being made on this front and we do now have ways of making more rational judgements about the relative harmfulness of drugs. A significant advance came in 2006, when the UK Parliament’s House of Commons Select Committee on Science and Technology published an authoritative analysis of how different recreational drugs compare in terms of the harm they cause. The report presented a systematic, СКАЧАТЬ