What gets us hooked?

Some people are consumed by drugs or alcohol, while others indulge and walk away. Now doctors are beginning to understand why. By Kate Hilpern

(AFP/Ed Jones)

My destructive side has grown a mile wide, she sang on her first album in 2003. The cause of Amy Winehouse's death has not yet been confirmed, but her struggles with drug addiction, and more recently alcoholism, would suggest a link is likely.

But why is it that one person can drink like a fish and never become an alcoholic, and yet others seem to slide so easily into dependency? And can we really become addicted to chocolate.

Addiction starts with exposure, says Dr Gillian Tober, president of the Society for the Study of Addiction. "It's generally for social reasons – friends or a boyfriend or girlfriend – and it's often not pleasant. The reward is merely social. It then becomes reinforced and casual use shifts to dependence."

Drugs directly feed the reward circuitry of the brain, she says, and the brain learns to look forward to the thrill. Tolerance occurs as you demand more each time. Physiological dependence – addiction – then emerges. "It is this area – the mechanisms involved in the addictive process – where research has been most progressive and this has meant that we have more effective medications to help people come off nicotine, alcohol and opiates," says Ilana Crome, professor of addiction psychiatry at Keele University, in Staffordshire. "But we still don't know what actually causes addiction."

Indeed, many people drink but few are addicted. Likewise, when opiates have been given to cancer sufferers for many years, studies show that only a few become addicted.

"There is no single reason why this is the case," says Dr Tober. "There are not even any particular personality characteristics that predispose people to becoming addicted. Every sort of personality can become addicted."

Indeed, a long-term study of 500 men, which began in the 1940s, exploring why some people become addicts and others do not, found there were no consistent personality types, says Bob Adams, consultant psychiatrist in York NHS Trust. "They concluded that it's possible for anyone, under the right circumstances, to become addicted." But the Faculty of Addictions at the Royal College of Psychiatrists claims there are three key risk factors – biological, psychological and social. Biologically, addicts may be wired differently, particularly in the brain's orbito-frontal cortex, the part of the brain involved in weighing up the pros and cons of a particular action, they say. Scientists at the Neurocentre Magendie in Bordeaux, France, have found that those who became addicts had brains that were incapable of returning to normal after regular drug abuse. Long-term drug binges change the way people's minds work.

"Scandinavian studies have shown that the children of alcoholics are more likely to become alcoholics themselves, suggesting there is a genetic component," adds Dr William Shanahan, lead addiction consultant at Capio Nightingale Hospital in London. But, he says, some would not see the addiction through. "You still have free will, after all, so you might recognise it in others and get frightened off, or something else, such as religion, acts as your salvation. It's often the case that if you find a non-drinker, you can usually find a drinker somewhere in their lives."

The second risk factor is psychological trauma. Childhood neglect, abuse or bereavement is common among addicts, says Harry Shapiro from DrugScope. For others, the trauma comes later – a bereavement, loss of job or late-onset anxiety might make them turn to the bottle or drugs. Research from the 1990s found there may be a biological link here, too. Levels of feel-good chemicals in the brain, mainly serotonin and dopamine, can be reduced by a traumatic event such as divorce. People who become addicted to certain substances are subconsciously trying to boost the levels of these feel-good chemicals, studies found.

Thirdly, there are social risks, including the availability of a drug, exposure to others who take it, and social deprivation. "Most of the people who come forward for heroin or crack use are pretty impoverished," says Mr Shapiro.

But because some addicts don't fall into these categories, it is impossible to predict who may become an addict, says Dr Shanahan. But Dr Farrukh Alam, consultant psychiatrist and clinical director at Central and North West London NHS Foundation Trust, believes we may be able to identify when someone has a propensity towards addiction. You can spot some traits as early as late adolescence, he says. "We know, for instance, that among those most prone are people with compulsive or impulsive types of behaviour, an unwillingness to take responsibility for their own actions or who are stressed and anxious even in times of relative ease.

"The age of initiation is relevant, too," he says. "The earlier you start to misuse substances, the more likely you are to develop chronic dependence in later life. Although all this is an imprecise science, you can also tell which kind of drugs people are more likely to become addicted to. Men, for example, appear to have more problems with drug use, while women are more likely to show dependence to prescribed medication, such as painkillers."

Certain occupations have also been shown to be higher risk – media, entertainment, catering and the military among them.

Some people believe there's an "addictive personality"– that obsessive side to their personality that gets them practicing at something until they're the best. It would certainly explain why so many people famous for their talents – Andre Agassi, Paul Gascoigne, and Amy Winehouse among them – wind up in rehab.

"The problem is there's no clinical evidence for an addictive personality," says Mr Shapiro. "It seems to me these terms are mainly used to help attract people to treatment. Embedded in the 12-step programme, for example, is the idea that addiction is a disease. Now, of course, addiction not going to tick all the same boxes of medical diseases, but it does have therapeutic value in that it can stop people blaming themselves and consequently seek help."

The term addiction often brings to mind drugs and alcohol. But can you become addicted to anything? Certainly gambling is accepted as a behaviour the brain can become hooked on. Sex addiction is also becoming a hot topic. The NHS is reconsidering it as a genuine disorder after the American Psychiatric Association added it to its main diagnostic manual. The theory goes that like cocaine and other drugs, sex and gambling increase levels of dopamine, which means you can get hooked on the high.

Even running can be an addiction, according to some scientists. The medical journal Behavourial Neuroscience reports that "excessive running shares similarities with drug-taking behaviour". It reports that too much of it sparks a reaction in the brain that is similar to the effects of heroin – and is just as addictive. Sudden withdrawal can lead to trembling, writhing and teeth-chattering.

But not everyone is convinced. "I think addiction has become a lazy word for a bit of an obsessive habit, which is not the same," says Mr Shapiro. "How many people do you know whose job has gone out of the window or who have neglected everyone in their lives because they wanted to buy more shoes, get a better tan or eat more chocolate?"

the signs of addiction

How to tell if you're an addict. If you answer yes to three or more of these questions, it is probably time to seek help.

Do you crave the substance or behaviour?

Do you have difficulty controlling your intake?

Have you started to become tolerant to it – ie, you need increased amounts just to produce the same effects?

Do you get physiological withdrawal symptoms, such as sweating, anxiety and tremors?

Do you neglect other interests to feed your habit?

Do you persist in its use despite understanding the harmful consequences?