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The express route to mental illness

From Wednesday's Globe and Mail

From the lab to the legislature, the push is on to recognize and treat addiction as a mental illness. A growing body of research finds addiction is not the result of bad behaviour or weak character, but the result of biochemical disruptions in the brain that genetically vulnerable people are, on their own, powerless to overcome. It distorts mood, clear thinking and compulsion control. People who suffer from it, scientists believe, can no more talk themselves out of their dependence any more than people can talk themselves out of depression.

The American Medical Association first recognized addiction as a disease in 1956. Still, there remain doctors who refuse to treat patients with addictions, patients too ashamed to seek treatment and pharmaceutical companies reluctant to develop drugs for addicts. But Remi Quirion, professor of psychiatry at McGill University and scientific director of the Institute of Neurosciences for the Canadian Institutes of Health Research, said, “More and more experts agree addictions are a brain disease.

“Addictions are themselves a mental illness.”

As with any mental illness, addiction runs in families, impacted by genes, stress and lifestyle risk factors. The right combination can make a person dependent on a psychoactive substance from the first try.

Over the last decade, researchers have found that addiction upsets an ancient brain region known as the reward pathway, hijacking mood and memory and the pleasurable responses we normally derive from eating or having sex. Different drugs, such as marijuana, cocaine or alcohol, work differently on the brain, but all of them foul up the reward pathway's normal function. The addict seeks out the substance in the same way the hungry seek food. Going without makes addicts irritable and unable to concentrate. But research shows those afflicted feed their addiction not out of the desire to be high, but from the intense fear of the symptoms they suffer going without.


Scientists have identified gene types that lead to addiction. Genes that make people metabolize drugs quickly, for example, make them more likely to become addicted quickly. Some genes produce a euphoric response to alcohol similar to a heroin high. Other genes govern dopamine levels in the brain.

Overall, scientists estimate that genetic factors account for 40 to 60 per cent of a person's vulnerability to addiction. For example, research shows that 33 out of 100 will become addicted to cigarettes after the first few tries, 16 out of 100 to cocaine.


Research in the U.S. suggests that more than half of people with a mental illness also suffer from a substance dependence, compared with 6 per cent of the general population.


A recent national survey backed by the Canadian Institutes of Health Research, based on interviews with 14,000 men and women, has found strong links between depression and alcohol. The findings suggest it is not how often you drink but how much. People who binge drink are more likely to be depressed than people who frequently consume moderate amounts of alcohol. The pattern appears to be especially pronounced in women, said lead investigator Katherine Graham, a researcher with the Centre for Addiction and Mental Health.


Researchers have found that repeated cannabis use in adolescence can increase the risk of developing schizophrenia – particularly in young people predisposed to the disease.

A 2005 report in the British Medical Journal concluded that teenagers who used marijuana three times before age 15 faced a 10-per-cent chance of developing schizophrenia by age 26, compared to a 3-per-cent risk in the general population.


Research shows that addictions are more difficult to break if they are learned at a young age. “You don't forget how to ride a bicycle and you don't forget how to be an addict,” said Charles O'Brien, psychiatry professor at the University of Pennsylvania.

“It's a physical response in the brain….even when the drug is out of the body for a long time, there are changes in the brain that do not go back to normal – there's always the risk of relapse.”


The Diagnostic and Statistical Manual, the dictionary of mental conditions for clinicians in North America, lists addictions as Dependence Disorders. But a move is afoot to call addiction a mental illness in its own right in the next edition of the DSM, due in 2012.

Charles O'Brien, who chairs the committee reviewing the addiction category, says the name change could help combat stigma and help addicts get the treatment they need. “We don't blame someone with schizophrenia for the disease, but we do blame the addict… when addiction is a chronic disease that becomes involuntary.”

In March, the U.S. House of Representatives passed a bill requiring group health insurance plans to provide the same coverage for substance-use disorders and mental illness as for medical and surgical services. In Canada, treatments for addiction remain a patchwork of public, private and not-for-profit programs.

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Return to Breakdown: Canada’s Mental Health Crisis

Face it. Fund it. Fix it.

In Breakdown, The Globe and Mail documents the enormous, unaddressed cost of mental illness to Canadian individuals, families and society. The series closes with a search for solutions.


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