Scientists find a new target in the treatment of addiction

Scientists who study addiction know its prevalence is getting worse and extending beyond alcohol and drugs.

In our society, the whole concept of compulsive behaviour is explained—sometimes, too easily—as an addiction. Buy too many things you don’t need? Call it a shopping addiction. Play video games all the time? That’s an addiction too.

Dr. Shimi Kang, an addictions specialists in the department of psychiatry at the University of B.C., says one of the reasons for the growing spread of addiction is the things we’re addicted to are part of our culture and even promoted, like caffeine, sugar, alcohol, smoking.

“For many years, treating addiction wasn’t part of the medical system. There were AA programs but we lacked the competency to understand addiction and its prevalence. For anyone who has experienced it, or know someone who has, they know how truly devastating addiction can be," she said.

Scientists have made tremendous new discoveries over the last two decades in understanding how or why addition is triggered and the latest one, originating from McGill University, supports the existing science on the genetic underpinnings of addiction, according to Kang.

The study, published in Molecular Psychiatry was led by scientists at McGill University and Douglas Mental Health University Institute in Montreal and at the CNRS INSERM UPMC in Paris, provides some insights into the genetic mechanism that an drive addict's need to get high.

Brain cells communicate with other brain cells via chemicals known as neurotransmitters and the classical neurotransmitters are dopamine, serotonin, acetylcholine and glutamate. They all trigger different reactions. Fluctuations of serotonin can impact your sleep cycle, pain control and your immune system. Dopamine can both trigger depression or drive our motivation to get thing done.

More than a decade ago, Dr. Salah El Mestikawy and his team first discovered that some neurons use two transmitters, meaning they can respond with both “yes” and “no” signals.

In the latest research published in Molecular Psychiatry, the scientists showed they can now shut down the cell’s “no” response in mice who showed a marked predilection for cocaine.

“We silenced one of the two languages of the neurons, we took away the no system and explored their behaviour in genetically-modified mice and we found out that these mice were ingesting cocaine like crazy,” said El Mestikawy. “Then we wondered whether this was relevant to human beings.”

Their study explains the mechanisms underlying reward behaviour, while identifying an unsuspected target in the treatment of addiction.

The researchers, using a small study group, found humans with the mutation of a key gene were 10 times more vulnerable to very severe forms of addiction. “What we have found is a genetic marker to addiction,” said El Mestikawy.

10 times more common in addicts

The research showed that the gene mutation shows up in 0.5 per cent of the population. But among addicts, it occurs in 5 per cent.

“Even though it’s a huge increase of ten times more among addicts than among people with no psychiatric behaviour, it’s still just 5 per cent of addicts. That means it’s 95 per cent something else, genetic problems, educational problems, many other things. This is only one genetic marker and we can’t predict how many other markers there are,” said El Mastikawy.

El Mestikawy said psychiatric disorders are very complex pathology, not like catching the flu or breaking an arm. “There is not one gene responsible for psychiatric disorders. It’s a combination of genes and this explains why the symptoms of people with psychiatric disorders are so different.”

Kang, the addictions specialist, echoed that sentiment. The study led by El Mestikawy should lead to further research on the neurochemistry underlying that may possibly form future medication therapies.

Dr. Steven Melemis, an addiction medical doctor in Toronto, said the research published in Molecular Psychiatry explains one possible mechanism for addiction.

“Addiction is definitely a multifactorial disease. Other neurochemical mechanisms for addiction have been discovered. Most importantly, understanding the cause of addiction is not necessarily helpful in treating addiction,” he said.

Melemis said the treatment for addiction still is based on developing healthy coping skills. Scientist El Mestikawy said it’s always an interaction between genes and a person’s environment and life history.

The people with that mutated genetic marker are highly motivated by a reward system. For some, this can be channeled into getting higher grades in school, for others it will be directed into addictive behaviour.

“We need to educate kids from a very young age and we need to tell those who need drug or computer games or alcohol we need to tell them early that addiction can happen to them,” he said. “When you have an addiction, something is malfunctioning in your brain.”