News

Why ‘users’ can’t say no

[ The University of Melbourne Voice Vol. 1, No. 13  3 - 17 September 2007 ]

By Rebecca Scott

Research at the University of Melbourne has shed new light on why long term drug users find it hard to say no, despite dire consequences to their health.

A study into the frontal cortex, the key region of the brain involved in decision making, has shown that drug users have to place much greater demand on the brain to control impulses.

The two year study, by researchers Dr Murat Yücel and Dr Dan Lubman of the ORYGEN Research Centre and the Melbourne Neuropsychiatry Centre, was published recently in the prestigious international journal Molecular Psychiatry.

“Drugs can capture and hijack some parts of the brain,” says Dr Yücel. “In this study we found the frontal cortex, an area that is essential for exercising control over thoughts and behaviours, was working inefficiently.

“These findings may help explain why it takes addicted individuals enormous effort to exercise control over their drug-taking behaviour in the face of adverse consequences, and why they are vulnerable to relapse back into uncontrolled, compulsive patterns of use.”

The studies involved brain-imaging technology to probe the physiological and biochemical properties of the frontal cortex. Participants were asked to complete a test of self-control in which they had to overcome an automatic response in favour of a more controlled alternative response, thus requiring them to control their impulsive tendencies.

The researchers discovered two important differences between the opiate-using group and a group who have never used heroin.

Firstly, the opiate-using group needed to activate more of their brain by placing greater physiological demand on it to avoid making an error on a test of self control.

Secondly, brain cells in the frontal region were revealed to be less healthy than the non opiate-using group.

The researchers say long term drug users have a reduced level of biological resources and find it hard to stop.

Dr Lubman, an addiction psychiatrist, says this new evidence is likely to lead to the development of innovative strategies for the treatment of addiction.

“These findings tell us we need to provide a combination of pharmaceutical and psychological treatments that will help bolster the efficiency of the frontal cortex and hence the individual’s ability to stop their urge to use drugs,” he says.

“To improve treatments for long term drug users we need to understand at what stage these brain deficits occur. The next question we need to ask is are these latest research findings a consequence of addiction or do they explain people’s vulnerability to problematic drug use?”

Dr Yücel and Dr Lubman would like to examine whether these processes recover with abstinence.