October 8, 2014

The way of the future

By Dylan Barmmer

Over the past few decades, great advances have been made in the study of the human brain, an incredibly complex and multi-dimensional organ. Addiction professionals and scientists are coming closer to understanding the biological basis for addition, as well as other mental health issues.

Studies have demonstrated that chronic drug users have fewer receptors than non-users in the reward pathways of their brain for the powerful neurotransmitter dopamine.

Some scientists believe this dopamine receptor deficit may reinforce addiction by causing users to seek out, through drug use, the “highs” they are unable to experience and receive naturally from surges in dopamine levels, like other people.

Crucial evidence for this view on addiction is provided by images of people’s brains taken during and following exposure to alcohol and drugs. These studies help explain the causes and inner workings of a predisposition to drug abuse, and yield insights into addiction.

This method of research is known as brain imaging.

A biological basis for addiction

In a 1989 study at Concordia University in Montreal, Canada, researchers R.A. Wise and P.P. Rompre tagged cocaine with a radioactive element, injected it into healthy volunteers, and used PET scans to measure the location and time-course of the substance.

The researchers soon discovered that cocaine went straight to the striatum, or the reward system of the brain. This research set the stage later brain-scan studies.

In a 2010 experiment, PET scans again were utilized, this time by a team of researchers at Vanderbilt University. The researchers were interested in finding out if people who are impulsive might have less active dopamine receptors than others.

The researchers monitored the brains of 32 healthy test subjects ages 18 to 35, who had no history of substance abuse. Before their second round of tests, the subjects were given a dose of amphetamine, which can stimulate the brain’s reward pathways, thus mobilizing dopamine.

“The people who had the highest levels of dopamine release reported subjectively stronger cravings after we gave them the drug,” the researchers wrote. These findings “suggest a neurobiological link between human impulsiveness and drug abuse vulnerability.”

To learn how brain imaging is being used now, and where it is going in the future, read the rest of this story in the latest issue of Renew.

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