Canadian researchers have genetically-engineered a mouse that had unexpected resistance to the lure of cocaine, offering new insight on addiction at a molecular level in the brain.

The study was published today in the peer-reviewed journal Nature Neuroscience, led by scientists at the University of B.C. and University of Calgary.

Based on previous studies involving gene mutation, the team focused on a type of protein that helps binds cells together, known as cadherins, which are believed to be important for learning and addiction.

Bamji's team genetically engineered mice that had higher levels of cadherin and conducted an experiment using the drug cocaine.

A group of mice was injected with cocaine in a specific chamber of a cage, the goal being: the mice would associate the drug with being in that area. Their behaviour was observed over a number of days.

What the team found: the normal mice almost always gravitated to the chamber where they were injected with cocaine, while the mice with the extra cadherin spent only half as much time there.

Cadherin Synapse

A diagram that shows the difference between a mouse with the extra protein cadherin and a regular mouse. (UBC)

Bamji said her team believes the extra cahderin prevented the transmission between neurons and the pleasurable memory of the drug didn't stick.

"What happens when we have too much cadherin — or glue — is that it really holds on to the old type of receptor and prevents the new one from from getting to that right spot."

"So basically what happens is: no synapse strengthening, no learning no addiction," said Bamji. 

The findings show that people with genetic mutations associated with cadherin may be more prone to substance use problems.

No 'magic' pill to curing addiction

Bamji said while the study doesn't show how researchers can help people afflicted by addiction right now, it does reaffirm the thinking that addiction is more complicated than just a series of bad choices.

"It wasn't that long ago where we just kind of thought of people who had addiction disorders as just being weak and that's certainly not the case," said Bamji.

"There's accumulating evidence — and ours is just one of them — suggesting that addiction is really a biochemical disorder."

Bamji said while there's no "magic pill" to make people less addicted or less vulnerable, the hope is that research like her team's can lead to greater confidence in predicting who is more vulnerable to drug abuse.

"In this day of genetics when we [can better] understand genes and which mutations what might cause this predisposition to addiction, we might have a better idea about the underlying cause of somebody's addiction," said Bamji.

As the province grapples with the opioid crisis, Bamji said it's essential to understand addiction in a scientific way.

"It's very important that these studies come out to continually remind the public that addiction is a matter of biochemistry," said Bamji

"If we look at it that particular way ... the way we design our policies and the way we deal with these people is going to be very different."