Research Profile – 1 + 1 = 3
Dr. Sean Barrett
Drug users often take two substances at time, sometimes creating a third psycho-active agent that can increase the risk of an overdose
When it comes to drugs, the whole is definitely greater – and more dangerous – than the sum of the parts, according to Dalhousie University's Dr. Sean Barrett.
Take, for example, someone who drinks alcohol and then consumes cocaine.
"Their body creates an entirely new substance from the two drugs called cocaethylene," says Dr. Barrett. "And when you create these new byproducts, they can be more dangerous than either of the drugs alone."
At a Glance
Who - Dr. Sean Barrett, Dalhousie University, Department of Psychology.
Issue - Traditional models for diagnosing and treating substance use disorders tend to focus on problems associated with individual substances. However, many drug users take multiple substances at a time.
Approach - Dr. Barrett has developed an interview technique to assess patterns of simultaneous polysubstance use.
Impact - The work he is doing will benefit research into drug addiction by examining the effects of multi-drug use. It is already helping front-line addiction workers identify and treat people with polysubstance use problems.
He calls taking more than one drug "simultaneous polysubstance use" and has evidence to suggest it's anything but rare. His 2005 study of young people who attend raves showed that while less than 3% took no drugs and 17% used just one, 80% reported polysubstance use.
"In many cases, drug users are doing 'mini-experiments' to maximize the positive effects of some drugs and minimize the negative effects. They are acting as pseudo pharmacists in the different combinations of drugs that they use."
Because of this – and because mixing drugs can increase the risk for an overdose – he believes health researchers need to study substance use in a more comprehensive way: by focusing on how people combine different drugs and examining the effects it has on them.
"A lot of what we understand about drugs stems from doing research on single substances," says Dr. Barrett. "We know a lot about the effects of ecstasy on the brain or cocaine on the brain, but we don't really have a good knowledge base for the effects of mixing substances the way they are used in the drug-taking community."
To help build that knowledge base, Dr. Barrett has developed a structured interview technique to identify polysubstance use. He conducts his research in cooperation with addiction treatment centres in Halifax.
"If you want to understand how drug users take drugs, you have to get the information from the drug users themselves," says Dr. Barrett. "Our goal is to figure out exactly what people are doing and to develop laboratory models that accurately reflect the problems as they exist."
Working directly with drug clinics helps him in his research and provides front-line clinicians with up-to-the-minute research findings.
"Right now we're working with a methadone program for people addicted to opioids. There are also very high rates of other substance use in the population. As we discover how individuals are using the drugs, we are able to say to the practitioners 'this is how your clients are co-administering substances.' So, in some cases, the knowledge translation is immediate."
Cindy MacIsaac, Program Director at Halifax's Direction 180 clinic, says the work Dr. Barrett is doing is "absolutely" helpful.
"As a non-profit organization, we don't have the resources or capacity to examine issues beyond the day-to-day crisis mode we operate under," she says. "Academia and community together can help to shift thinking and influence funding or policy. More importantly, it helps us to identify opportunities to improve our approach to respond to the people we are working with."
The Study
Funded by the Canadian Institutes of Health Research, Dr. Barrett's research team is conducting interviews with drug users at addiction treatment centres.
While people tend to have difficulty recalling their drug use in general terms, Dr. Barrett has found they can be remarkably precise when asked to describe particular drug-taking experiences such as their first time, most recent time or an incident when something significant – such as an overdose – occurred.
"If we direct their attention to a specific memory – when and where was it? who were they with? – they are able to provide details more reliably. We get them to walk us through the entire substance-taking occasion, beginning with the first substance that they used, how much they used, what they did next."
Dr. Barrett's team then verifies the information by looking for biomarkers – for example, seeing if the drug use shows up in urine screens.
"The two exceptions are cannabis and alcohol, where you can have relatively pure users of these drugs. But if you move into any other drugs – cocaine or hallucinogens or any other class of drugs that's misused – multiple substance use is the rule rather than the exception."
-- Dr. Sean Barrett