Research Profile - Is it really a slippery slope?

Brandon Marshall

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Back in 1938, the movie "Reefer Madness" told a dark tale of the descent into murder, rape and suicide after trying the supposedly harmless marijuana. No one claims crystal meth is harmless – according to Toronto's Centre for Addiction and Mental Health, using crystal meth at high doses can cause violent behaviour, anxiety, confusion, insomnia and weight loss, as well as increased heart rate and blood pressure, potentially leading to stroke and death. But while all sorts of dire consequences have been attached to the use of crystal meth, there has been little evidence produced to date.

Brandon Marshall would rather that people responded to the problem of crystal meth use among youth with facts, not fiction. This doctoral student at the University of British Columbia is committed to supplying those facts. He has surveyed the literature and conducted empirical research to find out who uses crystal meth, why occasional users turn into daily, or heavy, users and whether this use has unforeseen consequences.

Among his findings? Well, first, using crystal meth is not a pre-ordained first step on the road to perdition. But there are some factors that spur on the transition from an occasional user to a heavy user. For instance, youth who are more street-involved are more likely to make crystal meth their drug of choice, as are people in the sex trade. Part of the reason, Marshall says, is that crystal meth keeps you more awake and alert, making it easier to guard your possessions on the street or gain more customers if you're a sex worker.

And while Marshall didn't investigate whether using crystal meth leads to using other drugs, he did find that many users who begin by snorting or smoking the drug move on to injecting it. It is this group Marshall is most concerned with, as injection drug use is more likely to lead to public health problems such as HIV infection or sexually transmitted infections.

Marshall also found that the health impacts of crystal meth use are not as significant as has been thought. In fact, going by records at St. Paul's Hospital in Vancouver's Downtown Eastside, only daily users had an elevated use of the emergency department, while those who use it more rarely don't experience the same health risks.

Marshall's work also found that crystal meth is linked to poor mental health outcomes, including depression, psychosis and suicide. In light of recent research from Vancouver and Thailand that found that some people use crystal meth to self-medicate for depression or schizophrenia, however, Marshall is not willing to say if there's a causal link.

"It's a real chicken-and-egg argument," he says. "It's my sense that it's probably working both ways."

Marshall's research has also convinced him that existing public health interventions are not sufficient to reach young crystal meth users, particularly as many feel uncomfortable using services that target other injection drugs users.

"This research really suggests that we need a mix of interventions to address crystal meth use," he says. "We need 'low-threshold' services geared to youth."

Low-threshold services, Marshall says, are those that are easy to access, for instance by going to youth where they are, rather than expecting youth to come to them.

Marshall, whose research was supported by the prestigious Banting and Best Doctoral Research Award, has completed his doctorate and is now moving on to Columbia University in New York City for a post-doctoral fellowship. While there, he will continue his work, this time focusing on mathematical modeling to better predict the initiation of all injection drug use, not only crystal meth. He will also continue to collaborate with his colleagues in British Columbia and he is looking forward to coming back to Canada to continue his research.

The Study

Brandon Marshall's research attempted to better understand the link between crystal meth use and sexual and injection-related risk behaviour among street youth and injection drug users. His study had two areas of focus: the initiation of crystal meth use and typical patterns of use; and the health risks associated with crystal meth use. To carry out his research, he first surveyed the relevant literature. He then used data from two large research studies, one of 1,500 injection drug users and one of 600 street-involved and homeless youth. From these two cohorts, a subset of about 500 reported crystal meth use, and Marshall looked at the trajectories of use among this cohort. His goal was to identify factors that predict frequent use of crystal meth and engagement in sexual and injection-related risk behaviour.

"The link between crystal meth use and mental health is a real chicken-and-egg argument. It's my sense that it's probably working both ways."
-- Dr. Brandon Marshall