A Wayne State University School of Medicine researcher believes he may be on the path to determining why some drug addicts who undergo rehabilitation are more prone to relapse than others, a finding that could lead to tailored treatment and improved success rates for those trying to kick addictions.

Mark Greenwald, Ph.D., director of the Substance Abuse Research Division and chief of the Human Pharmacology Laboratory in the Department of Psychiatry and Behavioral Neurosciences, is conducting research in an attempt to find true biological indicators of a predilection for addiction relapse.

Dr. Greenwald points out that substance abuse places enormous burdens not only on addicts but also their families, society, the healthcare and judicial systems, and, ultimately, taxpayers. While safe and effective treatments have emerged for certain substance use disorders, treatment for addictions is generally not indefinite. Also, for addicts who initiate abstinence while in treatment, a high percentage relapse within the year immediately following treatment.

In one experiment, Dr. Greenwald identified about a dozen “hardcore” heroin addicts who spent at least $40 per day on the drug. The addicts were placed on the heroin substitutes methadone or buprenorphine, and had to report for urinalysis three times a week. Their levels of methadone and buprenorphine were decreased over the course of several weeks. If they tested negative for heroin use for consecutive days, they received a check for $30. The majority of those who received the payment for remaining “clean” stayed off of heroin longer, even though their physical environment and acquaintances did not change.

While he said more testing remains to be done, Dr. Greenwald believes that the $30 “reward” somehow became more valuable in the minds of the addicts than the need for heroin or a substitute.

These initial short-term findings, Dr. Greenwald said, may lead to tailored treatment for addicts. Some may need a shorter course of rehabilitation and contact with those providing treatment to successfully abandon their drug habit. Others may be identified in the opening rounds of rehabilitation as needing more intensive treatment or longer contact with healthcare providers for successful rehabilitation.

“We can provide more flexible treatment, offer more support, for those who require it,” said Dr. Greenwald. “This could be the basis to combat, in the initial offing, someone who is at high risk for relapse. We should not abruptly cut somebody off from treatment if we know they may be predisposed to go back to the drug.”

The knowledge that Dr. Greenwald hopes to discover “may give us the means to provide a softer landing for those more susceptible to relapse,” he said. “Even if addicts fail, they are more likely to be successful over the long run if they keep trying. Any help we can provide is key to that success. We need to begin thinking about addiction as a chronic disease, almost like diabetes or hypertension.”

Dr. Greenwald also is conducting brain scan studies that relate the presence and amount of glutamate in the brain in relation to addiction relapse. Levels of glutamate, an excitatory amino acid neurotransmitter, may serve as an indicator of someone more prone to relapse once they are addicted to a substance.

While Dr. Greenwald focuses on opiates like heroin and cocaine, his research may hold the promise of similar results for addictions to other substances, like alcohol and nicotine.

The potential successes such research holds is greater than that of an individual kicking a habit, Dr. Greenwald said. The cost of drug addiction to society must also be measured in crime rates, incarceration, emergency room use and the spread of disease through shared needles or the trading of sexual acts for money to purchase illicit drugs.

One obstacle hampering continued research is funding. National Institutes of Health funding is in short supply, and sustaining such research over the long term is challenging, Dr. Greenwald admitted. He is in the process of writing an NIH grant application for $1.6 million over a four-year period to continue ongoing research into glutamate levels through magnetic resonance spectroscopy.