Many individuals who enter drug abuse treatment for cocaine addiction experience a frustrating cycle of recovery and relapse. In fact, the National Institute on Drug Abuse reports that 40 to 60 percent of those who receive treatment for addiction will relapse. At six months following treatment, the rates can climb to 80 percent.
In treatment, many strategies use therapies designed to train the patient to recognize cues and stimuli that spark cravings. Patients learn how to handle these triggers in the treatment environment in order to prepare for real-life experiences. However, many patients find that they relapse before they are able to identify the source of their temptation.
In a study conducted by researchers at the University of Pennsylvania, investigators tested the use of a drug to stave off relapse. The medication is one that is commonly used to treat spasms in patients with spinal cord injuries or neurological disorders.
The researchers from Penn Medicine’s Center for Studies on Addiction tested the drug baclofen to see if it would block the brain’s response to unconscious drug triggers before a craving led to drug use. The findings appear in the Journal of Neuroscience.
Senior author Anna Rose Childress, Ph.D., explains that the study was designed to address the challenges faced by patients who reported a moment of “volcanic craving,” in which they were suddenly overcome with cravings, but without any warning in the form of a trigger that could be identified. Childress is a research professor of Psychiatry and the director of the Brain-Behavioral Vulnerabilities Division in the Perelman School of Medicine at the University of Pennsylvania.
In their previous work, Dr. Childress and colleagues had found that there were subliminal “reminder cues” that led to the activation of the brain’s reward system, which resulted in a relapse. The researchers wanted to find out in the current study if a medication would be able to inhibit the response in the brain and prevent relapse.
First author of the study, Kimberly Young, Ph.D., an NIH/NIDA post-doctoral fellow at Penn, said that dopamine transmission is at the center of the brain’s reward process. Even drug cues can lead to dopamine release. Earlier studies had shown that baclofen was effective at reducing the dopamine release in animal models, so the researchers wanted to test whether they would see the same effects in human participants.
The medication was tested in 23 cocaine-dependent men between ages 18 and 55. To qualify for the study, the men had to be using cocaine a minimum of eight out of the past 30 days prior to the screening. The patients were also required to stay in a supervised inpatient treatment program and to be drug-free during their stay.
The patients were given baclofen or a placebo, with dosage of the baclofen increasing to 60 mg over a period of six days initially. Once the full dosage was in place, the patients were positioned in an fMRI to view images while the researchers measured their neural responses to the ultra-brief exposure.
The pictures of cocaine were 33 milliseconds long, followed by a lengthier picture of non-drug objects of scenes. The short pictures were outside of the conscious awareness, called a “backward-masked” image.
The researchers were able to measure the earliest possible effects on the brain with the backward-masked images.
The researchers found that the patients treated with baclofen exhibited a lower response to the motivational and reward cues in subliminal images versus when they observed the neutral cues, when compared to those in the placebo group. In addition, no differences were measured in the two groups when they were viewing aversive and sexual cues, showing that the effects of the baclofen were specific to drug cues.