Baclofen Can Cut Cocaine Cravings

The use of baclofen can block the impact of the brain’s response to unconscious drug triggers and reduce the likelihood of relapse, according to research published in the Journal of Neuroscience.

Researchers from the Perelman School of Medicine at the University of Pennsylvania tested baclofen, which is commonly used to treat spasms in spinal cord injury patients, on 23 cocaine-dependent men aged 18 to 55 years. The participants reported using cocaine for at least 8 out of the previous 30 days prior to the start of the study. The men were required to stay in a supervised inpatient drug treatment facility for 10 days, be drug-free for the duration of their stay, not be on medication impairing dopamine or neurotransmitter response, and have no history of psychosis, seizures, or brain syndromes unrelated to cocaine use.

For the first 6 days, 12 men received baclofen in increasing doses up to 60 mg. While on the full 60 mg dose, patients were given an fMRI screening and shown a series of images to measure their responses to “ultra-brief” pictures of cocaine and other images for comparison. Each cocaine picture lasted 33 msec and was immediately followed by a longer picture of non-drug objects or scenes. Patients were aware of the longer pictures in this process, but the target images remained outside the conscious awareness, something the researchers called “backward-masked.”

“We wanted to present the key stimulus: images of drug use and preparation, sexual images, and other aversive images in a way such that the brain could not consciously process them, but so that we could measure their earliest, subconscious effect on the brain,” Anna Rose Childress, PhD, senior author of the study, said in a press release.

The remaining 11 men were given a placebo for the duration of their stay. The scientists found the men treated with baclofen showed significantly reduced response in the reward and motivational brain circuits to subliminal cocaine versus neutral cues compared to the placebo group. The researchers noted that the stimulant response was reduced solely for drug-related cues, as no difference was seen in the active sexual and aversive cues.

“Drug reward and motivation is largely mediated by dopamine transmission in the brain’s reward circuit—even drug ‘reminder cues’ can cause dopamine release,” Kimberly Young, PhD, first author on the study, explained in a press release. “Since baclofen and similar medications reduce these effects in laboratory animals, we wanted to examine whether it could prevent drug-cue induced activation in the human brain. These findings suggest that the brain response to drug cues presented outside of awareness can be pharmacologically inhibited, providing a mechanism for baclofen’s potential therapeutic benefit in addiction.”