Researchers first performed a literature search of the MEDLINE and Cochrane databases for randomized, controlled trials and controlled clinical trials on transcranial magnetic stimulation (TMS) in patients with substance use disorder published up until 2015. Ten studies met the authors’ criteria for inclusion in the meta-analysis, including six on alcohol use disorder and four on nicotine use disorder that involved TMS stimulation to regions of the prefrontal cortex.
The meta-analysis revealed a significant effect size favoring active rTMS stimulation over sham stimulation in reducing craving in substance dependence. Active rTMS stimulation was found to be highly effective for nicotine use disorder in subgroup analysis, but it showed no favorable effect for alcohol use disorder.
“Stimulating DLPFC [dorsolateral prefrontal cortex] by rTMS has been postulated to reduce substance craving possibly by two mechanisms. ... [I]nterconnections of the DLPFC with the ventral tegmental area (VTA) increase dopamine excretion from the VTA to the ventral striatum, an area implicated in reward processing. ... [S]timulation of the DLPFC stimulates glutamate containing corticofugal fibers, which end on dopamine containing terminals in the ventral striatum, potentially increasing dopamine excretion and reducing craving,” wrote Rituparna Maiti, M.D., and colleagues at the All India Institute of Medical Sciences (AIIMS) in Bhubaneswar, India.
Based on the results of the meta-analysis, Maiti and colleagues recommended the adoption of a uniform rTMS treatment protocol for patients with nicotine use disorder. They also called for additional trials to examine the effectiveness of rTMS in patients with alcohol use disorder. “There is a need for further clinical trials with robust rTMS protocols and a greater number of treatment sessions to make a final conclusion on the anti-craving effects of rTMS in alcohol use disorder,” they concluded.
For related information, see the Psychiatric News article “Neuromodulation May Benefit Patients With Varying Psychiatric Illnesses,” by Andrew Leuchter, M.D., director of the Neuromodulation Division at the Semel Institute for Neuroscience and Human Behavior at the David Geffen School of Medicine at the University of California, Los Angeles.