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“Although an anti-craving effect of rTMS intervention has been indicated by previous literature, the effect of different rTMS protocols on craving and substance consumption and the association between stimulation parameters and effect sizes has not been systematically investigated,” Jack J.Q. Zhang, M.Sc., of The Hong Kong Polytechnic University and colleagues wrote.
Zhang and colleagues analyzed data from 26 studies published between January 2000 and October 2018 to determine which ways of using rTMS yield the best results for curbing cravings and substance use. The studies involved 748 participants with alcohol, nicotine, or illicit drug dependence and compared the effect of active rTMS with sham (fake) stimulation. Participants reported their cravings and substance use via tools such as questionnaires at various points in the studies.
They found that stimulation of the left dorsolateral prefrontal cortex (DLPFC), located toward the top left side of the brain, significantly reduced cravings in participants who received active treatment compared with those who received sham treatment. Treatment of the left DLPFC appeared to be more effective in reducing cravings in participants who were dependent on illicit drugs (such as cocaine and heroin), than in those with nicotine or alcohol dependence. rTMS of the right DLPFC had no significant effect on cravings in participants who received active treatment compared with those who received sham treatment.
Treatment involving stimulation of the left DLPFC reduced substance use in participants who received active treatment, as well. Treatments involving bilateral stimulation (both the left and right) of the DLPFC and another part of the brain called the insula also curbed substance use.
The researchers noted that the positive effects of rTMS appeared to be short-lived and often wore off by follow-up (on average, four months later).
“Our results … highlight the need to optimize intervention parameters and to increase the durability of the anti-craving and consumption-reducing effects [of rTMS],” they concluded.
For related news, see the Journal of Neuropsychiatry and Clinical Neurosciences article “Outcome of Non-Invasive Brain Stimulation in Substance Use Disorders: A Review of Randomized Sham-Controlled Clinical Trials.”
(Image: iStock/Hank Grebe)
