Effects of single-session versus multi-session non-invasive brain stimulation on craving and consumption in individuals with drug addiction, eating disorders or obesity: A meta-analysis

Background: Brain stimulation interventions are increasingly used to reduce craving and consumption in individuals with drug addiction or excessive eating behavior. However, the efficacy of these novel treatments and whether effect sizes are affected by the length of the intervention has not been comprehensively evaluated. Objective: A meta-analytical approach was employed to evaluate the effectiveness of non-invasive excitatory brain stimulation [transcranial Direct Current Stimulation (tDCS) and high-frequency repetitive Transcranial Magnetic Stimulation (rTMS)] targeted at dorsolateral prefrontal cortex (dlPFC) for reducing craving and consumption levels in drug and eating addiction, including both single- and multi-session protocols. Methods: After a comprehensive literature search, 48 peer-reviewed studies (1095 participants in total) were included in the current meta-analysis. We computed Hedge's g as a conservative measure for evaluating effect sizes. Results: Random effects analyses revealed a small effect of neuromodulation interventions on craving and a medium effect on consumption, favoring active over sham stimulation. These effects did not differ across the different populations investigated (alcohol, nicotine, illicit drugs, eating addictions) or by the used technique (rTMS/tDCS, left/right hemisphere). Multi-session protocols showed a larger effect size for reducing craving and consumption than single-session protocols, with a positive linear association between the number of sessions or administered pulses and craving reduction, indicating a dose-response effect. Conclusions: Our results provide compelling evidence that novel non-invasive brain stimulation targeted at dlPFC reduces craving and consumption levels (providing the first meta-analytical evidence for the latter effect in drug addiction), with larger effects in multi-session as compared to single-session interventions.