Bilateral transcranial magnetic stimulation of the prefrontal cortex reduces cocaine intake: A pilot study

Background: Chronic cocaine consumption is associated with a decrease in mesolimbic dopamine transmission that maintains drug intake. transcranial magnetic stimulation (TMS) is gaining reliability, a useful therapeutic tool in drug addiction, since it can modulate cortico-limbic activity resulting in reduction of drug craving. Aims: In the present study, we investigated the therapeutic effect of bilateral TMS of prefrontal cortex (PFC) in reducing cocaine intake, in a sample of treatment-seeking patients with current cocaine use disorder (DSM-V). Methods: Ten cocaine addicts (DSM-V) were randomly assigned to the active or sham stimulation protocol in a double-blind experimental design. Twelve repetitive TMS (rTMS) sessions were administered three times a week for 4 weeks at 100% of motor threshold, over bilateral PFC. Cocaine intake (ng/mg) was assessed by hair analysis at baseline (before treatment, T0), after 1 month (end of treatment, T1), 3 (T2), and 6 (T3) months later. All subjects received psychological support weekly. Results: The two-way ANOVA for repeated measures did not show a significant effect of the interaction between time and treatment (F4,32 = 0.35; p = 0.87). Despite that result indicated no difference in the effect of the two conditions (active vs. sham) along time, a decreasing trend in cocaine consumption in active TMS group (F3,23 = 3.42; p = 0.04) vs. sham (F3,15 = 1.88; p = 0.20) was observed when we performed exploratory analysis with time as factor. Indeed, Post hoc comparisons showed a significant reduction in the amount of cocaine detected from the onset to 3 months later (T0-T2; p = 0.02) and to the end of treatment (T0-T3; p = 0.01) in addicts from the active group. Conclusion: Bilateral rTMS of PFC at 10 Hz did not show a significant effect on cocaine intake compared to sham. However, a long-term reduction on cocaine intake in active TMS-treated patients was observed when we considered the time as factor. Further studies are required to confirm these encouraging but preliminary findings, in order to consolidate rTMS as a valid tool to treat cocaine addiction.