SAR-161206-transcranial-magnetic-stimulation-for-the-treatment-of-cocai_051818.pdf

Tion paradigms studies differed in both coil employed

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tion paradigms, studies differed in both coil employed and parameters adopted. The majority of rTMS studies in CUD have used the figure-of-8 coil to target the DlPfCx (left side), a central node in the frontostriatal network whose functional- ity is inhibited in addiction disorders. 8,9 Cortical dysfunction may account at least in part for the impaired executive con- trol that is required to resist drug-related stimuli and cease drug-seeking behavior. For this reason, papers reviewed here aimed at prefrontal brain regions, in order to enhance cortical activity, improve behavioral control, and through this inhibit drug intake. From a neurobiological perspective, the clinical beneficial effects of TMS over DlPfCx are supported by the evidence, which demonstrated the enhancement of dopami- nergic activity in the midbrain (nucleus accumbens), which is depressed in addiction. 64,65–99 Two studies implemented the H-coil in the treatment of cocaine addiction, finding a significant reduction in craving and intake. 86,87 However, only one study considered the sham group, reporting a lasting reduction in cocaine intake, but no difference between the real and the control groups. 87 The small sample, however, does not permit any firm conclusion on the efficacy of rTMS in the treatment of cocaine addiction, but results are nevertheless encouraging and foster future investigations. Another study changed the theoretical model by using bursts of pulses (cTBS) over the MPfCx. 92 This new model started from the hypothesis that the MPfCx is the primary cortical input to the ventral striatum, a central node in elaborating the salience of drug-related stimuli and the motivation/drive for drug seeking. This hypothesis is supported by a previous study, which demonstrated that LTP-like (10 Hz) rTMS to the MPfCx in a group of eleven healthy non-drug-using subjects was associated with a significant reduction in DA-binding potential in the dorsal striatum, reflecting a release of DA in these areas. 98 Despite the small sample, this new approach could provide a novel efficacious strategy to target the areas involved in craving for cocaine, and reiterates the key role played by impoverished DA transmission in these effects. 22 The frequency of stimulation observed in the studies revised was 10–20 Hz, with one to 12 sessions. The inten- sity of stimulation, varied from 90% to 120% of MT. In all studies, the targeted area was identified through scalp landmarks, and only one study used neuronavigation to enhance accuracy in targeting the selected brain region to be stimulated. 85,99 The total number of pulses, a key factor in stimulation efficacy, varied and comprised between 600 and 2,400 pulses/session. 100–102 For these reasons, all studies reviewed implemented a repetitive-stimulation protocol for several sessions, and this is one of the areas that should be investigated further in future studies to achieve long-lasting effects.
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