TMS for the functional evaluation of cannabis effects and for treatment of cannabis addiction: A review

The knowledge about the effects of cannabis on human cortical brain processes is increasing. In this regard, transcranial magnetic stimulation (TMS) enables the evaluation of central nervous system function, including drug effects. Moreover, repetitive TMS (rTMS) has been used therapeutically in several substance use disorders. In this scoping review, we summarize and discuss studies that have employed TMS and rTMS techniques in users of cannabis for recreational purposes. In subjects with a history of persistent cannabis use, TMS studies showed reduced short-interval cortical inhibition (SICI). This observation points more at neurobiological changes of chronic cannabis use than to a direct effect of cannabis on gamma-aminobutyric acid (GABA) A receptors. Moreover, individuals vulnerable to becoming long-term users of cannabis may also have underlying pre-existing abnormalities in SICI. Of note, the use of cannabis is associated with an increased risk of schizophrenia, and the down-regulation of GABAergic function may play a role. Less frequent cannabis use and spontaneous craving were observed following rTMS applied to the dorsolateral prefrontal cortex (DLPFC). There is emerging evidence that the posterior cingulate cortex and the precuneus are potential targets for rTMS intervention in cannabis use disorder. However, larger and randomized trials should corroborate these encouraging findings.

Automated summary

The effects of cannabis on human cortical brain processes can be evaluated through transcranial magnetic stimulation (TMS). Persistent cannabis use is associated with reduced cortical inhibition, indicating neurobiological changes. Individuals vulnerable to long-term use may have pre-existing cortical inhibition abnormalities. Cannabis use is also linked to an increased risk of schizophrenia, possibly due to down-regulation of GABAergic function. Repetitive TMS applied to the dorsolateral prefrontal cortex (DLPFC) can result in less frequent cannabis use and craving. The posterior cingulate cortex and the precuneus show potential as targets for rTMS intervention in cannabis use disorder.