Brain stimulation as an emerging treatment for addiction

A wealth of preclinical research has shown that altering activity in frontostriatal circuits can modulate drug-taking behavior. The challenge now is to translate these basic science discoveries into a safe and effective treatment for our patients. This chapter will introduce transcranial magnetic stimulation (TMS) as a noninvasive brain stimulation tool that is currently being used to advance therapeutic options for patients with substance use disorders. As this field develops, the primary questions will likely be (1) what cortical location should we target to maximally affect the circuitry we are interested in changing? and (2) what stimulation frequency should we choose? From the perspective of addiction, it is possible to differentially activate frontostriatal circuits involved in limbic control from those involved in executive control through stimulating the medial prefrontal cortex (MPFC) and the dorsolateral prefrontal cortex (DLPFC), respectively. The data presented in this chapter demonstrate that while most of the efforts for rTMS in addiction have been focused on increasing activity in the DLPFC, decreasing activity in the MPFC and ventral striatum may also be a feasible and fruitful target to consider. It seems plausible that either increasing neural firing in the executive control circuit (via high-frequency TMS in the DLPFC) or decreasing firing in the limbic circuit in the presence of cues (via low-frequency TMS in the MPFC) may be valuable strategies for decreasing vulnerability to drug-related cues. Before moving forward with slow and expensive clinical trials, it is important to have a comprehensive understanding of limbic and executive circuit modulation in a diverse cross section of substance-dependent individuals.