Non-invasive vagus nerve stimulation for substance use disorder: A narrative review.

BACKGROUND

Recent technological advances have led to increased experimentation in non-invasively modulating the brain to reduce craving and drug use in substance use disorder (SUD). However, many forms of neuromodulation remain costly and require administration in a medical setting, limiting scalability. Vagus nerve stimulation (VNS) circumvents these limitations. A substantial body of neurobiological and clinical evidence suggests that VNS may be well-suited to target core mechanisms underlying substance use, including craving, mood, and stress dysregulation.

METHODS

Fifty-two searches with terms related to VNS and SUD were used to find papers reporting results on the use of non-invasive VNS in SUD. Data were extracted to tables and collated for a narrative review.

RESULTS

Eleven publications were found (eight unique trials) in individuals with opioid or alcohol use disorder. No investigations into other substances were identified. Outcomes range from acute withdrawal to longer-term reduction of craving and depression. Studies differ in outcomes, stimulation location (auricular or cervical), parameters, laterality, and number and length of sessions. Despite methodological variation, studies provide preliminary evidence that non-invasive VNS may be feasible, safe, and capable of modulating withdrawal-related, affective, and autonomic outcomes, though current evidence for craving reduction is limited and inconsistent.

CONCLUSIONS

Increasing sample sizes, reporting on sex-differences, and including randomized-sham controlled designs in a wider range of SUDs is critical to conclusively determine the utility of VNS for SUD. As with other neuromodulation techniques, maintaining consistency with device parameters and reporting is needed to enhance standard of care.