Transcranial electrical and magnetic stimulation (tES and TMS) for addiction medicine: A consensus paper on the present state of the science and the road ahead

There is growing interest in non-invasive brain stimulation (NIBS) as a novel treatment option for substance-use disorders (SUDs). Recent momentum stems from a foundation of preclinical neuroscience demonstrating links between neural circuits and drug consuming behavior, as well as recent FDA-approval of NIBS treatments for mental health disorders that share overlapping pathology with SUDs. As with any emerging field, enthusiasm must be tempered by reason; lessons learned from the past should be prudently applied to future therapies. Here, an international ensemble of experts provides an overview of the state of transcranial-electrical (tES) and transcranial-magnetic (TMS) stimulation applied in SUDs. This consensus paper provides a systematic literature review on published data - emphasizing the heterogeneity of methods and outcome measures while suggesting strategies to help bridge knowledge gaps. The goal of this effort is to provide the community with guidelines for best practices in tES/TMS SUD research. We hope this will accelerate the speed at which the community translates basic neuroscience into advanced neuromodulation tools for clinical practice in addiction medicine.

Accelerated repetitive transcranial magnetic stimulation does not influence grey matter volumes in regions related to alcohol relapse: An open-label exploratory study

The application of repetitive transcranial magnetic stimulation (rTMS) to prevent relapse in alcohol addiction is currently being evaluated. However, how rTMS may influence the related brain processes is far from clear. Here we wanted to investigate whether baseline grey matter volume (GMV) can predict relapse and whether 15 accelerated high-frequency (HF)- rTMS sessions may influence GMV in areas related to relapse. Voxel-based morphometric (VBM) measurements were used to compare baseline GMV of 22 detoxified, hospitalized, alcohol-dependent patients with 22 age and gender matched healthy control subjects. Only patients received 15 accelerated HF-rTMS sessions at the right dorsolateral prefrontal cortex (DLPFC) followed by VBM measurements. Relapse rates were assessed four weeks after the end of the stimulation protocol. At baseline, alcohol-dependent patients overall showed less GMV in diffuse brain areas compared to healthy controls. Relapsers compared to abstainers displayed larger GMV decreases, especially in brain midline structures, insular, hippocampal, and amygdalar areas. Accelerated HF-rTMS treatment had no significant effect on GMV in alcohol-dependent patients, regardless of the relapse state. Although an accelerated HF-rTMS treatment protocol did not influence GMV in alcohol-dependent patients, baseline GMV predicted future relapse.

[Clinical effects of non-invasive neuromodulation techniques in substance use disorder: an overview]

BACKGROUND

Substance dependence is a chronic disorder that is difficult to treat. Non-invasive stimulation techniques may have beneficial effects on the course of the illness.

AIM

To provide an overview of studies that evaluate the clinical effects that transcranial magnetic stimulation (tMS) and transcranial direct current stimulation (tDCS) have on patients with substance use disorders.

METHOD

We performed an extensive search of the literature, using PubMed.

RESULTS

Most studies showed that both tMS and tDCS have a beneficial effect on clinical outcomes. However, the effects seemed to wear off over time, even if tMS and tDCS had been administered to patients over several sessions.

CONCLUSION

In terms of efficacy, we award a level B qualification to both tMS and tDCS, which means that we regard both techniques as 'very probably efficient'.

Accelerated HF-rTMS Protocol has a Rate-Dependent Effect on dACC Activation in Alcohol-Dependent Patients: An Open-Label Feasibility Study

BACKGROUND

The application of accelerated high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) could be a potential treatment option for alcohol-dependent patients and may result in a faster clinical response. In this open-label HF-rTMS feasibility study, we wanted to replicate previous findings of baseline brain activation as a predictor of relapse, and to evaluate how this intervention influences the relapse neurocircuit of "treatment-seeking" alcohol-dependent patients, by means of functional magnetic resonance imaging (fMRI) cue-exposure paradigms. Because relapsing patients have a diminished resilience of the emotion regulation/cognitive control system, before HF-rTMS treatment, we expected lower neuronal activation of especially the ventromedial prefrontal cortex and anterior cingulate cortex (ACC) during the presentation of alcohol-related cues in these patients. The relapse neurocircuit should be modified after accelerated HF-rTMS treatment, only in those patients who did not relapse.

METHODS

After being administered a single sham-controlled HF-rTMS session (20 Hz to 110% motor threshold), 19 alcohol-dependent patients received an accelerated HF-rTMS protocol, consisting of 14 right dorsolateral prefrontal cortical sessions spread over 3 days. Before and after stimulation, during fMRI patients were confronted with a block and an event-related alcoholic cue-exposure paradigm. Relapse was defined as the consumption of any amount of alcohol within 4 weeks after the stimulation. A region of interest analysis was performed to evaluate how HF-rTMS exerts its effect.

RESULTS

After 4 weeks, 13 of 19 patients had already consumed alcohol. When abstainers were compared to patients who had relapsed, we found higher dorsal ACC (dACC) activation at baseline, but only during the blocked cue-exposure paradigm. The effects of HF-rTMS on dACC blood oxygen level-dependent response were negatively correlated with the baseline dACC activation. Due to susceptibility artifacts located at the ventral cortical aspects in 6 of our participants, reliable data were only obtained for the ACC.

CONCLUSIONS

Our data indicate that higher baseline dACC activation may serve as a protective mechanism regarding relapse. For the first time, it is demonstrated that accelerated HF-rTMS treatment influences dACC activation in a rate-dependent manner: the lower the baseline dACC activation, the more dACC activity was increased after HF-rTMS treatment.

Reduced intra-individual reaction time variability during a Go-NoGo task in detoxified alcohol-dependent patients after one right-sided dorsolateral prefrontal HF-rTMS session

AIMS

As alcohol dependency is characterized by severe executive function deficits, we examined the influence of high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) applied to the right dorsolateral prefrontal cortex (DLPFC) on executive functioning in recently detoxified alcohol-dependent patients.

METHODS

In this randomized, single blind, sham (placebo)-controlled, crossover study, we included 50 detoxified alcohol-dependent patients. We examined the effect of a single right DLPFC HF-rTMS session on commission errors, mean reaction times (RTs) and intra-individual reaction time variability (IIRTV) during a Go-NoGo task (50% Go/50% NoGo condition) in 29 alcohol-dependent patients. Patients completed this cognitive task immediately before and immediately after the stimulation session. In order to avoid carry-over effects between stimulation sessions, a 1-week inter-session interval was respected. Because rTMS treatment has been shown to affect subjective craving, all patients were also assessed with the Obsessive Compulsive Drinking Scale (OCDS).

RESULTS

After both stimulation conditions, we observed a significant decrease of commission errors, without differences between active and sham HF-rTMS stimulation. No significant difference was observed between active and sham stimulation on mean RT. However, only active stimulation resulted in a significant decrease in IIRTV. No effects of stimulation were found for the craving measurements.

CONCLUSION

Our findings suggest that in recently detoxified alcohol-dependent patients, one right-sided HF-rTMS session stabilizes cognitive performance during executive control tasks, implying that active stimulation reduces patients' proneness to attentional lapses.

The current perspective of neuromodulation techniques in the treatment of alcohol addiction: a systematic review

BACKGROUND

Alcohol dependency can be considered as a chronic mental disorder characterized by frequent relapses even when treated with appropriate medical or psychotherapeutic interventions. Here, the efficacy of different neuromodulation techniques in alcohol addiction, such as transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), deep brain stimulation (DBS), vagal nerve stimulation (VNS) and electroconvulsive therapy (ECT) is critically evaluated.

METHODS

A broad literature search on electronic databases such as NCBI PubMed, the Web of Knowledge, the Cochrane Library was conducted. Additionally, we searched recent handbooks on neuromodulation and/or addiction.

RESULTS

Studies investigating these neuromodulation techniques in alcohol addiction remain to date rather limited and especially tDCS and rTMS applications have been investigated. Overall, the clinical effects seem modest. The use of VNS and ECT has yet to be investigated in alcohol dependent patients.

CONCLUSIONS

Neuromodulation techniques have only recently been subject to investigation in alcohol addiction and methodological differences between the few studies restrict clear-cut conclusions. Nevertheless, the scarce results encourage further investigation in alcohol addiction.

No influence of one right-sided prefrontal HF-rTMS session on alcohol craving in recently detoxified alcohol-dependent patients: results of a naturalistic study

BACKGROUND

Prior research in substance dependence has suggested potential anti-craving effects of repetitive transcranial magnetic stimulation (rTMS) when applied to the dorsolateral prefrontal cortex (DLPFC). However, no single sham-controlled session studies applied to the right DLPFC have been carried-out in recently detoxified alcohol-dependent patients. Furthermore, no studies examined the effect of a single HF-rTMS session on craving in these patients' natural habitat.

METHODS

To further investigate the effect of high-frequency (HF)-rTMS of the right DLPFC on alcohol craving, we performed a prospective, single-blind, sham-controlled study involving 36 hospitalized patients with alcohol dependence syndrome. After successful detoxification, patients were allocated receiving one active or one sham HF-rTMS session. The obsessive-compulsive drinking scale (OCDS) was administered to evaluate the extent of craving just before and after the HF-rTMS session (on Friday), on Saturday and Sunday during the weekend at home, and on Monday when the patient returned to the hospital.

RESULTS

One single blind sham-controlled HF-rTMS session applied to the right DLPFC did not result in changes in craving (neither immediately after the stimulation session, nor in patients' natural environment during the weekend).

CONCLUSIONS

One HF-rTMS stimulation session applied to the right DLPFC had no significant effects on alcohol craving in alcohol dependent patients. One such session could have been too short to alter alcohol craving in a sample of alcohol dependent patients.