How deep is the deep Transcranial Magnetic Stimulation(dTMS)? Putative stimulation ofreward pathwaysinsubstanceuse disorders: A systematicreviewandmeta-analysis

Background:

Deep transcranial magnetic stimulation (DTMS) is a non-invasive method of stimulating widespread cortical areas and presumably deeper neural networks.

Objective:

The current study assessed the efficacy of DTMS in the treatment of substance use disorders (SUD) using a systematic review and meta-analysis.

Methods:

Following a systematic literature search of PsycInfoand Medline (any date till August 2016), k=5 open-label studies and k=3 double-blind, randomised sham-controlled trials were included in the review. Short-term (acute) and longer-term (at the last follow-up) efficacy was measured as craving (Obsessive Compulsive Drinking Scale, OCDS; Visual Analogue Scale for Craving, VAS), dependence (Fagerstrom Test for Nicotine Dependence, FTND), or consumption (use frequency, abstinence rate, biological test outcomes).

Results:

A random-effects meta-analysis revealed a large pooled reduction in craving (for alcohol and cocaine) and dependence (for nicotine) after an acute treatment with DTMS relative to baseline (Hedges’g=2.65, 95% confidence interval, 95% CI: 1.28-4.02, p<.001, k=5 studies, n=53 participants, I2=85%). A qualitative synthesis showed that high-frequency (18-20 Hz) and high-intensity (120% of the resting motor threshold, MT) DTMS reduced alcohol craving particularly in patients with comorbid alcohol use disorder (AUD) and a major depressive disorder in the short-term (after 20 sessions) and at 6-12 months follow-up. Cocaine craving was reduced after12 sessions of DTMS (15 Hz, 100% MT) and both craving and consumption were reduced at 2-6 months follow-up respectively. Nicotine consumption (but not craving) was reduced after 13 sessions of DTMS (10 Hz, 120% MT) and at 6-months follow-up.

Conclusions:

Acute improvements in various symptoms of SUD after high-frequency DTMS could be due to changes in activity of the cortico-mesolimbic pathways and neural regions involved in control of reward-mediated behaviour. Repetitive stimulation might induce changes in neuroplasticity which could contribute to the longer-term effects of DTMS on SUD without maintenance treatment.

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