A systematic review of randomised controlled trials has found evidence that non-invasive brain stimulation may reduce smoking frequency – the number of cigarettes per day – in nicotine-dependent smokers. The study by an international team of researchers was published last week in the journal Addiction.
This is according to material produced by the Society for the Study of Addiction and published on 4 August 2021. The material runs below, along with the Addiction abstract. The researchers are from Taiwan, the United Kingdom, Australia and Brazil.
Because nicotine can produce neuroadaptations in the brain that make it hard to quit smoking, researchers have sought ways to treat nicotine dependence with non-invasive brain stimulation (NIBS) techniques that counteract abnormal brain activity associated with chronic nicotine exposure.
The review looked at 12 randomised controlled trials of NIBS methods on a combined total of 710 participants with nicotine dependence. It used a network meta-analysis technique to compare the benefits and safety of various types of NIBS.
Several NIBS techniques showed promising results, but the best results came from high-frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal (DLPFC), which was associated with the greatest reduction in smoking frequency.
Interestingly, none of the investigated NIBS appeared to reduce the severity of either craving or nicotine dependence, compared with the control groups. It may be that enhancement of DLPFC activity increases dopamine release, counterbalances the reward system, and helps patients cope with unaffected craving and withdrawal symptoms.
None of the investigated NIBS was associated with dropout rates significantly different from those of the control groups, suggesting that these kinds of treatments are well tolerated.
Nicotine affects the release of neurotransmitters in the brain, increasing brain activity and the release of dopamine. Higher levels of dopamine bring pleasure to the smoker.
Over time, chronic nicotine exposure causes the brain to produce more receptors to handle the increased brain activity. When nicotine levels drop, such as when a smoker tries to quit, activity in the brain's reward system decreases, causing withdrawal symptoms that encourage continued smoking.
Efficacy of non-invasive brain stimulation interventions in reducing smoking frequency in patients with nicotine dependence: a systematic review and network meta-analysis of randomized controlled trials
Ping-Tao Tseng, Jia-Shyun Jeng, Bing-Syuan Zeng, Brendon Stubbs, Andre F. Carvalho, Andre R. Brunoni, Kuan-Pin Su, Yu-Kang Tu, Yi-Cheng Wu, Tien-Yu Chen, Pao-Yen Lin, Chih-Sung Liang, Chih-Wei Hsu, Yen-Wen Chen and Cheng-Ta Li
Author affiliations: The researchers are from numerous institutions in Taiwan as well as National Sun Yat-sen University, Asia University, China Medical University, National Taiwan University, National Yang Ming Chiao Tung University, National Central University and Chang Gung University College of Medicine. Other researchers are from King's College London and Anglia Ruskin University in the United Kingdom; Deakin University in Australia; and the University of Sao Paulo in Brazil.
Published in the journal Addiction on 4 August 2021.
Nicotine is a highly addictive substance in tobacco products that dysregulates several neurotransmitters in the brain and impairs executive function. Non-invasive brain stimulation (NIBS) methods such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are promising treatments for nicotine dependence.
We investigated the efficacy and acceptability of NIBS in managing smoking cessation through a systematic review and network meta-analysis (NMA).
We conducted a systematic review to identify randomized controlled trials (RCTs) that investigated the efficacy of NIBS for smoking cessation. All pairwise meta-analyses and NMA procedures were conducted using random-effects and frequentist models.
The co-primary outcomes were (1) the change in number of cigarettes smoked per day (change in frequency of smoking) in patients with nicotine dependence after NIBS and (2) acceptability (the dropout rate).
The effect sizes for co-primary outcomes of change in frequency of smoking and acceptability were assessed according to standardised mean difference (SMD) and odds ratio, respectively.
Twelve RCTs with 710 participants (mean age: 44.2 years, 31.2% female) were included. Compared with the sham control, 10-Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) was associated with the largest changes in smoking frequency [SMD = −1.22, 95% confidence interval (95% CI) = −1.77 to −0.66]. The 2-mA bifrontal tDCS (SMD = −0.97, 95% CI = −1.32 to −0.62) and 10-Hz deep rTMS over the bilateral DLPFC with cue provocation (SMD = −0.77, 95% CI = −1.20 to −0.34) were associated with a significantly larger decrease in smoking frequency versus the sham.
None of the investigated NIBSs was associated with dropout rates significantly different from those of the sham control groups.
Prefrontal non-invasive brain stimulation interventions appear to reduce the number of cigarettes smoked with good acceptability.
Addiction journal article – Efficacy of non-invasive brain stimulation interventions in reducing smoking frequency in patients with nicotine dependence: a systematic review and network meta-analysis of randomized controlled trials (Open access)
See also from the MedicalBrief archives