Evidence-based umbrella review of non-invasive brain stimulation in anxiety disorders

Background and objectives Although several meta-analyses have suggested the efficacy of non-invasive brain stimulation (NIBS) mainly in prefrontal brain areas to treat mental disorders, no synthetic approach has been performed for other psychiatric disorders rather than depression. The objective is to assess the available evidence of NIBS in the treatment of anxiety disorders. Methods An umbrella review (CRD42021239577) was performed only looking for reviews with meta-analyses of randomized clinical trials using a source strategy MeSH keywords in MEDLINE through Pubmed by two independent researchers. The effects of different methods of NIBS in anxiety disorders were assessed using the PICO strategy. The methodological quality was evaluated using AMSTAR-2 and certainty of evidence using the GRADE-pro framework. Results From 136 screening meta-analyses, 16 from 14 studies were included in the final analysis. Generalized Anxiety Disorder (GAD) and Obsessive Compulsive Disorder (OCD) respond best to low frequency repetitive transcranial magnetic stimulation (rTMS), while Posttraumatic Stress Disorder (PTSD) has the largest effect size at high frequency rTMS. Panic Disorder (PD) has no evidence for clinical use of NIBS. There were not identified meta-analyses about other anxiety disorders. In general, the included studies had good methodological quality, but low to moderate evidence for clinical recommendation. Conclusion Available evidence reveals NIBS as an effective and safe approach to treat GAD, PTSD and OCD with low recommendation level to clinical application. A great heterogeneity of studies indicates the necessity to develop new randomized clinical trials applying NIBS to treat those and other mental disorders. (AU)

Effects of Transcranial Direct Current Stimulation on Muscle Fatigue in Recreational Runners: Randomized, Sham-Controlled, Triple-Blind, Crossover Study-Protocol Study.

OBJECTIVES: The aim of this study is to evaluate the effects of transcranial direct current stimulation (tDCS) on central and peripheral fatigue in recreational runners. DESIGN: This is a clinical randomized, sham-controlled, triple-blind, crossover study. Twenty adult runners will be randomized on the first day of the intervention to receive active or sham tDCS before fatigue protocol. After 1 wk, the participants will receive the opposite therapy to the one that they received on the first day. The tDCS, 2 mA, will be applied for 20 mins over the motor cortex. The fatigue protocol will be performed after tDCS, in which the participant should perform concentric knee flexion/extension contractions until reaching three contractions at only 50% of maximum voluntary contraction. Central fatigue will be evaluated with the motor evoked potential of the quadriceps muscle; peripheral fatigue with the peak torque (N.m) using an isokinetic dynamometer; the electrical activity of the quadriceps muscle using surface electromyography (Hz); blood lactate level (mmol/L); and the subjective perception of effort (Borg scale). All evaluations will be repeated before and after the interventions. CONCLUSION: This study will evaluate the effect of tDCS on fatigue in runners, possibly determining an application protocol for this population.