The effect of the interval-between-sessions on prefrontal transcranial direct current stimulation (tDCS) on cognitive outcomes: a systematic review and meta-analysis

Abstract

Recently, there has been wide interest in the effects of transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) on cognitive functioning. However, many methodological questions remain unanswered. One of them is whether the time interval between active and sham-controlled stimulation sessions, i.e. the Interval Between Sessions (IBS), influences DLPFC tDCS effects on cognitive functioning.Therefore, a systematic review and meta-analysis was performed of experimental studies published in PubMed, Science Direct, and other databases from the first data available to February 2016. Single session shamcontrolled within-subject studies reporting the effects of tDCS of the DLPFC on cognitive functioning in healthy controls and neuropsychiatric patients were included. Cognitive tasks were categorized in tasks assessing memory, attention, and executive functioning. Evaluation of 188 trials showed that anodal vs. sham tDCS significantly decreased response times and increased accuracy, and specifically for the executive functioning tasks, in a sample of healthy participants and neuropsychiatric patients (although a slightly different pattern of improvement was found in analyses for both samples separately). The effects of cathodal vs. sham tDCS (45 trials), on the other hand, were not significant. IBS ranged from less than one hour to up to one week (i.e. cathodal tDCS) or two weeks (i.e. anodal tDCS). This IBS length had no influence on the estimated effect size when performing a meta-regression of IBS on reaction time and accuracy outcomes in all three cognitive categories, both for anodal and cathodal stimulation. Practical recommendations and limitations of the study are further discussed.

One MRI‐compatible tDCS session attenuates ventromedial cortical perfusion when exposed to verbal criticism: The role of perceived criticism

“…Subjects were removed from the scanner, after which the tDCS surface electrodes (25 cm 2 ) were covered in electrode gel and positioned on the scalp based on each participant's structural scan using the Brainsight neuronavigation system (Brainsight™, Rogue Research, Inc., Montreal, Quebec, Canada). To avoid carry-over tDCS effects, based on our recent meta-analysis (Dedoncker, Brunoni, Baeken, & Vanderhasselt, 2016b), the time interval between the two stimulation sessions (active/sham tDCS) was at least 2 days. The cathodal electrode was placed on the right supraorbital area (1 cm above the eyebrows; Figure 1).…”

The influence of endogenous estrogen on transcranial direct current stimulation: A preliminary study

“…While no studies have assessed the impact of estrogen on tDCS induced neuromodulation, two retrospective analyses of TMS data, one cognitive study and a systematic review have examined the impact of gender. Collectively they found that, compared with men, women demonstrated greater changes in motor and visual evoked potential amplitudes, visual phosphine thresholds, and cognition following tDCS, and may be more responsive to right hemisphere stimulation under certain cognitive demands (Chaieb, Antal, & Paulus, ; Dedoncker, Brunoni, Baeken, & Vanderhasselt, ; Kuo, Paulus, & Nitsche, ; Meiron & Lavidor, ). However, all but one of these investigations was retrospective and information regarding menstrual phase, and thus estrogen levels, were not available for analysis.…”

“…Moreover, only the studies by Dedoncker et al. () and Meiron and Lavidor () examined the dorsolateral prefrontal cortex (DLPFC) tDCS, with Chaieb et al. and Kuo et al.…”

“…However, all but one of these investigations was retrospective and information regarding menstrual phase, and thus estrogen levels, were not available for analysis. Moreover, only the studies by Dedoncker et al (2016) and Meiron and Lavidor (2013) examined the dorsolateral prefrontal cortex (DLPFC) tDCS, with Chaieb et al and Kuo et al focusing instead on the visual and motor cortex, respectively. Consideration of regional specificity is important as, due to differences in histological architecture such as neuronal orientation, receptor type and density, and regional connectivity properties, the influence of tDCS is likely to differ between brain regions (Nitsche & Paulus, 2000).…”

Neurocognitive Effects of Transcranial Direct Current Stimulation in Arithmetic Learning and Performance: A Simultaneous tDCS-fMRI Study

“…However, it should be noted that while enhancing effects of anodal tDCS in cognition are consistently reported, the effects of cathodal tDCS are less clear [10,11]. Nevertheless, tDCS has not only become useful for investigating brain function in diverse domains, but is also starting to be used for the treatment of various neuropsychiatric disorders [12].…”