Abstract
Background: Age is an important factor that impacts the variability of tDCS effects.Objective/Hypothesis: To compare effects of anodal (a)-tDCS over the left dorsolateral prefrontal cortex (DLPFC), and primary motor cortex (M1) in adolescents, adults, and elderly on heat pain threshold (HPT; primary outcome) and the working memory (WM; secondary outcome). We hypothesized that the effect of tDCS on HPT and WM performance would be the largest in adolescents because their pre-frontal cortex is more prone to neuroplasticity.Methods: We included 30 healthy women within the age ranges of 15–16 (adolescents, n = 10), 30–40 (adults, n = 10), and 60–70 (elderly, n = 10) years. In this crossover single-blinded study, participants received three interventions applied over the DLPF and M1. The active stimulation intensity was two mA for 30 min. From 20 min of stimulation onset, the tDCS session was coupled with an online n-back task. The a-tDCS and sham were applied in a random sequence, with a washout time of a minimum 7 days between each trial. HPT was evaluated before and after stimulation. The WM performance with an n-back task was assessed after the tDCS session.Results: A Generalized Estimating Equation (GEE) model revealed a significant effect of the a-tDCS over the left DLPFC to reduce the HPT in adolescents compared with sham. It increased the pain perception significantly [a large effect size (ES) of 1.09)]. In the adults, a-tDCS over M1 enhanced the HPT significantly (a large ES of 1.25) compared to sham. No significant effect for HPT was found in the elderly. Response time for hits was reduced for a-tDCS over the DLPFC in adolescents, as compared to the other two age groups.Conclusions: These findings suggest that a-tDCS modulates pain perception and WM differentially according to age and target area of stimulation. In adolescents, anodal stimulation over the DLPFC increased the pain perception, while in adults, the stimulation over the M1 increased the pain threshold. Thus, they elucidate the impact of tDCS for different age groups and can help to define what is the appropriate intervention according to age in further clinical trials.Clinical Trial Registration: www.ClinicalTrials.gov, Identifier: NCT04328545.
Highlights
Transcranial direct current stimulation modulates cortical excitability with a low-intensity continuous electric current applied via two or more electrodes placed on the scalp (Nitsche and Paulus, 2000; Nitsche et al, 2008)
The blinding of the participants related to the intervention was successful, and there was no significant difference in the guessing for active stimulation or sham
For a-Transcranial direct current stimulation (tDCS) on the dorsolateral prefrontal cortex (DLPFC), the sleepiness was reported to either elderly (55%), and adults (10%) but not in adolescents (P = 0.014)
Summary
Transcranial direct current stimulation (tDCS) modulates cortical excitability with a low-intensity continuous electric current applied via two or more electrodes placed on the scalp (Nitsche and Paulus, 2000; Nitsche et al, 2008). The a-tDCS over the DLPFC can improve several cognitive domains such as perception, attention, working memory, learning, and decision-making (Teixeira-Santos et al, 2015) This area’s stimulation modulates a core circuit of working memory on the frontoparietal cortical regions (Fregni et al, 2005). These general effects of the tDCS efficacy are not entirely homogeneous (Fertonani and Miniussi, 2017; Mahdavi and Towhidkhah, 2018). They depend on anatomical factors (e.g., gray matter density, cytoarchitecture, baseline activity/excitability state), and, neuroplasticity intrinsic factors, such as genetics, sex, time of day, cognitive involvement, and age (Ridding and Ziemann, 2010). Age is an important factor that impacts the variability of tDCS effects
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
