Article Figures & Data
Figures
- Figure 1.
Overview of the experimental procedure. The control group followed the same procedure as the active and sham groups, but without the electrode montage. Stimulation started immediately after tests at T1 were completed. Tests at T2 were administered after 7 min of stimulation. Tests at T3 were administered immediately after the stimulation was completed.
- Figure 2.
Seconds to complete GPD at pretest (1), during stimulation (2), and post-test (3). Error bars denote the SEM.
- Figure 3.
Seconds to complete GPN at pretest (1), during stimulation (2), and post-test (3). Error bars denote the SEM.
- Figure 4.
Seconds to complete TMT at pretest (1), during stimulation (2), and post-test (3). Error bars denote the SEM.
Tables
Sham group Active group Control group p* Total n (female n) 20 (10) 20 (11) 20 (8) 0.64 Right handed (n) 19 19 18 0.77 Age (years) 23.65 (3.12) 24.10 (4.24) 23.80 (3.33) 0.92 BMI (kg/m2) 25.01 (4.10) 24.32 (2.89) 25.80 (4.55) 0.49 Head circumference (cm) 57.30 (2.01) 57.30 (1.47) 57.48 (1.61) 0.94 Sleep time (h) 6.95 (1.06) 6.95 (1.38) 6.78 (1.63) 0.90 Doses of nicotine (n) 0.65 (1.27) 0.60 (.88) 1.5 (2.01) 0.10 Cups of coffee (n) 0.60 (.82) 0.75 (1.29) 0.85 (1.01) 0.77 Awake time (h) 5.25 (2.29) 5.57 (3.42) 4.10 (2.44) 0.22 Impedance (kΩ) NA 5.01 (1.09) NA NA No nicotine doses (n) 14 13 9 NA No coffee (n) 11 12 9 NA Values are reported as the mean (SD), unless otherwise indicated. Frequencies for participants who did not consume nicotine and caffeine 2 h before the experiment are displayed. NA, Not applicable.
*p Value for one-way ANOVA for variable × group interaction.
- Table 2:
Mean values for GPT with dominant and non-dominant hand (GPD / GPN) and TMT with confidence intervals on 1 pre-test, 2 during stimulation and 3 post-test, and T1-T3 Δ scores with 95% confidence intervals
Sham group Active group Control group Mean Mean 95% CI Mean 95% CI Mean 95% CI GPD1 59.79 55.82–63.76 60.43 55.55–65.32 59.41 56.07–62.74 GPD2 55.12 51.69–58.55 55.61 52.20–58.72 55.26 52.38–58.14 GPD3 54.36 51.39–57.34 54.68 51.25–58.11 54.92 52.00–57.84 GPN1 65.00 60.78–69.21 64.62 60.54–68.70 68.67 62.67–74.68 GPN2 61.86 58.60–65.11 61.82 58.15–65.49 64.43 60.79–68.08 GPN3 61.08 57.30–64.85 59.34 55.51–63.18 62.53 58.65–66.41 TMT1 37.84 31.84–43.87 36.09 30.30–41.88 38.45 33.66–43.24 TMT2 25.18 21.33–29.04 27.37 24.89–29.85 25.17 22.69–27.65 TMT3 21.60 19.41–23.79 21.84 19.79–23.88 21.96 19.42–24.51 GPD Δ 5.42 3.11–7.73 5.76 2.31–9.20 4.49 2.63–6.35 GPN Δ 3.92 0.66–7.18 5.28 2.95–7.61 6.14 2.18–10.11 TMT Δ 16.24 11.34–21.14 14.26 8.90–19.61 16.49 11.65–21.33 B t β p Partial correlation Regression 1 Included variables BMI 0.77 2.26 0.29 0.03* Excluded variables Sham 0.04 0.30 0.76 0.04 Control 0.02 0.14 0.89 0.02 Gender −0.15 −1.23 0.22 −0.16 Regression 2 Included variables Gender 3.28 2.01 0.27 0.52 Impedance −1.77 −2.46 −0.32 0.02* Caffeine intake 2.11 0.75 0.37 0.01** - Table 4:
Frequency of sessions after which specific adverse effect occurred, and the mean intensity for specific adverse effects across all sessions defined as 0 = none, 1 = mild, 2 = moderate, 3 = severe.
Frequency by sessions Mean intensity (SD) Sham group (n =20) Active group (n = 20) Sham group Active group Sham group p* Headache 6 2 0.60 (.94) 0.20 (.62) 0.120 Neck pain 2 0 0.20 (.62) 0 0.154 Scalp pain 3 3 0.40 (.99) 0.40 (1.05) 1 Tingling 8 8 0.80 (1.01) 0.80 (1.01) 1 Itching 5 6 0.55 (1.00) 0.75 (1.25) 0.580 Burning sensation 6 13 0.7 (1.13) 1.45 (1.19) 0.048** Skin redness 11 17 1.25 (1.25) 1.95 (.94) 0.053 Sleepiness 9 6 1.00 (1.21) 0.85 (1.42) 0.722 Trouble concentrating 1 3 0.10 (.45) 0.40 (.99) 0.226 Acute mood change 0 0 0 0 1 Others 1 1 .10 (.45) .30 (.73) 0.304 *p-value for independent samples t-test for group differences in adverse effect intensity.
**p < .05.
Data structure Type of test Power (%) a GPD Normally distributed One-way ANOVA 6 b GPN Normally distributed One-way ANOVA 20 c TMT Normally distributed One-way ANOVA 8 d GPD RM time Normally distributed RM ANOVA 100 e GPD*group Normally distributed RM ANOVA 9 f GPN RM time Normally distributed RM ANOVA 100 g GPN*group Normally distributed RM ANOVA 13 h TMT RM time Normally distributed RM ANOVA 100 i TMT*group Normally distributed RM ANOVA 9 j Δ GPD Normally distributed One-way ANOVA 9 k Δ GPN Normally distributed One-way ANOVA 13 l Δ TMT Normally distributed One-way ANOVA 15 m Δ GPD (sham and control) Normally distributed One-way ANOVA 81 n Δ GPN (sham and control) Normally distributed One-way ANOVA 99 o Δ TMT (sham and control) Normally distributed One-way ANOVA 12 p Corr all Non-normally distributed Partial Pearson correlation, two-tailed 65 q Corr active Non-normally distributed Partial Pearson correlation, two-tailed 25 r Regression all Non-normally distributed* Linear multiple regression 97 s Regression active Non-normally distributed* Linear multiple regression 41 Lines refer to the alphabetical value provided in the Results section. Post hoc power calculations were performed on the sampled data in G*Power for Windows. For one-way and RM ANOVA, the n and SDs from the data with desired alpha level of 0.05 were used. For the correlation analysis, a hypothetical regression value of 0.03 against a zero correlation were used. For regression analysis, the observed R2 values were used. Deviations from normal distribution in the sample containing all participants were significantly non-normal: head circumference, D(60) = 0.15, p < 0.01; age, D(60) = 0.22, p < 0.01; doses of nicotine in last 2 h before undergoing stimulation, D(60) = 0.33, p < 0.01; doses of caffeine in last 2 h before undergoing stimulation, D(60) = 0.29, p < 0.01; hours awake, D(60) = . , p = 0.02; and hours of sleep, D(60) = 0.15, p < 0.01. Deviations from normal distribution in the sample containing participants from the active group were significantly non-normal: age, D(20) = 0.21, p = 0.02; doses of nicotine in last 2 h before undergoing stimulation, D(20) = 0.40, p < 0.01; doses of caffeine, D(20) = 0.32, p < 0.10; and hours of sleep, D(20) = 0.21, p = 0.02.
*The assumptions for regression regarding homoscedasticity, independent errors and normally distributed errors were met.
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