Traveling-wave Transcranial Electric Stimulation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Traveling-wave Transcranial Electric Stimulation (NCT05399381), a randomized na study. The primary outcome is Working Memory Accuracy (N-back Task).

2. Clinical Question

The main statistical question is whether the observed condition means are distinguishable with useful precision, given the limited number of participants represented in the posted summaries and the repeated-measures crossover design. The record includes unadjusted recalculated comparisons of each listed condition with the reference condition, but no sponsor-reported outcome analyses. These distinctions matter: a condition mean describes observed task performance, whereas a comparison estimates the contrast between two conditions. Neither alone explains how the estimates were obtained under the crossover design.

The registry record also lists changes in reaction time and theta-band frontoparietal EEG phase connectivity as secondary outcomes. Those measurements provide additional descriptions of task performance and EEG response, but they are not substitutes for the primary accuracy measure. The results should therefore be read as exploratory evidence about patterns across these outcomes, rather than as a single definitive test of the intervention.

3. Trial Design

The registry identifies NCT05399381 as a completed study titled “Traveling-wave Transcranial Electric Stimulation.” The official title is “Precision Transcranial Electric Stimulation for the Therapy of Cognitive Impairment.” The listed condition is working memory, and the study intervention is transcranial alternating current stimulation (tACS), classified as a device. The registry lists phase as NA.

The study is described as randomized, triple-blind, and crossover. The condition descriptions characterize it as a randomized, triple-blind, sham-controlled, within-subject crossover study. They state that each participant completed two study sessions separated by a minimum 48-hour washout period, and that participants received all conditions with randomized crossover sequence differing across participants. The registry record does not fully explain how the four active stimulation conditions were scheduled across the two sessions, or how the sham condition relates to the outcome groups posted in the results.

Enrollment is listed as 34. The posted primary and secondary outcome summaries each report 29 participants in each condition. The reason that the summary count differs from enrollment is not reported in the registry record; the figures alone do not establish whether this reflects missing observations, exclusions, or another analysis-population decision. The record lists a study start of 2022-09-05, primary completion of 2025-02-01, and status as completed.

The primary outcome timeframe is during each stimulation block, described as approximately 20 minutes per block, in two study sessions on separate days with a minimum 48-hour washout. The record lists three outcome measures, with two secondary outcomes. It does not report sponsor-conducted statistical analyses for the posted results. The original sample-size rationale, planned model for the crossover data, randomization sequence details, and original analysis plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: All participants were assigned to a single randomized within-subject crossover arm. Each participant completed two study sessions separated by a washout period, receiving two active stimulation conditions per session. Across both sessions, every participant received all four active stimulation conditions exactly once. Counts shown for individual conditions are session-specific and do not represent separate treatment arms.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All participants were enrolled in a randomized, within-subject crossover design and received all stimulation conditions across two sessions

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Baseline characteristics are reported for the 29 participants who completed both study sessions and were included in the final within-subject analysis. The study design was Randomized, triple-blind, sham-controlled, within-subject crossover study. Each participant received all four active stimulation conditions and sham stimulation across two study sessions. The order of the four active stimulation conditions differed across participants according to the randomized crossover sequence.

6. Primary Endpoint

The registry lists the primary outcome as Working Memory Accuracy (N-back Task), measured over During each stimulation block (approximately 20 minutes per block) in two study sessions conducted on separate days and separated by a minimum 48-hour washout period..

The primary endpoint is Working Memory Accuracy (N-back Task). It measures the proportion of correct responses during performance of the N-back working-memory task within each stimulation block. The posted outcome summaries give a mean and standard deviation for each stimulation condition, with the measure expressed as a proportion.

Accuracy is a direct measure of task performance: it describes how often responses were correct, rather than the speed of responding or a brain signal. That makes it useful for addressing the study’s stated question about working-memory performance. Reaction time and EEG phase connectivity offer different kinds of information and are listed as secondary outcomes.

The registry describes the primary measure as absolute task performance during active or sham stimulation in a within-subject crossover design. However, the posted primary outcome groups are named for four stimulation conditions, and no separate sham outcome group is listed in the results. The record does not clarify this difference in reporting. The posted condition means therefore describe performance in the listed groups; they should not be treated as a direct comparison with a separately reported sham condition.

A mean is a compact summary of participants’ observed scores, while the standard deviation describes how spread out those scores are around the mean. Neither summary shows how individual participants changed between conditions. Because this is a crossover study, the within-participant condition differences are particularly relevant. The registry record does not report participant-level data or a sponsor analysis that models those repeated measurements.

7. Results Posted in the Registry

• Frontoparietal Fast Theta Stimulation: mean 0.79 versus 0.77 on control; difference 0.02 (95% CI -0.04 to 0.08), standardized effect d = 0.17; z-test p = 0.527.
• Parietofrontal Slow Theta Stimulation: mean 0.82 versus 0.77 on control; difference 0.05 (95% CI -0.00 to 0.10), standardized effect d = 0.48; z-test p = 0.070.
• Parietofrontal Fast Theta Stimulation: mean 0.78 versus 0.77 on control; difference 0.01 (95% CI -0.04 to 0.06), standardized effect d = 0.10; z-test p = 0.717.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Changes in Reaction Time

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Frontoparietal Fast Theta Stimulation: mean 710.71 versus 626.26 on control; difference 84.45 (95% CI -21.03 to 189.93), standardized effect d = 0.41; z-test p = 0.117.
  • Parietofrontal Slow Theta Stimulation: mean 694.57 versus 626.26 on control; difference 68.31 (95% CI -36.40 to 173.02), standardized effect d = 0.34; z-test p = 0.201.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Frontoparietal Fast Theta Stimulation and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Parietofrontal Slow Theta Stimulation and the control. The interval gives the range of effects that remain compatible with the data.

Theta-band Frontoparietal EEG Phase Connectivity (dwPLI)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Frontoparietal Fast Theta Stimulation: mean 0.02 versus -0.01 on control; difference 0.03 (95% CI 0.01 to 0.05), standardized effect d = 0.70; z-test p = 0.008.
  • Parietofrontal Slow Theta Stimulation: mean 0.06 versus -0.01 on control; difference 0.07 (95% CI 0.04 to 0.10), standardized effect d = 1.19; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Frontoparietal Fast Theta Stimulation than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Parietofrontal Slow Theta Stimulation than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes broaden the description beyond N-back accuracy. Reaction time concerns how quickly participants responded, while theta-band frontoparietal EEG phase connectivity concerns an EEG measure recorded around the stimulation blocks. Together, these outcomes describe different aspects of task performance and brain-signal measurements; they should not be treated as interchangeable indicators of a single effect.

Across the posted secondary results, the recalculated reaction-time comparisons are uncertain, with confidence intervals that include zero. The EEG connectivity comparisons against the reference condition show positive estimated contrasts, and the listed unadjusted p-values are more suggestive for those measures than for the primary accuracy comparisons. These broad patterns do not change the primary result: the accuracy comparisons remain imprecise, and the registry does not report a sponsor analysis tying the secondary outcomes to a confirmatory conclusion.

Secondary findings generally carry less evidential weight when many outcomes or comparisons are examined without a reported multiplicity plan. A nominally small unadjusted p-value can arise by chance among multiple tests, and selective emphasis on the most notable finding can overstate evidence. The registry record lists two secondary outcomes and contains no reported analyses or adjustment strategy. It is therefore not possible to determine whether the observed secondary patterns were prespecified, adjusted, or interpreted under a hierarchy of outcomes.

The secondary measures may be useful for generating questions about how stimulation conditions relate to speed and EEG connectivity. However, the record does not report a unified model linking those measures to accuracy, nor does it report thresholds for meaningful changes. Without that context, secondary results should be considered exploratory descriptions rather than independent confirmation of the primary outcome.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Changes in Reaction Time
• Theta-band Frontoparietal EEG Phase Connectivity (dwPLI)

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is a continuous measure summarized by its mean and standard deviation. A mean describes the average observed accuracy in a condition. A standard deviation describes variation among scores around that mean; it is not the uncertainty in the mean and is not a confidence interval. The posted summaries give 29 participants in each of the four conditions.

What does a mean difference describe?

A mean difference compares the average value in one condition with the average in the reference condition. In the primary comparisons, Frontoparietal Slow Theta Stimulation serves as the reference. A positive estimate means that the other condition’s posted mean is higher than the reference mean in the direction used for the calculation. This is a descriptive direction, not evidence by itself that the difference is real, important, or caused by the intervention.

The listed primary differences and p-values are recalculated unadjusted comparisons from posted summary statistics. They are not analyses reported by the sponsor. The registry record lists no reported primary analyses, and it does not identify a statistical model for the crossover measurements. That distinction is important because the same participants are described as receiving each condition. A paired analysis uses information about how each person’s results change across conditions. Simple summaries of separate condition means do not reveal the correlation between those repeated measurements.

Why does the crossover design matter?

In general, crossover trials can account for stable differences between participants because each participant receives multiple conditions. Appropriate analysis may also need to consider period, sequence, and possible carryover effects. The registry record describes randomized sequences and a minimum 48-hour washout, but does not report the sponsor’s analysis of period or sequence, whether carryover was assessed, or how repeated observations were modeled. The recalculated comparisons should not be mistaken for a full crossover analysis.

What do the confidence intervals and p-values contribute?

A confidence interval gives a range of values compatible with the estimate under the calculation and its assumptions. A wider interval indicates less precision; an interval containing zero does not establish that the true difference is exactly zero. The primary intervals include zero. The associated p-values describe how unusual results at least as far from zero would be under a null model of no difference, if that model and the calculation assumptions hold. They do not give the probability that the null hypothesis is true, nor do they measure clinical importance.

All posted p-values for the primary comparisons are unadjusted. When several comparisons are considered, the chance of at least one apparently notable result can increase if each is assessed separately. A prespecified adjustment or hierarchy can address that issue, but the registry record does not report whether such a plan existed. No multiplicity-adjusted interpretation can be reconstructed from the posted information.

What does standardization add?

The standardized effect-size values express each mean contrast relative to a pooled standard deviation. Standardization can help describe the size of a contrast on a scale that is less dependent on the outcome’s units. It does not resolve uncertainty, correct a design mismatch, or establish whether a difference matters to participants. The record does not report a threshold for a meaningful effect.

Why can spread affect inference?

In general, greater participant-to-participant variation makes a mean harder to estimate precisely when the sample size is unchanged. The standard deviations describe variation in observed accuracy, while the confidence intervals also depend on the number of participants and the calculation’s assumptions. For repeated measurements, the correlation between condition scores can change the precision of a paired contrast. That correlation is not available in the registry record, so the recalculated intervals do not use a reported within-participant covariance.

What does an unadjusted recalculation mean?

A recalculation from posted means and standard deviations is a transparent descriptive check, but it cannot replace a trial’s prespecified model. The trial’s original statistical plan, sample-size justification, interim analyses, and handling of missing data are not reported in the registry record. The calculations should therefore be read as approximate, unadjusted summaries of the posted information, not as a definitive test of the trial’s primary hypothesis.

11. Confidence Intervals and Precision

The precision of an estimate is reflected in the range of values that remain compatible with it, as represented by its confidence interval. The primary intervals are relatively broad compared with their point estimates and include zero for all three comparisons. This means the posted recalculated results do not tightly locate the condition differences. For each comparison, values on both sides of zero remain within the interval, although the span differs by contrast.

For Frontoparietal Fast Theta Stimulation versus the reference, the interval runs from -0.042 to 0.082 around a mean difference of 0.02. For Parietofrontal Slow Theta Stimulation, it runs from -0.004 to 0.104 around 0.05. For Parietofrontal Fast Theta Stimulation, it runs from -0.044 to 0.064 around 0.01. These ranges are more informative than treating the point estimates as exact. In particular, the parietofrontal slow estimate is compatible with a near-zero contrast as well as a larger positive contrast.

Confidence intervals are conditional on the method and assumptions used to construct them. Here, the comparisons are recalculated from posted summary statistics, and the registry record does not report a sponsor analysis of the crossover observations. The participant-level pairing information is not reported, so the intervals do not document the precision of a sponsor-reported paired model. The posted sample summaries also do not explain why each condition has 29 participants when enrollment is 34.

In general, an interval should not be read as a range that contains the true value with certainty, nor does inclusion of zero prove the absence of a difference. Instead, it conveys sampling uncertainty under the calculation. For this study, the intervals indicate that the posted data do not give a highly precise estimate of the contrasts. The record does not provide a clinical or functional threshold against which to judge whether any part of these ranges would be important.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size illustrations express the number of participants per arm for 80% power and the number of participants per arm for 90% power. These are participant counts, not total event counts. They are planning illustrations based on the observed contrast and do not describe the number enrolled in this trial or the number needed for its original design.

The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning row uses the stated fraction of the observed effect as the effect to detect. The illustrations show the number per arm for detecting 100% of the observed effect, 75% of the observed effect, or 50% of the observed effect. The original trial’s sample-size assumptions and justification are not reported in the registry record.

In plain language, 80% power means that, under the planning assumptions and if the target effect were present, the design would have an 80% chance of rejecting the null hypothesis. The 90% power column uses the corresponding higher target probability. These are properties of hypothetical future designs, not guarantees about a result.

Smaller effects are harder to distinguish from random variation, so the planning illustrations require more participants per arm as the target effect becomes a smaller fraction of the observed effect. This relationship is a general feature of statistical planning; it does not mean the smaller effect is unimportant.

These figures are not observed power. Observed power is not a useful substitute for the confidence intervals and estimates after data have been collected. The planning values are illustrations conditional on the stated assumptions and on effects derived from the posted results; they are not the trial’s original design plan.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.020; pooled standard deviation σ = 0.120.
2. n = 2 × (1.96 + 0.842)² × 0.120² / 0.020² = 569.0, rounded up to 570 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.02                      # observed difference in means
sigma <- 0.120415945787923                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(5399381)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 570 (80% power), 762 (90% power)
 75% of observed effect: n per arm = 1,012 (80% power), 1,355 (90% power)
 50% of observed effect: n per arm = 2,277 (80% power), 3,048 (90% power)
power.t.test: 570 
Simulated power at n = 570 per arm: 0.800 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The posted primary results include three comparisons with a reference condition, and the record also includes secondary outcomes with their own comparisons. When multiple hypotheses are tested, interpreting each unadjusted p-value as if it were the only test can make chance findings more likely. Statistical plans commonly address this with a prespecified testing hierarchy or an adjustment for multiple comparisons. Whether the study planned either approach is not reported in the registry record.

The recalculated p-values are explicitly unadjusted. There are no sponsor-reported analyses in the record, and no multiplicity-adjusted results are posted. Consequently, the p-values should not be read as confirmatory evidence across the full set of outcomes. In particular, a secondary result with a small unadjusted p-value does not automatically outweigh the primary outcome or resolve its uncertainty.

The registry lists enrollment of 34, while the posted outcome summaries show 29 participants in each condition. The reason for this difference, the number of participants with complete data, and the handling of missing observations are not reported in the registry record. It is not possible to determine from the summaries whether data were excluded, unavailable, or handled using another method.

The analysis population is also not fully described. The primary outcome description refers to all participants enrolled in a within-subject design, but the posted outcome groups report 29 participants per condition. The record does not identify an intention-to-treat population, a per-protocol population, or another defined analysis set. It does not report how participants with incomplete crossover sequences were treated.

Likewise, interim analyses, stopping rules, the original sample-size justification, and the sponsor’s statistical analysis plan are not reported in the registry record. These omissions limit assessment of whether the posted comparisons match the intended primary analysis. They do not establish that appropriate procedures were absent; they mean that the record does not document them.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The safety summaries list 29 participants at risk in each of the four stimulation-condition groups. Each group reports zero serious adverse events, zero other adverse events, and zero deaths. No serious adverse-event terms are listed.

These figures describe the adverse-event information posted for the groups. They do not show events beyond the registry’s specified reporting, and they do not establish that no adverse events of any kind occurred outside the posted categories or observation period. The record does not provide additional detail about event collection, attribution, severity definitions, or the duration of safety follow-up.

Because the study is described as a within-subject crossover, the same participants may contribute to more than one condition group. The group counts should therefore not be treated as independent sets of people or added together to infer a total number of distinct participants. The posted data are a descriptive safety record, not a comparative safety analysis.

16. What the Result Does, and Does Not, Mean

The posted results support a limited statistical conclusion: average N-back accuracy was similar across the four listed conditions, and the recalculated condition contrasts are imprecise. The confidence intervals include zero, and the registry record does not contain a sponsor-reported analysis of the primary outcome. This leaves uncertainty about the size and direction of any condition differences.

The results do not establish that stimulation improved or worsened working-memory performance. The study record describes randomized, triple-blind crossover procedures, but the recalculated comparisons do not account for reported participant-level pairing because those data and a crossover model are not posted. A causal interpretation requires more than differences among summary means; it depends on the design, analysis, missing-data handling, and prespecified comparisons.

The results also do not show that the conditions are equivalent. An interval that includes zero is not proof that the true difference is zero. Demonstrating equivalence would generally require a defined margin for a difference considered unimportant and a corresponding analysis; no such margin or analysis is reported in the registry record.

The secondary outcomes add descriptive information about reaction time and EEG connectivity, but they do not repair the uncertainty in the primary accuracy comparisons. Their interpretation is limited by unadjusted comparisons and the absence of a reported multiplicity plan. No threshold for a meaningful change in the secondary measures is reported.

The posted safety summaries report no serious adverse events, other adverse events, or deaths in the listed groups. Those summaries are limited to what the registry reports and cannot support a broader claim about safety outside the recorded groups or follow-up.

In general, a trial result is best understood through its estimate, precision, design, and analysis plan together. In this record, key analysis details are unavailable. The appropriate reading is therefore descriptive and cautious: the available summaries do not resolve whether the stimulation conditions produce meaningful differences in working-memory accuracy.

17. Why This Trial Matters Statistically

This trial raises an important statistical issue: a crossover design produces repeated measurements within the same participants, so analysis should reflect the paired structure. Comparing condition means as if they were independent can fail to use information about within-person changes and can misrepresent uncertainty. The registry describes a within-subject design, but does not report the sponsor’s model or the participant-level covariance needed to assess that analysis.

The trial also illustrates why a point estimate, a p-value, and a confidence interval answer different questions. A mean difference gives a direction and scale; a p-value summarizes compatibility with a null model under assumptions; and a confidence interval communicates uncertainty over a range of plausible contrasts. The primary summaries show why these should be considered together rather than reducing interpretation to one threshold.

Another statistical concern is the distinction between primary and secondary outcomes. The study posts accuracy, reaction time, and EEG connectivity, with multiple condition comparisons. Without a reported hierarchy or multiplicity plan, isolated unadjusted findings should be treated cautiously. This is especially relevant when secondary outcomes appear more suggestive than the primary endpoint.

The planning illustrations further emphasize that sample-size requirements depend on the effect a future study aims to detect. Smaller target effects require more participants under the stated assumptions. Such planning values can help frame future research questions, but they are not evidence that the current study was adequately powered or that any observed effect is established.

Overall, the registry record is a useful case for distinguishing descriptive summaries from confirmatory analysis. The posted numbers invite careful attention to repeated-measures methods, precision, multiplicity, and transparency about analysis populations.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations are specific to the available record. First, the posted primary comparisons are recalculations from condition-level summary statistics, not sponsor-reported analyses. The record describes a crossover design but does not provide participant-level paired data or a model accounting for within-person association. This prevents a direct assessment of a crossover-aware estimate and its uncertainty.

Second, there is a reporting mismatch that cannot be resolved from the record: the descriptions characterize the study as sham-controlled, but the posted outcomes list four stimulation conditions without a separate sham outcome group. The condition descriptions also refer to two sessions and receipt of all conditions, while the details of how the conditions were arranged are incomplete. The full protocol details are not reported in the registry record.

Third, enrollment is 34, while each posted outcome group reports 29 participants. The reasons for this difference and the handling of missing or incomplete observations are not reported. The analysis population and rules for including participants are not specified in the posted results.

Fourth, the registry does not report the original sample-size justification, the statistical analysis plan, interim analyses, multiplicity procedures, or a prespecified threshold for meaningful change. It also does not report whether period, sequence, or carryover effects were modeled. These gaps limit evaluation of how closely the recalculated results reflect the trial’s intended analysis.

Finally, all condition-level summaries conceal individual response patterns. The available means and standard deviations do not show whether participants responded consistently across conditions or whether a small number of observations influenced the averages. These limitations concern what can be learned from the registry record; they do not establish that the underlying study did not collect or analyze additional information.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Traveling-wave Transcranial Electric Stimulation — NCT05399381.
• Registry record last updated 2026-08-20; status last verified 2026-07.
• Results first posted 2026-08-20.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

22. Record Summary

NCT05399381 is a completed randomized, triple-blind crossover study of transcranial alternating current stimulation and working-memory performance. The registry lists enrollment of 34 and a primary outcome of N-back task accuracy. Posted accuracy summaries include 29 participants per stimulation condition.

The recalculated unadjusted primary comparisons have confidence intervals that include zero. The registry record does not report sponsor-conducted outcome analyses, a crossover analysis model, multiplicity procedures, or missing-data handling. Secondary reaction-time and EEG connectivity outcomes add exploratory context, while the posted safety summaries list zero serious adverse events, other adverse events, and deaths in each condition group.

The results are best read as condition-level descriptive summaries with substantial uncertainty, not as a definitive estimate of a causal effect.