Promoting Adaptive Neuroplasticity in Mild Cognitive Impairment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Promoting Adaptive Neuroplasticity in Mild Cognitive Impairment (NCT02155946), a randomized na study. The primary outcome is Face-name Memory Test Performance.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, double-blind, parallel study, marked completed. The study title is “Promoting Adaptive Neuroplasticity in Mild Cognitive Impairment.” It lists the VA Office of Research and Development as sponsor and records enrollment of 107. The listed study start is 2014-12-01 and primary completion is 2021-02-28. Phase is recorded as NA.

The four described groups combine stimulation condition and memory activity: active tDCS or sham tDCS, each paired with mnemonic strategy training or autobiographical memory recall. The registry lists two device interventions, both named as a Soterix Medical Inc. tDCS unit. The numerical results identify four arms as Arm 1 through Arm 4. The record does not explicitly map those numbered arm labels to the four named combinations, so that mapping should not be inferred from the arm numbers.

Face-name memory performance was assessed as change from baseline to post-session 5, identified as day 5 after baseline. The registry describes laboratory-based and real-world memory testing, as well as brain imaging, as part of the study’s broader assessment. The listed secondary outcomes are Prose Memory, MMQ - Strategy Subscale, and Spatial Navigation. The registry records 8 outcome measures and 0 analyses.

Randomization supports a comparison design, while masking is intended to reduce the influence of expectations on assessment or treatment experience. Those design labels do not by themselves explain whether allocation was concealed, who was masked, or how masking was maintained. Such procedural details are not reported in the registry record. The record also does not report the planned randomization ratio or the intended sample size by group.

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.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Patient-level factors of age, sex, race, RBANS Delayed Memory Index, MoCA, Emory version of the Wisconsin Card Sorting Test were included as covariates.

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.

6. Primary Endpoint

The registry lists the primary outcome as Face-name Memory Test Performance, measured over change from baseline to post session 5 (day 5 after baseline).

The primary endpoint is change in face-name memory test performance from baseline to post-session 5, described as day 5 after baseline. Performance is the raw number of face-name pairs correctly recalled or recognized, with a maximum score of 15 points. Higher scores indicate better performance at a given time point. For the change measure, a positive value indicates improvement from baseline, while a negative value indicates decline.

A face-name task measures a specific aspect of memory: learning or retrieving an association between a person’s face and name. It is used as a laboratory-based measure of memory performance. A task with a defined scoring range can make the outcome interpretable as a change in correctly recalled or recognized pairs. The registry does not report evidence establishing how closely change on this task corresponds to changes in everyday memory or functioning.

The primary outcome is continuous, and the posted arm values are means with 95% confidence intervals. The endpoint description says patient-level factors including age, sex, race, RBANS Delayed Memory Index, MoCA, and the Emory version of the Wisconsin Card Sorting Test were included as covariates. The record does not give the fitted model specification or explain how the covariates were incorporated. Data coding errors were identified, and the registry states that accurate values were reported 2/6/2023.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is continuous: it records a numerical change in face-name pairs correctly recalled or recognized. The registry presents a mean for each arm and a 95% confidence interval. The endpoint is defined as change from baseline to post-session 5, with positive values indicating improvement and negative values indicating decline. These details define what the estimates summarize, but do not by themselves show the comparative effect of active versus sham stimulation.

What does a mean change describe?

A mean is a measure of the central location of a set of numerical observations. Here, the reported mean change summarizes the observed change in the endpoint for the participants represented in each arm’s result. It does not imply that every participant changed by that amount. Individual changes can vary around the mean, and the registry does not report the distribution of individual changes or a measure of their variability.

The outcome’s maximum score is 15 points. A mean change is expressed in the same underlying score units, namely face-name pairs correctly recalled or recognized. The description says positive differences indicate improvement and negative differences indicate decline. An estimate near zero therefore describes little average change in this score, but it does not show that each participant remained unchanged.

How should a confidence interval be read?

A confidence interval describes uncertainty in an estimate under a statistical procedure and its assumptions. In repeated use of that procedure, a 95% confidence interval is designed to cover the target parameter in 95% of repetitions. It should not be read as a probability statement about the particular interval after it has been calculated. It also does not describe where 95% of participant outcomes fall.

The registry’s intervals accompany arm-specific mean changes. Whether an interval includes zero can help describe the uncertainty about that arm’s mean change relative to no average change. It does not answer whether two arms differ. To assess a difference between arms, an analysis must estimate that difference and its uncertainty, or report a suitable test. Such a two-arm comparison is not reported as estimable for this endpoint in the registry record.

Why are arm estimates not the same as a treatment contrast?

A treatment contrast compares outcomes between groups using a defined comparison, such as active versus sham stimulation under a specified training condition. Separate means do not provide the uncertainty for that contrast. Even when one arm’s mean differs numerically from another’s, the contrast needs its own estimate and uncertainty; the uncertainty of each arm’s mean cannot substitute for it. The registry marks the two-arm comparison as unavailable or not estimable for this continuous endpoint. Thus, the arm-specific results should not be converted into an unreported treatment effect.

The endpoint description states that age, sex, race, RBANS Delayed Memory Index, MoCA, and the Emory version of the Wisconsin Card Sorting Test were included as covariates. In general, covariate adjustment incorporates selected participant characteristics into a model. Depending on the model and design, adjustment can account for associations between those characteristics and the outcome. The registry does not report the model formula, coding choices, missing-covariate handling, or whether the posted means and intervals are adjusted estimates. Those details are not reported in the registry record, so more specific claims about adjustment are not warranted.

What do the planning illustrations mean?

Sample-size calculations are planning tools. The registry’s stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is defined as a stated fraction of the observed effect. These assumptions describe a hypothetical planning exercise, not the trial’s own design justification. The sample-size justification for the trial is not reported in the registry record.

Such planning illustrations depend on the assumed effect and analysis conditions. They do not measure the probability that the completed study detected an effect, and they are not observed power. The registry’s description says non-time-to-event illustrations are expressed as participants per arm. No particular planning result should be interpreted as the number enrolled or analyzed in an arm. The assumptions and the arm-level outcome counts answer different questions.

More generally, statistical tests and intervals depend on assumptions about the data and model. For continuous outcomes, relevant considerations can include the distribution of errors, the adequacy of the model, and the influence of unusual observations. If a model assumes constant variance but the data are more variable in some groups or regions than others, uncertainty estimates may be poorly calibrated. This is a general statistical consideration; the registry does not report diagnostic checks or enough model detail to determine whether it arose in this study.

The record also does not report interim analyses, a prespecified statistical analysis plan, or how multiplicity was handled. These omissions do not establish that those procedures were absent. They mean that the registry record does not describe them, limiting assessment of how the posted endpoint and analyses relate to the study’s full analytic plan.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies Face-name Memory Test Performance as the primary outcome and lists Prose Memory, MMQ - Strategy Subscale, and Spatial Navigation as secondary outcomes. It records 8 outcome measures and 0 analyses. The listed secondary outcomes indicate that the study assessed more than one outcome, but the registry does not describe a multiplicity strategy, such as an adjustment to account for testing multiple outcomes or comparisons. That procedure is not reported in the registry record. The count of analyses recorded in the registry does not establish whether analyses were or were not conducted outside that listing.

Missing-data handling is also not reported in the registry record. The arm-level endpoint counts are 29, 23, 29, and 24, while overall enrollment is recorded as 107. These entries do not explain why the counts differ, whether all enrolled participants had baseline and follow-up data, or how any unavailable measurements were handled. No imputation method, complete-case rule, or sensitivity analysis is described.

The record does not define the analysis population—for example, whether the reported estimates use all randomized participants, participants with observed endpoint measurements, or another set. It also does not report participant flow by reason for exclusion or withdrawal. The listed covariates are described as included, but the record does not state how missing values in those covariates were addressed.

These reporting gaps matter because conclusions can depend on which observations are analyzed and how incomplete outcomes are treated. They do not show that the analysis was inappropriate; they limit what can be evaluated from the registry record alone.

11. 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 5% reporting threshold.

The registry reports serious adverse events, other adverse events, and deaths by arm. For Arm 1, the record lists 0 serious adverse events among 29 at risk, 0 other adverse events among 29 at risk, and 0 deaths. For Arm 2, it lists 0 serious adverse events among 23 at risk, 0 other adverse events among 23 at risk, and 0 deaths. For Arm 3, it lists 0 serious adverse events among 29 at risk, 0 other adverse events among 29 at risk, and 0 deaths. For Arm 4, it lists 0 serious adverse events among 24 at risk, 0 other adverse events among 24 at risk, and 0 deaths.

These entries mean that no affected participants or deaths are recorded in those categories for the listed groups. They do not establish that no symptoms or other events occurred, and they do not show that risk was absent. The record does not list serious adverse event terms. The timeframe and detailed event definitions are not reported in the registry record. With zero events recorded in the listed categories, comparisons of safety between arms are not informative about relative risk from these figures alone.

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

The posted results answer a limited descriptive question: what mean change in face-name memory performance was recorded in each arm from baseline to post-session 5? The means are negative for all four arms, with Arm 2 near zero, and their confidence intervals communicate uncertainty around those arm-specific estimates. This is evidence about the measured task at the stated assessment time, not a complete account of memory, daily function, or longer-term outcomes.

The results do not establish whether active tDCS improved performance relative to sham tDCS. The registry does not report an estimable two-arm comparison for the continuous primary endpoint. It would therefore be inappropriate to interpret differences between the four displayed means as a confirmed treatment effect or to attribute changes to stimulation rather than the accompanying training, time, or other factors.

The outcome description identifies positive change as improvement and negative change as decline. That scoring direction helps interpret the signs, but a mean change does not describe every participant’s experience. The record does not report individual-level outcome distributions, a clinically meaningful threshold for change, or evidence linking a particular score difference to everyday functioning. It also does not provide results for all the secondary outcomes in the listed secondary-outcome names.

The study’s description proposes that stimulation might enhance the ability to benefit from memory rehabilitation, and identifies laboratory and real-world memory testing and brain imaging as broader areas of assessment. Those aims are not themselves findings. The arm-specific primary outcome values do not show whether the proposed mechanism occurred, whether results generalized to daily life, or whether effects persisted beyond the stated endpoint time.

The registry marks the study completed and records data coding errors that were identified, with accurate values reported 2/6/2023. The reason for those coding errors, their scope, and any consequences for other outcomes are not described. The reported values should be interpreted as the corrected figures identified by the record, while recognizing that the available statistical description does not permit a full audit of the analysis.

13. Why This Trial Matters Statistically

This study is statistically notable for combining a randomized design with four combinations of stimulation condition and memory activity, while reporting a continuous memory outcome. That structure raises a distinction between arm-specific change and the comparative question of interest. Means within groups describe their own outcomes; they do not replace a direct estimate comparing active and sham stimulation.

The primary measure has an explicit direction: positive change means improvement and negative change means decline. Its definition also identifies a fixed assessment point, post-session 5, day 5 after baseline. Clear outcome direction and timing are important because they let readers understand what a numerical change represents. The maximum score of 15 points gives the endpoint a bounded scale, although the registry does not report a threshold for a meaningful change.

The record notes that patient-level factors were included as covariates. This matters to interpretation because the estimate may depend on an adjusted analysis, but the exact model and status of the reported means as adjusted or unadjusted estimates are not specified. Transparent reporting of the model, analysis population, and missing-data approach would help readers assess how the estimates were obtained.

The unavailable two-arm comparison is a central limitation for the causal question. Even in a randomized study, the arm-specific estimates alone do not quantify the active-versus-sham contrast. The registry’s sample-size assumptions also describe planning illustrations rather than the trial’s design rationale or observed power. Keeping those distinctions clear avoids overstating what the posted endpoint results establish.

Finally, the record reports zero affected participants in the listed adverse-event categories, while not supplying event definitions or timing details. Those figures are informative as registry entries, but their scope should not be extended beyond what was recorded. Together, the outcome results and reporting gaps illustrate why statistical interpretation depends on the estimand, comparator, uncertainty, and analysis details—not only on the direction of group means.

14. 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.

The principal limitation for interpreting efficacy is that the registry does not report an estimable two-arm comparison for the primary continuous endpoint. Without a contrast and its uncertainty, the four means cannot establish whether active stimulation differs from sham stimulation, either overall or within a training condition. The numbered arms are not explicitly mapped to the named combinations in the record, so associating a particular numerical estimate with a particular combination would require information not reported there.

The analysis description is incomplete. The record names covariates but does not specify the model, clarify whether the posted means are adjusted, or describe diagnostics and assumptions. It does not report a statistical analysis plan, multiplicity handling, missing-data methods, or analysis populations. The reasons the arm-level outcome counts differ from overall enrollment are not reported in the registry record.

The endpoint is a specific face-name memory task measured at post-session 5. The record does not report a clinically meaningful threshold, individual outcome distributions, or longer-term results for this endpoint. Although the study description mentions real-world memory testing and brain imaging, those aims do not supply evidence about the primary outcome’s relation to daily functioning or the proposed mechanism.

The registry notes that data coding errors were identified and accurate values were reported 2/6/2023, but does not explain the scope of the errors or their implications for other measures. Safety entries list no affected participants in the serious or other adverse-event categories, but detailed definitions and timeframe are not reported. These limitations restrict interpretation of both the outcome estimates and the completeness of the registry record; they do not, on their own, determine the validity of the underlying study.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Promoting Adaptive Neuroplasticity in Mild Cognitive Impairment — NCT02155946.
• Registry record last updated 2023-11-30; status last verified 2023-11.
• Results first posted 2022-09-01.
• 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.

18. Record Summary

The registry record describes NCT02155946, “Promoting Adaptive Neuroplasticity in Mild Cognitive Impairment,” as a completed, randomized, double-blind, parallel study sponsored by the VA Office of Research and Development. Enrollment is recorded as 107. The study includes active or sham tDCS combined with mnemonic strategy training or autobiographical memory recall.

The primary outcome is mean change in face-name memory performance from baseline to post-session 5, day 5 after baseline. The record reports arm-specific means and 95% confidence intervals, but no estimable two-arm comparison for this continuous endpoint. It lists 3 secondary outcomes and records 8 outcome measures. Serious and other adverse events and deaths are recorded as zero in each arm. The record notes data coding errors and states that accurate values were reported 2/6/2023.