NMDA Receptors in Motor Learning in Humans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for NMDA Receptors in Motor Learning in Humans (NCT02082912), a randomized phase 2 study. The primary outcome is Grip Strength of Affected Hand.

2. Clinical Question

The comparison is designed to examine the addition of D-cycloserine in the setting of robotic therapy. Because the device therapy is included in both arms, the study does not directly compare robotic therapy with no robotic therapy. The primary endpoint is grip strength of the affected hand, recorded in Newtons and described as a mean with standard deviation. The registry says an increase in the measure indicates improving grip strength.

The registry lists stroke as the condition and describes an aim of enhancing upper-limb recovery through robotic-assisted therapy combined with a drug intended to improve motor learning. That statement describes the study rationale, not a demonstrated treatment effect. A numerical comparison of grip strength between groups, including an effect estimate and its uncertainty, is not reported in the registry record. Thus the question can be described from the design, but the posted information does not establish the magnitude or precision of a difference.

3. Trial Design

This is a completed, randomized, double-masked, parallel-group Phase 2 study sponsored by Emory University. Enrollment was 14. The registry gives the start as 2010-06 and primary completion as 2012-04. The condition listed is stroke.

Participants were assigned to D-cycloserine or placebo, and both groups used the HandMentor Pro for robotic therapy. The arm descriptions specify the study drug or placebo pill alongside that device. This shared device therapy makes the planned contrast the drug assignment within a setting where participants receive robotic therapy. It does not isolate the effect of the device itself.

The record identifies the study as double-masked but does not report which people involved in the study were masked, how masking was maintained, or whether masking was assessed. The randomization method, allocation concealment, treatment dose, treatment schedule, duration of drug use, and details of the robotic therapy schedule are not reported in the registry record. These omissions limit the detail available for evaluating how the intervention was delivered and how assignment was implemented.

The primary outcome is grip strength of the affected hand, assessed at baseline and Day 30. The analysis population is described as participants completing the study. The number completing and the number included in the primary analysis are not reported in the registry record. Secondary outcomes named include Stroke Impact Scale categories, depressive symptoms measured with the CES-D, a DETECT system score, and blocks moved in the Box and Block Test of the affected arm. Numerical results for these outcomes 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: A total of 124 patients were screened and of these 14 met enrollment criteria and consented to participate in the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants completing the study are included in this analysis.

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: Only participants that completed the study are included in the baseline analysis.

6. Primary Endpoint

The registry lists the primary outcome as Grip Strength of Affected Hand, measured over Baseline, Day 30.

The primary endpoint is grip strength of the affected hand, measured in Newtons. The registry describes the value as the mean of three trials using a calibrated Jamar dynamometer. The standardized positioning described is an elbow flexed to 90º with the forearm in a neutral position. The registry characterizes this as the method recommended by the American Society of Hand Therapists for measuring hand-grip strength with a Jamar dynamometer.

Grip strength is a continuous measure: it can take a range of values rather than placing participants into categories. Reporting a mean and standard deviation describes the group’s average measurement and the spread of measurements around that average. The stated assessment times are baseline and Day 30. The registry says that an increase in grip-strength values means improvement in grip strength.

Using the affected hand focuses measurement on the limb relevant to the study’s post-stroke motor-recovery rationale. A standardized instrument and positioning can support consistent measurement across assessments. However, the registry record does not report the numerical group means, changes from baseline, a between-group estimate, or uncertainty for the primary outcome. It also does not report how the baseline and Day 30 measurements were combined into a primary comparison. The endpoint definition therefore explains what was measured, but not what the comparison found.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

For a continuous outcome such as grip strength, the mean describes the group’s average measurement. The standard deviation describes how dispersed individual measurements are around that average. These summaries answer different questions: the mean locates the group average, while the standard deviation describes variation among participants. Neither, by itself, gives the uncertainty in a comparison between groups.

A between-group estimate would express the contrast of interest, such as the difference in grip strength under the assigned study regimens. Its interpretation depends on how the endpoint is defined and analyzed. Because the registry names baseline and Day 30 but does not report the chosen comparison, the precise estimand—the quantity the analysis was intended to estimate—is not reported in the registry record.

What would a confidence interval add?

In general, a confidence interval describes the uncertainty around an estimated effect under the assumptions of the statistical method. A narrow interval indicates greater precision than a wide interval, while the interval’s position helps show which effect sizes remain compatible with the data and model. It is not a guarantee that the true effect lies within a particular interval. No confidence interval for the primary comparison is reported in the registry record, so its precision cannot be assessed from the posted information.

A p-value, when reported, describes how compatible the observed data are with a specified null model under the analysis assumptions. It does not measure the size or importance of an effect, and it does not establish that the null model is true or false. No primary-outcome p-value is reported in the registry record. The absence of that statistic should not be filled by inference from enrollment, design labels, or the safety counts.

Why does the analysis time point matter?

Repeated measurement can support several different questions. A comparison of Day 30 values addresses a different quantity from a comparison of change from baseline. A model using measurements across time may also make assumptions about the relationship among repeated measurements. These approaches can yield different estimates and uncertainty. The registry identifies baseline and Day 30 and notes that the primary outcome has multiple categories or time points, but does not provide a single reduced comparison. The exact model, contrast, and handling of within-participant measurements are not reported in the registry record.

When more than one time point or outcome is examined, the chance of obtaining at least one apparently unusual result can increase if each is tested independently. General statistical approaches can account for multiple testing, define a primary contrast in advance, or treat additional analyses as exploratory. The registry record does not report a multiplicity adjustment, a testing hierarchy, or which analyses were designated primary beyond naming grip strength as the primary outcome. It is therefore not possible to determine how multiplicity was handled.

How should the planning illustration be understood?

In general, a sample-size calculation depends on a target effect, outcome variability, a significance threshold, desired power, allocation, and assumptions about the statistical model. Changing these assumptions changes the planning result. The registry’s stated illustration uses a two-sided significance level of 0.05, equal allocation, a normal approximation, and a target effect expressed as a stated fraction of the observed effect. For non-time-to-event outcomes, its convention is participants per arm.

The registry explicitly characterizes this as a planning illustration based on an observed effect, not the trial’s own design. It should not be read as the planned enrollment justification or as observed power. Observed power is not a substitute for interpreting an effect estimate and its confidence interval; a completed study’s results are more directly understood through the estimated effect and its precision. The numerical planning outputs and the effect used to derive them are not reported in the registry record, so no particular sample-size conclusion can be drawn.

What is known about the analysis population?

The primary analysis population is described as participants completing the study. This wording indicates that the analysis was not necessarily defined as every person randomized, but the actual number included and the treatment of participants who did not complete are not reported in the registry record. General methods for missing data include complete-case analysis, imputation, and models that use available repeated measurements; each depends on assumptions. The record does not identify which approach was used, whether any observations were missing, or why any participant might not have contributed a measurement.

These methodological details matter because the meaning of an estimate depends on who was analyzed, how repeated measurements were handled, and how uncertainty was calculated. Randomization describes assignment, but it does not by itself resolve missing-outcome or model-specification questions. Without the analysis plan and numerical outcome results, a statistical interpretation should remain limited to the design and measures documented in the registry.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is named as affected-hand grip strength, with assessments at baseline and Day 30. The registry also says that the primary outcome has several categories or time points and was not reduced to a single comparison. The primary contrast, the statistical model, and any adjustment for multiple testing are not reported in the registry record. The record lists secondary outcomes covering Stroke Impact Scale change criteria, CES-D score, DETECT system score, and Box and Block Test performance, but does not report numerical results or a testing hierarchy for those outcomes.

When investigators examine multiple outcomes, time points, or contrasts, the interpretation of nominal statistical tests can depend on whether multiplicity was addressed. General options include controlling an overall error rate, specifying a hierarchy, or labeling additional analyses as exploratory. The registry does not state whether any of these approaches was used. It is therefore not possible to determine from the record how multiplicity might affect interpretation.

The primary analysis population is described as participants completing the study. The number completing, missing outcome counts, reasons for missingness, and method for handling missing measurements are not reported in the registry record. It is also not reported whether the analysis followed assigned treatment regardless of adherence or used another population definition. These are important distinctions: the analysis population and missing-data assumptions affect what comparison an estimate represents and how confidently it can be interpreted. No analysis plan or numerical primary-outcome result is available in the record to resolve these questions.

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 0% reporting threshold.

The registry lists 7 participants at risk for serious adverse events in the D-cycloserine group and 7 in the placebo group. The number affected was 0 in each group. For other adverse events, 7 participants were at risk in each group and 0 were affected in either group. Deaths were 0 in both groups. No serious adverse-event terms are listed.

These counts describe what the record reports for the participants at risk; they do not establish that an intervention has no safety risk. With limited numbers of participants, uncommon events may not be observed, and zero recorded events does not mean that the underlying event probability is zero. The counts also do not indicate whether the groups differed in event risk in a way that can be estimated precisely.

The adverse-event definitions, collection procedures, observation period, and details about event severity or relationship to treatment are not reported in the registry record. Consequently, the counts should be read as a limited descriptive account, not as a complete characterization of safety.

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

The registry establishes that a randomized, double-masked, parallel-group Phase 2 study compared D-cycloserine plus HandMentor Pro robotic therapy with placebo plus the same device therapy in people after stroke. It also defines affected-hand grip strength, measured at baseline and Day 30, as the primary outcome. These registry entries explain what the study set out to assess.

The registry record does not report a numerical primary-outcome comparison. There is no posted estimate of the difference between groups, no group outcome summary, and no confidence interval or p-value for grip strength. Thus the direction and size of any observed contrast, and the precision with which it was estimated, cannot be determined from the information recorded. A measure’s stated interpretation—higher grip-strength values indicate improvement—does not reveal whether either group changed or whether their outcomes differed.

The design’s shared robotic therapy means that the intended contrast concerns drug assignment in the context of device therapy. It does not by itself answer what would happen without robotic therapy. Moreover, randomization is a design feature, not a result; interpretation also requires outcome data and information about the analysis population, missing measurements, and statistical methods.

The recorded safety counts are zero affected for serious and other adverse events in each group, with zero deaths. These observations should not be translated into a claim that risk is absent. The sample was limited to 14 enrolled participants, and event counts alone cannot establish how well the results would apply to other people or settings.

Overall, the registry supports a careful description of the trial and its available safety counts, but not a conclusion about the primary efficacy comparison. The sample-size calculations are planning illustrations, not evidence of power achieved or a replacement for unreported outcome estimates.

13. Why This Trial Matters Statistically

This study poses a focused statistical contrast: D-cycloserine or placebo was paired with the same HandMentor Pro robotic therapy. In principle, that arrangement targets the incremental contribution associated with drug assignment within a robotic-therapy setting. It does not estimate the effect of robotic therapy itself, because the device was used in both groups.

The endpoint is a continuous measure with a specified instrument, positioning, and repeated-trial average. Those details help define what the measurement represents and support consistent assessment. Yet the record’s mention of baseline and Day 30 also illustrates why an analysis needs a clearly stated contrast: a final measurement, a change from baseline, and a model of repeated measurements are not interchangeable descriptions of an effect.

The study also illustrates the difference between design information and result information. Randomization, masking, and a defined primary outcome are important features, but they do not supply the missing effect estimate or its precision. With enrollment of 14, interpretation would especially benefit from complete reporting of the group summaries, between-group estimate, and uncertainty. Those numerical primary-outcome results are not reported in the registry record.

Finally, the stated sample-size approach is explicitly a planning illustration derived from an observed effect, rather than the trial’s original design rationale. Treating such an illustration as observed power would confuse planning assumptions with evidence from the analysis. This distinction matters whenever small studies are used to motivate further research: planning calculations can inform future design under stated assumptions, while the trial’s outcome data and uncertainty are needed to understand what was observed.

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 most consequential limitation of the registry information is that numerical results for the primary endpoint are not reported in the registry record. Although grip strength is defined and assessment times are named, there is no group-level result or between-group estimate with which to judge direction, magnitude, or precision. The record also notes that the outcome has several categories or time points and is not reduced to a single comparison, leaving the primary contrast unclear.

Enrollment was 14, and the primary analysis population is described as participants completing the study. The number completing and the number analyzed are not reported in the registry record. Missing measurements, reasons for non-completion, and methods for handling missing data are also not reported. These gaps make it difficult to assess how much information contributed to the primary comparison or how the analysis population relates to random assignment.

Important implementation details are absent from the record, including drug dose and schedule, the timing and frequency of robotic therapy, the randomization procedure, and the identities of those masked. These omissions do not show that the procedures were inadequate; they mean that the registry record does not permit detailed evaluation of them.

The available safety account consists of zero affected participants in each group for serious and other adverse events, with zero deaths, among 7 at risk per group for each event category. Definitions, reporting windows, and further event details are not reported. Together with the limited enrollment and absent outcome estimates, these omissions constrain both statistical interpretation and assessment of how broadly the findings might apply.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: NMDA Receptors in Motor Learning in Humans — NCT02082912.
• Registry record last updated 2018-11-07; status last verified 2018-10.
• Results first posted 2015-04-22.
• 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

NMDA Receptors in Motor Learning in Humans is a completed, randomized, double-masked, parallel-group Phase 2 study sponsored by Emory University. Enrollment was 14; the registry gives the start as 2010-06 and primary completion as 2012-04. Participants received D-cycloserine or placebo alongside HandMentor Pro robotic therapy.

The primary outcome was affected-hand grip strength in Newtons, assessed at baseline and Day 30 and described as a mean with standard deviation. The primary analysis population is described as study completers. A numerical primary-outcome comparison, the analysis method, and details about missing data are not reported in the registry record. Serious and other adverse events affected 0 participants in each group, with 7 at risk per group for each category; deaths were 0 in both groups.