Nicotinic Enhancement of Cognitive Remediation Training in Schizophrenia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nicotinic Enhancement of Cognitive Remediation Training in Schizophrenia (NCT02069392), a randomized na study. The primary outcome is MATRICS Consensus Cognitive Battery (MCCB) Composite Score.

2. Clinical Question

The trial’s stated aim was to investigate whether nicotine during cognitive training could accelerate or enhance improvement on cognitive measures, and whether any larger training effects would persist after the intervention. Those aims describe the questions motivating the study; they are not evidence that the effects occurred.

The primary outcome was the MATRICS Consensus Cognitive Battery (MCCB) composite score. The planned assessment schedule included baseline (week 0), weeks 4 and 7 of intervention, end-of-intervention (week 10), and a 4-week follow-up. That schedule makes the scientific question broader than a simple comparison at a single visit: it concerns scores during training, at the end of training, and after training has ended. The registry record does not report a prespecified summary contrast across those measurements, or results for the individual assessment times.

The registry lists other cognitive, functional, psychiatric-symptom, quality-of-life, and training-exercise outcomes. Their presence indicates that the study addressed several domains, but the record does not report a statistical plan describing how those outcomes relate to the primary question.

3. Trial Design

This was a randomized, parallel-group trial with quadruple masking. Participants were assigned to cognitive remediation training with nicotine or cognitive remediation training without nicotine. The registry record reports an enrollment of 31. The adverse-event reporting groups list 14 participants at risk in the nicotine group and 17 in the group without nicotine. These are the denominators shown for safety reporting; the registry record does not describe the participant flow or explain whether those denominators match the analysis population for the primary outcome.

Both groups completed daily Posit Science cognitive remediation training for 10 weeks. Participants in the nicotine group used a nicotine polacrilex lozenge before training twice a week. The stated dose was 2 mg for non-smokers or 4 mg for smokers. Participants in the comparator group used a placebo lozenge before training twice a week. The trial therefore compared nicotine with placebo in the setting of training, rather than comparing training with no training.

The record identifies the trial as completed, with a start date of 2015-01 and primary completion date of 2017-06. Its phase is listed as NA. It names the University of Maryland, Baltimore as sponsor. The registry record does not describe the sequence-generation method, allocation concealment, the people included in quadruple masking, or procedures for maintaining masking. Those details should not be inferred from the masking label alone.

Randomization is intended to make treatment groups comparable at the start of a study, on average, but it does not guarantee that a small trial will have identical groups in every respect. The record does not provide baseline characteristics by group or a participant disposition summary. It also does not state whether the primary-outcome analysis followed the original randomized assignments, included only participants with observed scores, or used another analysis population.

The study collected the primary cognitive measure at multiple timepoints and listed several secondary outcomes. However, the registry record does not report the analysis model, the principal treatment contrast, or a statistical plan for those repeated measurements. The design features identify how the interventions were organized, but the posted record alone does not establish how the outcome data were analyzed.

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

Reasons for not completing this period:

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 MATRICS Consensus Cognitive Battery (MCCB) Composite Score, measured over baseline (week 0), weeks 4 and 7 of intervention, end-of-intervention (week 10), 4-week follow-up.

The primary endpoint was the MATRICS Consensus Cognitive Battery (MCCB) Composite Score, a score on a scale reported as a mean with standard deviation. The MCCB is described in the registry record as an FDA-approved assessment tool for trials of cognition-enhancing treatments in people with schizophrenia. It combines performance across Speed of Processing, Attention/Vigilance, Working Memory, Verbal Learning, Visual Learning, Reasoning and Problem Solving, and Social Cognition.

The composite is standardized to a T-scale using healthy control normative data, with mean=50 and standard deviation=10. Higher scores reflect better performance. A composite can provide an overall summary across several cognitive domains, while domain-specific scores can show whether patterns differ across those areas. The record identifies the composite as the primary outcome, but does not report domain-level results or a rationale for preferring the composite over its component domains.

The scheduled measurements were baseline (week 0), weeks 4 and 7 of intervention, end-of-intervention (week 10), and a 4-week follow-up. Repeated assessment can describe the course of scores over time, including whether group patterns appear to change during training or remain different at follow-up. Interpretation depends on the specified comparison and analysis method, neither of which is reported as a single primary-outcome result in the registry record.

The registry record does not report observed MCCB means, standard deviations, group contrasts, confidence intervals, or p-values. Consequently, the endpoint’s definition and scoring direction can be described, but the posted information does not quantify the trial’s primary cognitive result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a treatment contrast represent?

A treatment contrast compares the outcome under the nicotine-training assignment with the outcome under the placebo-training assignment. For a continuous endpoint such as the MCCB composite, a contrast might be expressed as a difference in mean scores, a difference in change from baseline, or a model-based estimate across repeated visits. These choices answer related but distinct questions. The registry record identifies the outcome and assessment schedule but does not report which contrast was used.

An unadjusted comparison uses the observed group summaries without accounting for other variables. An adjusted model can account for prespecified covariates or repeated measurements, depending on its specification. Neither approach is automatically preferable in every setting; interpretation depends on the study design, the planned estimand, and the assumptions of the model. The registry record does not report an adjusted or unadjusted analysis of the MCCB outcome.

What does a confidence interval add?

A confidence interval describes uncertainty around an estimated effect under the statistical procedure used to construct it. It helps readers distinguish a relatively precise estimate from one compatible with a broad range of effects. The interval’s width depends on factors such as the amount of information in the data and variability in the outcome. A confidence interval does not remove uncertainty, establish clinical importance, or guarantee that the true effect lies within the reported bounds.

No confidence interval for the primary outcome is reported in the registry record. Therefore, the precision of any MCCB treatment contrast cannot be assessed. A p-value, if reported, would address compatibility of the data with a specified null model under its assumptions; it would not by itself show the size or practical importance of an effect. The record does not report a primary-outcome p-value.

How should repeated measurements be considered?

The MCCB was scheduled at baseline (week 0), weeks 4 and 7 of intervention, end-of-intervention (week 10), and a 4-week follow-up. Measurements from the same participant are usually related rather than independent. A repeated-measures method can account for that within-participant relationship and can estimate patterns over time. A simpler analysis might instead compare groups at a selected timepoint or compare change from baseline. The method and contrast affect the interpretation, so knowing the schedule alone is not enough to reconstruct the analysis.

Repeated assessments can also create several possible comparisons: group differences at individual visits, changes between visits, or an overall group-by-time pattern. If many comparisons are examined, some apparently notable results may arise by chance even when no true differences exist. Statistical methods for multiplicity can control or describe that issue, but the appropriate approach depends on which outcomes and contrasts were prespecified. The registry record does not report the trial’s multiplicity plan.

Why does variability matter?

The primary outcome is a continuous score summarized as a mean with standard deviation. The mean describes the average score, while the standard deviation describes the spread of scores around that average. A mean difference can be difficult to interpret without information about variability and precision. Scores may vary across participants even within the same assigned group, and estimates from a small enrolled sample can be sensitive to that variability.

Over-dispersion is a general statistical concept in which observed variability exceeds what a model assumes. It is especially relevant for outcomes modeled as counts or categories, where a simple probability model may understate variation. The primary MCCB composite is continuous, so over-dispersion is not a substitute for assessing its distribution, residual behavior, or model fit. The registry record does not report diagnostic checks or model assumptions for the primary outcome.

How should sample-size illustrations be read?

A planning calculation asks how many participants might be needed under specified assumptions to detect an effect at a chosen significance level and power. The registry record describes an illustrative calculation based on a fraction of the observed effect, a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. Such an illustration is not the trial’s original sample-size justification unless the record says that it was used for planning; the record explicitly describes it as a planning illustration computed from the observed effect, not the trial’s own design.

Participants per arm for 80% power and participants per arm for 90% power, when reported as planning illustrations, are hypothetical planning quantities. They are not observed outcomes and are not evidence that the trial had a particular probability of detecting an effect. The record does not report the numerical planning estimates in the information available for this analysis, and the primary-outcome effect needed to interpret such calculations is not reported as a single comparison. Sample-size illustrations based on an observed effect can also be unstable when the observed effect is imprecise; they should not be read as a substitute for an independently justified design calculation.

For a continuous outcome, the assumed effect and variability influence the required sample size. A smaller target effect or greater variability generally calls for more participants under otherwise comparable assumptions. Those are general statistical relationships, not findings from this trial. The record’s stated normal approximation and equal-allocation assumption describe the illustration’s framework but do not establish that the original trial used those assumptions.

What does recalculation mean?

A recalculated result is a simple, unadjusted derivation from posted summary statistics, rather than the sponsor’s own model-based analysis. It can be useful as a check or an accessible descriptive comparison, but it may not reproduce an analysis that accounts for baseline covariates, repeated measurements, missing observations, or other design features. If recalculated and sponsor-reported results disagree, the sponsor’s own analysis takes precedence for describing the trial’s reported analysis. The registry record does not report a primary-outcome result or a sponsor analysis to compare with a recalculation.

10. Multiplicity, Missing Data and Analysis Populations

The trial lists the MCCB composite as its primary outcome, measured at baseline (week 0), weeks 4 and 7 of intervention, end-of-intervention (week 10), and a 4-week follow-up. It also lists secondary outcomes covering clinical assessments, quality of life, performance-based skills, psychiatric symptoms, training exercise parameters, and working memory. Multiple outcomes and repeated timepoints create multiple possible statistical comparisons. When many tests are performed, the chance of at least one apparently unusual result can increase, even if all null hypotheses are true. This is the general reason that a prespecified testing hierarchy or multiplicity adjustment may matter.

The registry record does not report a statistical plan identifying the primary contrast, ranking the secondary outcomes, or describing an adjustment for multiple comparisons. It also does not report interim analyses or stopping rules. The absence of those details in the registry record does not establish what was or was not done outside the record; the methods are simply not reported in the registry record.

The record does not describe missing-data handling, reasons for missing measurements, or whether outcome data were analyzed for all randomized participants. It does not report the analysis population, the number of participants with MCCB measurements at each visit, or a method for addressing incomplete repeated measurements. These details affect how group summaries and treatment contrasts should be interpreted.

Randomized assignment defines the groups at the start of a trial, but a reported analysis can use different populations depending on the analysis strategy and data availability. Without an account of participant flow and the analysis population, it is not possible to determine from the registry record how closely the outcome analysis reflects all randomized participants. No assumptions about imputation, exclusions, or adherence should be made from the information reported.

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 record lists serious adverse events for 14 participants at risk in the cognitive remediation training with nicotine group and 17 at risk in the group without nicotine. The number with a serious adverse event is 0 in each group. The number with other adverse events is also 0 in each group, and deaths are reported as 0 in both groups.

These figures are event counts within the recorded at-risk groups. They do not measure cognitive outcomes and do not answer whether the intervention changed the MCCB score. They also should not be read as proof that an event cannot occur. With small groups, the absence of a recorded event leaves substantial uncertainty about the range of event rates that could be compatible with the observations.

The registry record does not report event definitions, the observation period for safety collection, event severity categories beyond the serious and other classifications, or details about how events were collected. It lists no top serious-event terms. The reported zero counts can be stated as recorded, but the record does not provide enough context to assess the completeness or sensitivity of safety monitoring.

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

The trial record describes a randomized comparison of cognitive remediation training with nicotine against the same training with placebo. It identifies the MCCB composite as the primary outcome and gives the planned measurement times. It also provides safety counts for the listed groups. These details clarify what the study was designed to examine and what information was recorded.

The record does not report a single primary-outcome comparison, group means, standard deviations, confidence intervals, or p-values. Therefore, it does not permit an estimate of the magnitude or precision of a difference in MCCB scores. It also does not establish whether scores changed differently during training or whether any group pattern persisted at follow-up. The trial’s stated hypotheses should not be treated as results.

The absence of a reported primary comparison is not evidence that the groups were identical, and it is not evidence that one approach was better. It means the registry record does not supply the statistical results needed to distinguish those possibilities. Likewise, the zero adverse-event counts are descriptive safety figures, not proof of the absence of risk or a measure of cognitive effect.

General statistical interpretation requires attention to the endpoint definition, treatment contrast, uncertainty, analysis population, missing measurements, and multiplicity. For this trial, several of those elements are not reported in the registry record. A result at an individual assessment time would not necessarily answer the same question as a prespecified overall trajectory analysis, and a point estimate without an uncertainty interval would not show how precisely the effect was estimated.

The most defensible reading is therefore limited: the registry record documents a completed randomized, quadruple-masked study of nicotine during cognitive training, describes the planned cognitive endpoint, and reports the listed safety counts. It does not provide the outcome analysis required to draw a statistical conclusion about the primary cognitive question. Neither a claim of benefit nor a claim of no effect follows from the missing result.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it combines a continuous cognitive endpoint with repeated assessments over training and follow-up. That structure raises questions about how to summarize a treatment effect: a comparison at the end of training, a difference in change from baseline, and a pattern across all visits represent different estimands. A clear primary contrast is essential for readers to know which question the reported estimate answers.

The intervention also makes the comparator important. Both groups received daily cognitive remediation training for 10 weeks; the distinction was nicotine versus placebo before training twice a week. This design focuses the comparison on adding nicotine in the context of training rather than on training versus no training. Interpretation still depends on the analysis and adherence details, which are not reported in the registry record.

With an enrollment of 31, estimates would be expected to have uncertainty, although the actual precision cannot be determined without outcome variability and results. This is a general statistical consideration, not a calculation of the trial’s power or a judgment about its findings. The listed safety denominators and zero event counts also show why event counts from small groups need cautious interpretation.

The record lists a primary outcome and a range of secondary domains but does not report how repeated testing and multiple outcomes were handled. This makes the distinction between a planned primary question and exploratory findings especially important. Prespecified contrasts and transparent reporting help readers separate the principal test from numerous possible comparisons.

Finally, the record’s sample-size description is a planning illustration based on the observed effect, not the trial’s own design. That distinction matters because a post hoc illustration cannot establish that the study was adequately planned or that it had a particular probability of detecting an effect. The statistical value of the record is clearest in what it documents about design and measurement, while its missing analysis details limit interpretation of outcomes.

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 important limitation for statistical interpretation is that the registry record does not report a single primary-outcome comparison. It identifies the MCCB composite and assessment schedule but provides no group summaries, estimated treatment contrast, confidence interval, or p-value. As a result, the magnitude, direction, and precision of the primary result cannot be evaluated from the record.

The outcome was scheduled at multiple visits, but the record does not identify the primary timepoint or specify whether the analysis focused on a particular visit, change from baseline, or the pattern over time. It does not report a model for repeated measurements or a plan for secondary outcomes. Without those details, readers cannot assess how the analysis matched the study’s stated hypotheses.

The record does not report participant flow, baseline characteristics by group, completion at each visit, adherence to training or lozenges, or the analysis population. It also does not describe missing-data methods, multiplicity handling, or interim analyses. Each of these omissions limits the ability to evaluate the assumptions behind any potential treatment estimate.

Although the study was randomized and quadruple-masked, the registry record does not explain the masking procedures, allocation concealment, or sequence generation. These details are not necessary to identify the broad design, but they would help readers assess implementation. The record also does not provide enough safety-monitoring detail to interpret the zero event counts beyond their recorded denominators and classifications.

Finally, the enrollment was 31, and the adverse-event groups list 14 and 17 participants at risk. The record does not provide a trial-specific sample-size justification. Its stated sample-size calculation is a planning illustration based on the observed effect, not the trial’s own design, and numerical planning estimates are not reported in the record available for this analysis. These limitations prevent reconstruction of the intended statistical plan or a quantitative assessment of the primary outcome.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Nicotinic Enhancement of Cognitive Remediation Training in Schizophrenia — NCT02069392.
• Registry record last updated 2019-09-12; status last verified 2019-09.
• Results first posted 2019-04-08.
• 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

NCT02069392, Nicotinic Enhancement of Cognitive Remediation Training in Schizophrenia, is listed as a completed randomized, parallel-group, quadruple-masked trial sponsored by the University of Maryland, Baltimore. The registry record reports an enrollment of 31 and lists schizophrenia and schizoaffective disorder as conditions.

Both groups completed daily cognitive remediation training for 10 weeks. The intervention group used a nicotine polacrilex lozenge before training twice a week, at 2 mg for non-smokers or 4 mg for smokers; the comparator group used a placebo lozenge. The primary outcome was the MCCB Composite Score at baseline (week 0), weeks 4 and 7, end-of-intervention (week 10), and a 4-week follow-up.

The record does not report a single primary-outcome comparison or its statistical results. It lists 14 and 17 participants at risk for adverse events in the respective groups, with zero serious adverse events, zero other adverse events, and zero deaths reported in each group.