This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Heart Rate and Breathing Effects on Attention and Memory (NCT05602220), a randomized na study. The primary outcome is Change in Plasma Amyloid Beta (Aβ) Levels.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05602220 |
| Phase | NA |
| Condition | Aging, Alzheimer Disease, Age-related Cognitive Decline |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 91 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Southern California |
| Results posted | Yes |
2. Clinical Question
Population
The study summary describes healthy adults aged 50-70 who meet eligibility criteria. The registry lists aging, Alzheimer disease, and age-related cognitive decline as conditions of interest. The number of participants meeting each eligibility or condition category is not reported in the registry record.
Intervention
Both conditions pair daily memory and attention training with paced breathing at home. One breathing protocol is intended to increase alertness; the other is intended to increase relaxation. The summary describes 10 weeks of brain training starting in Week 2 and 9 weeks of paced breathing starting in Week 3.
Comparator
The two randomized conditions are compared with each other: training followed by breathing intended to stimulate alertness versus training followed by breathing intended to relax. The registry record does not describe a no-training or no-breathing control group.
Primary question
The primary endpoint is change in plasma amyloid beta (Aβ) levels, represented by an aggregate Z-score. The planned question is whether the change across Week 2, Week 7, and Week 12 differs by breathing condition. Although the record describes this comparison, its numerical outcome results and inferential test results are not reported in the registry record.
The question is about a difference in trajectories between the two conditions, not simply whether the average value changes over time in either condition. A time-by-condition interaction is the registry’s stated test of that question: it assesses whether the pattern of change across the three visits differs between the alertness and relaxation conditions. The posted record does not report the estimated changes, uncertainty intervals, or interaction test result, so the direction, size, and precision of any between-condition difference cannot be assessed from the registered results.
3. Trial Design
The registry describes a randomized, single-masked, parallel-group behavioral study. Participants were assigned to one of two conditions, and the study is recorded as completed. The registry lists an enrollment of 91. The number analyzed for the primary outcome, and how the enrollment relates to the outcome-specific analysis groups, are not reported in the registry record.
The study began on 2023-01-11, with primary completion recorded as 2023-11-06. The registry lists phase as NA. These design and status details describe the registered study; they do not establish that every participant completed every intervention or assessment. Completion status alone does not provide information about adherence, withdrawals, or the availability of blood samples at each visit.
The brief description says participants were to complete online cognitive testing before and after the intervention, practice brain training at home, and follow a paced-breathing protocol at home. It also describes laboratory visits in Weeks 2, 7, and 12 for blood and urine sampling and magnetic resonance imaging. The primary measure is based on blood draws at those visits. The registry lists secondary outcomes concerning perivascular space volume, hippocampal volume, and performance on 12 Lumosity games.
Randomization is intended to make treatment groups comparable on average at the start of a study, while masking is intended to reduce certain kinds of bias. The identity of the masked party and details of how randomization and masking were implemented are not reported in the registry record. The record also does not report a statistical analysis plan or details of the allocation procedure. Therefore, the design label alone cannot establish how these protections operated in practice.
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: Out of the 91 participants enrolled, 10 dropped after enrolling but before Week 1 home assessments, and an additional 19 dropped before condition assignment.
Overall Study
| Stage | Brain Training and Paced Breathing to Stimulate Alertness | Brain Training and Paced Breathing to Relax |
|---|---|---|
| STARTED | 31 | 31 |
| COMPLETED | 29 | 31 |
| NOT COMPLETED | 2 | 0 |
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.
| Characteristic | Unit | Brain Training and Paced Breathing to Stimulate Alertness | Brain Training and Paced Breathing to Relax | Total |
|---|---|---|---|---|
| Participants analysed | 31 | 31 | 62 | |
| Age, Continuous | years | 59.77 (SD 6.17) | 60.52 (SD 5.42) | 60.15 (SD 5.77) |
| Sex: Female, Male: Female | Participants | 17 | 17 | 34 |
| Sex: Female, Male: Male | Participants | 14 | 14 | 28 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 7 | 4 | 11 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 23 | 26 | 49 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 5 | 7 | 12 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 5 | 2 | 7 |
| Race (NIH/OMB): White | Participants | 16 | 18 | 34 |
| Race (NIH/OMB): More than one race | Participants | 2 | 3 | 5 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 3 | 1 | 4 |
| Region of Enrollment: United States | participants | 31 | 31 | 62 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Plasma Amyloid Beta (Aβ) Levels, measured over Measured from blood draws at lab visits on Weeks 2, 7, and 12.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Z-score |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in plasma amyloid beta (Aβ) levels, expressed as an aggregate Z-score based on plasma Aβ40 and Aβ42 concentrations. The registry states that a Z-score of 0 represents the sample mean and that higher values indicate greater plasma Aβ. The score combines information from the two listed forms of Aβ into a standardized measure; the exact calculation and any reference distribution are not reported in the registry record.
Measurements are scheduled at Week 2 before the intervention, Week 7 during the intervention, and Week 12 after the intervention. The record describes comparing the score across these three times and testing whether the pattern over time differs between the two conditions. Repeated measurement allows the analysis to consider change rather than relying only on a single post-intervention value.
The registry description gives a rationale for measuring plasma Aβ: it states that higher levels in cognitively normal individuals have been associated with greater risk of conversion to Alzheimer’s disease. This is background context for the endpoint, not evidence that a change in this trial predicts an individual’s future health or establishes a clinical effect. The endpoint is a biomarker measured in blood, and the registry does not report the observed values, estimated changes, or their uncertainty.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary outcome and describes the intended comparison, but it does not report numerical primary-outcome results. In particular, the posted record does not give group means or standard deviations at Week 2, Week 7, or Week 12; an estimated time-by-condition effect; a confidence interval; or a p-value for the interaction. The direction and magnitude of the observed outcome pattern are therefore not reported in the registry record.
The distinction between the planned question and a reported result matters. A time-by-condition analysis asks whether the average outcome trajectory differs between the alertness and relaxation conditions. A change within one condition, considered alone, would not answer that comparative question. Nor would a difference at one visit necessarily establish that the overall pattern across all three visits differed. The registry describes the intended interaction test but provides no result with which to evaluate it.
A confidence interval, when reported, conveys a range of values compatible with the data and the statistical model, subject to its assumptions. It helps readers judge how precisely a difference has been estimated. No interval is reported for the primary comparison. A p-value, when reported, describes how unusual the data or a more extreme result would be under a specified null model; it is not a measure of the size or clinical importance of an effect. The registry record does not report a primary-outcome p-value.
The record lists enrollment of 91, but that figure is not the same as the number contributing usable measurements to each visit or to the primary analysis. Outcome-specific participant counts and the handling of missing visits are not reported in the registry record. The adverse-event listing gives at-risk counts for its safety summaries, but those counts do not establish the primary endpoint analysis population.
Accordingly, the registered information supports a description of the study question and measurement schedule, not a conclusion about whether the conditions differed in plasma Aβ change. Without estimates and their uncertainty, readers cannot assess the size, precision, or consistency of the primary outcome pattern. No clinical interpretation of an unreported result is warranted.
9. Statistical Methods Explained
The statistical method described for the primary endpoint is a time-by-condition analysis of variance (ANOVA). The outcome is a continuous aggregate Z-score, and measurements are scheduled at three visits. The intended analysis tests whether the pattern across visits differs between the two randomized conditions. The registry record does not report the fitted model, its test statistic, degrees of freedom, p-value, effect estimate, confidence interval, or assumptions checks.
What does a time-by-condition interaction ask?
In general, an interaction tests whether the association between one factor and an outcome depends on another factor. Here, time is one factor and randomized condition is the other. A time-by-condition interaction asks whether the average change over the measured visits is different for the alertness condition than for the relaxation condition. It is not the same as asking whether there is any change over time in the participants considered together, or whether the conditions differ at a single visit.
In general, an ANOVA separates variation associated with factors in the model from variation among observations not explained by those factors. For repeated measurements, the same participant contributes observations at multiple times, so those measurements are related rather than independent. Appropriate analysis must account for that dependence. The registry says that a time-by-condition ANOVA was conducted, but does not describe its repeated-measures structure, covariance assumptions, corrections, or other implementation details. Those details are not reported in the registry record.
What does the Z-score represent?
In general, standardization expresses a measurement relative to a reference mean and spread. The registry specifies that the aggregate score is based on plasma Aβ40 and Aβ42 and that zero represents the sample mean; higher scores indicate greater plasma Aβ. It does not report the precise formula, the sample used to set the reference mean and spread, or whether the standardization was performed separately by visit or across visits. Those choices can affect how a standardized score is interpreted, so the registry description does not permit reconstruction of the endpoint from raw concentrations.
How should uncertainty be considered?
In general, an effect estimate describes the magnitude and direction of a comparison, while a confidence interval communicates its statistical precision under the analysis assumptions. The p-value addresses compatibility between the observed data and a specified null hypothesis; it does not quantify effect size or establish practical importance. Because no estimate, interval, or primary p-value is reported, the primary comparison cannot be judged for either magnitude or precision from the registry results.
The record also does not state whether the analysis used all randomized participants, only participants with complete measurements, or another analysis population. It does not describe adjustment for baseline values, missing-data methods, transformations, or sensitivity analyses. These are not minor substitutes for results: they determine how the reported estimate would be formed and how robustly it could be interpreted. None of these details should be inferred from the broad ANOVA description.
What can planning calculations tell readers?
In general, a sample-size calculation is a planning illustration tied to assumptions about an effect, variability, allocation, and a statistical test. It is not an observed outcome and does not show what the trial found. The record’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation, with effects expressed as fractions of an observed effect. Such illustrations are not a substitute for the trial’s own planned sample-size justification, which is not reported in the registry record. They also are not observed power, and cannot establish whether a result was conclusive.
The registry notes that the primary outcome has several time points and is not reduced to one comparison in the posted analysis. This is consistent with the longitudinal question, but leaves the numerical evidence unavailable. The record lists seven outcome measures and five analyses. It does not report how those analyses were related, whether a testing hierarchy was specified, or whether any multiplicity adjustment was used. General concerns about multiple testing therefore apply as questions for interpretation, not as claims that a particular adjustment was or was not performed.
10. Multiplicity, Missing Data and Analysis Populations
The primary endpoint is described at three time points, with the central question framed as a time-by-condition interaction. The registry record does not report a numerical result for that interaction or a multiplicity strategy. It also lists seven outcome measures and five analyses, but does not explain how the outcomes and analyses were organized, which were confirmatory, or whether adjustment for multiple comparisons was planned or applied. The effect of multiplicity on the interpretation of the reported findings is therefore not reported in the registry record.
In general, testing multiple hypotheses can increase the chance of obtaining at least one apparently notable result by chance. Adjustments or a prespecified hierarchy can help control that risk, but their appropriateness depends on the study questions and analysis plan. No particular approach should be attributed to this trial without a registry description.
The registry identifies scheduled assessment visits but does not report outcome-specific numbers observed at each visit, missingness by condition, reasons for missing data, or the method used to handle missing measurements. It is therefore unclear from the registry record whether the primary analysis included participants with incomplete follow-up, required complete data, or used another method. In general, missing-data approaches rely on assumptions about why observations are missing; those assumptions and any sensitivity analyses are not reported.
The record also does not identify the primary analysis population or say whether participants were analyzed according to randomized condition. Although enrollment is recorded as 91 and adverse-event summaries list 31 at risk in each condition, these figures do not establish the population used for the primary endpoint analysis. The analysis population and its relationship to randomization are not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Brain Training and Paced Breathing to Stimulate Alertness | 0 | 31 | 0.0% |
| Brain Training and Paced Breathing to Relax | 0 | 31 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Brain Training and Paced Breathing to Stimulate Alertness | 0 of 31 |
| Brain Training and Paced Breathing to Relax | 0 of 31 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Brain Training and Paced Breathing to Stimulate Alertness | 3 of 31 |
| Brain Training and Paced Breathing to Relax | 3 of 31 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Brain Training and Paced Breathing to Stimulate Alertness | Brain Training and Paced Breathing to Relax |
|---|---|---|---|
| bruising following a blood draw | Blood and lymphatic system disorders | 2 of 31 | 2 of 31 |
| light-headedness during home practice | Respiratory, thoracic and mediastinal disorders | 0 of 31 | 1 of 31 |
| Discomfort during MRI due to body size | General disorders | 1 of 31 | 0 of 31 |
The adverse-event listing reports zero serious adverse events in each condition and zero deaths in each condition. It also lists three other adverse events in each condition. The at-risk count shown for these safety summaries is 31 in each condition. These are the counts recorded in the registry; they should not be read as the primary outcome sample sizes.
The record does not identify the types of the other adverse events, their severity, timing, relationship to the study activities, or whether any participant experienced more than one event. It also does not provide further detail about how events were collected or classified. Therefore, the listing supports only a narrow description of the reported counts, not an assessment of the nature or cause of those events.
In general, adverse-event counts are descriptive safety information. They do not by themselves establish whether an event was caused by an intervention, and zero recorded serious events does not prove that no risk exists. The registry record’s completed status and its event counts do not replace the missing detail about event types, follow-up, or ascertainment. The counts should be interpreted as registry-reported summaries rather than as a comprehensive safety analysis.
12. What the Result Does, and Does Not, Mean
The registered study compares two behavioral conditions that both pair brain training with paced breathing. Its primary question concerns whether plasma Aβ Z-score changes differently over time between breathing intended to stimulate alertness and breathing intended to promote relaxation. The registry describes the endpoint, its scheduled visits, and the planned interaction question. It does not report the primary results.
That absence limits what can be concluded. Without group-level measurements, an effect estimate, and a measure of uncertainty, readers cannot determine which condition had higher or lower values, whether the trajectories differed, or how precisely any difference was estimated. It is not appropriate to characterize the primary result as positive, negative, statistically significant, or null on the basis of the available registry record.
Even if a difference in the biomarker were reported, interpretation would need to distinguish a biomarker result from a direct measure of cognitive function or a clinical outcome. The registry describes plasma Aβ as an endpoint and gives a background rationale for studying it; it does not establish that a change in this score predicts an individual outcome in this study. The record lists cognitive and imaging measures as secondary outcomes, but their numerical results are not included in the information available for this account.
In general, randomized comparisons can support causal interpretation when the design and analysis are implemented appropriately, but details of allocation, masking, adherence, missingness, and analysis populations matter. Several of these implementation details are not reported in the registry record. The registered design alone cannot resolve those uncertainties.
The safest reading is therefore descriptive: the registry records a completed randomized study, two active behavioral conditions, and a longitudinal biomarker question. It does not provide the numerical evidence needed to determine the observed primary comparison or its precision. No conclusion about a treatment effect or clinical benefit follows from the registry information.
13. Why This Trial Matters Statistically
This study is statistically interesting because its primary question is longitudinal and comparative. Rather than asking only whether a biomarker differs at one visit, the stated analysis asks whether its pattern across three visits varies by randomized condition. That distinction focuses attention on the change trajectory and the interaction between time and condition.
The endpoint also illustrates the interpretive care needed for standardized biomarkers. A Z-score can make a combined measure easier to analyze, but its meaning depends on how the score is constructed and what reference distribution is used. The registry explains that zero represents the sample mean and that higher values indicate greater plasma Aβ, while leaving the exact standardization procedure unreported. Readers should not assume more detail than the record states.
The study description includes repeated behavioral practice, blood sampling, imaging, and cognitive assessments. These different measures address different kinds of questions. The primary biomarker endpoint is not interchangeable with cognitive performance or imaging outcomes, and a result in one domain would not automatically establish a result in another. The registry lists secondary outcomes, but does not report their numerical findings in the record described.
Finally, this record illustrates why a clear analysis plan and complete reporting matter. The intended interaction is identified, yet its estimate, uncertainty, missing-data handling, analysis population, and multiplicity approach are not reported in the registry record. Without these elements, readers can understand the question but cannot evaluate the strength or precision of the evidence answering it. The distinction between a well-specified scientific question and an assessable statistical result is central to responsible trial interpretation.
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 main limitation for interpreting this trial from the registry record is the absence of numerical primary-outcome results. No time-specific group summaries, interaction estimate, confidence interval, or p-value are reported. This prevents assessment of the direction, magnitude, and precision of the primary comparison.
The record describes an aggregate Z-score based on plasma Aβ40 and Aβ42, but does not report the exact score construction or reference used for standardization. The analysis is described as a time-by-condition ANOVA, but the repeated-measures specification, model assumptions, and any corrections are not reported. It is therefore not possible to reproduce the stated analysis from the registry description.
Outcome-specific counts at each visit, missing-data reasons and methods, and the primary analysis population are not reported in the registry record. The enrollment figure does not establish how many participants contributed data to each endpoint or analysis. Adherence to the at-home activities and completeness of follow-up are also not reported.
The record does not explain the randomization procedure or identify who was masked. It does not report a multiplicity strategy despite listing seven outcome measures and five analyses. These omissions limit evaluation of possible bias, precision, and the relationship between the primary and other analyses. The adverse-event listing provides counts but not event types or further clinical detail.
These are limitations of the information reported in the registry record; they do not establish that the study itself lacked procedures or analyses addressing these issues. Such procedures, results, and details are simply not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Heart Rate and Breathing Effects on Attention and Memory — NCT05602220.
- Registry record last updated 2026-01-09; status last verified 2026-01.
- Results first posted 2026-01-09.
- 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.
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18. Record Summary
The University of Southern California study, “Heart Rate and Breathing Effects on Attention and Memory,” is recorded as a completed randomized, single-masked, parallel-group behavioral trial. Enrollment is listed as 91. The study began on 2023-01-11, and primary completion is recorded as 2023-11-06.
The two conditions pair brain training with paced breathing intended either to stimulate alertness or to promote relaxation. The primary endpoint is change in an aggregate plasma Aβ Z-score measured at Week 2, Week 7, and Week 12. The registry describes a time-by-condition ANOVA, but the primary numerical results, analysis population, missing-data methods, and multiplicity strategy are not reported in the registry record.
The adverse-event listing records zero serious adverse events and zero deaths in each condition, with three other adverse events in each. The record also lists secondary cognitive and imaging outcomes. Numerical results for those outcomes are not reported in the registry record.