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 Effect of Blueberry Supplementation on Alzheimer's Biomarkers (NCT05172128), a na na study. The primary outcome is Change in Blood Neurofilament Light (NfL) Levels as Measured by Blood Biomarker Assay.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05172128 |
| Phase | NA |
| Condition | Mild Cognitive Impairment, Alzheimer Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Duke University |
| Results posted | Yes |
2. Clinical Question
Population
The registry lists mild cognitive impairment and Alzheimer disease as conditions. The study summary describes its focus as people with mild cognitive impairment. Further eligibility details and the characteristics of the participants are not reported in the registry record.
Intervention
Participants received 18 grams of lyophilized blueberry supplement mixed with water twice daily for 12 weeks.
Comparator
No comparator group is reported. The registry describes a single-group study, so the results do not constitute a randomized, like-for-like comparison with a control group.
Primary question
The primary endpoint asks how blood neurofilament light (NfL) levels changed from baseline to 12 weeks, as measured by a blood biomarker assay. The registry record does not report the observed change or its uncertainty.
The study’s stated purpose was to examine the effects of blueberries on neuronal, glial, and pathology blood biomarkers in mild cognitive impairment, and to estimate sample size for future confirmatory studies. The summary names NfL, glial fibrillary acidic protein (GFAP), Aß40, Aß42, p-tau181, and cytokines as biomarkers measured using an ultrasensitive immunoassay.
The question is therefore about biomarker measurements over time during supplementation, not a comparison of clinical outcomes between assigned treatments. Without a reported control group, a change from baseline would not by itself separate a supplementation-associated pattern from other changes over time. The record does not report the eligibility criteria, the number of people who completed the intervention, or the characteristics of the analyzed population. Those details matter when judging which people the measurements represent and how broadly the findings might apply.
3. Trial Design
The registry describes a completed, single-group study with an enrollment of 12. Allocation is listed as NA, and masking is listed as none. The registry records Duke University as the sponsor. The start date is 2022-02-21, and the primary completion date is 2023-02-06.
All participants were assigned the same intervention as described in the registry: 18 grams of lyophilized blueberry supplement mixed with water twice daily for 12 weeks. There is no reported control arm or randomized treatment allocation. The registry therefore does not support interpreting the study as a controlled treatment comparison. Its within-group focus is consistent with the stated aim of observing blood-biomarker changes and informing sample-size planning for future confirmatory studies.
The primary endpoint is change in blood NfL from baseline to 12 weeks. The measure is continuous, expressed in pg/mL, and the registry lists the mean as its parameter and the standard error as its dispersion. The record lists 7 outcome measures and 5 analyses, but does not report their complete definitions or the analysis details needed to understand how each was handled.
The status is completed, but completion status does not itself provide outcome results. The primary endpoint’s numerical result, its confidence interval, and its test result are not reported in the registry record. Participant flow, adherence, reasons for withdrawal, and the number included in each analysis are also not reported in the registry record. The record does not report a protocol, a detailed statistical analysis plan, a sample-size justification for the study itself, or whether any interim analyses were planned or conducted.
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
| Stage | Single Arm Blueberry Supplementation |
|---|---|
| STARTED | 12 |
| COMPLETED | 10 |
| NOT COMPLETED | 2 |
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 | Single Arm Blueberry Supplementation |
|---|---|---|
| Participants analysed | 10 | |
| Age, Continuous | years | 80.20 (SD 5.16) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 10 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 10 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 10 |
| Education | years | 18.10 (SD 2.15) |
| Mini-Mental State Examination (MMSE) | units on a scale | 27.20 (SD 2.15) |
| Weschler Logical Memory Delay | units on a scale | 4.80 (SD 3.43) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Blood Neurofilament Light (NfL) Levels as Measured by Blood Biomarker Assay, measured over Baseline, 12 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Error |
| Unit | pg/mL |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in blood neurofilament light (NfL) from baseline to 12 weeks, measured by a blood biomarker assay and expressed in pg/mL. NfL is included in the study summary among the neuronal blood biomarkers of interest. The endpoint is continuous, and the registry identifies the mean as the parameter and the standard error as the dispersion.
In general, a biomarker endpoint gives a measurable biological signal that can be compared across time points. A change score focuses on how measurements differ within the study period, while a group mean describes the average pattern in the analyzed group. Such measures can be useful in early studies that seek to characterize biomarker responses and plan later research. They are not, by themselves, evidence of a change in symptoms, daily function, or disease course.
The registry does not report the observed mean change in NfL, the number of participants with usable measurements at both time points, or a confidence interval. Without those results, the direction, magnitude, and precision of the endpoint cannot be assessed from the record. The description also does not provide assay performance details or specify how missing measurements were handled; those items are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The main interpretive constraint is the absence of reported primary-outcome results. Although the study is marked completed and identifies a change in blood NfL as its primary endpoint, the registry record does not report the estimated change, a confidence interval, or a statistical test result. It is therefore not possible to characterize the observed direction, size, or precision of the primary endpoint from the registry record.
The design also limits what any within-group change could establish. Participants received the same supplementation, and no comparator group is reported. In general, repeated measurements in a single group can describe what changed during a study period, but cannot isolate the intervention as the cause of a change. Time, measurement variability, participant-level changes, and other influences are not separated by a concurrent control comparison. This is especially important when interpreting a biological measurement: a change in a biomarker is not automatically a change in a clinical outcome.
The record’s stated purpose includes estimating sample size for future confirmatory studies. Planning illustrations based on an observed effect are not observed power and do not establish that a future study will detect an effect. Their usefulness depends on the reliability of the estimated effect and the assumptions used in the planning calculation. The record describes the planning assumptions as a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Those are planning assumptions, not evidence that this single-group study used those design features.
Precision cannot be judged without an estimate and its uncertainty. In general, a confidence interval describes a range of values compatible with the data under the analysis assumptions; a narrower interval indicates greater precision than a wider interval. No primary-endpoint confidence interval is reported in the registry record. The standard error is named as the dispersion measure, but its numerical value is also not reported for the endpoint.
The registry lists 7 outcome measures and 5 analyses, but does not provide the full outcome results or a detailed account of analysis choices. There is no reported description of adjustment for multiple comparisons, the analysis population, or missing data handling. These omissions prevent a reader from assessing whether the analysis followed a prespecified plan or how much the results might depend on analytic decisions.
The safety figures are descriptive registry entries, not a comparison against another group. They do not, on their own, establish whether an event was caused by the supplement. Further details about event timing, severity beyond the serious classification, and relatedness are not reported in the registry record. Taken together, the available information describes the study’s aims, design, endpoint, and some safety counts, but does not provide the primary result needed to evaluate the biomarker change.
9. Statistical Methods Explained
The registry frames the primary outcome as a mean change in a continuous measure. A continuous measure can take values along a scale rather than being limited to categories. Here, the scale is blood NfL in pg/mL, measured at baseline and 12 weeks. The target summary is the average change over that interval in the analyzed group. The record does not report the numerical mean change or the number of observations used to estimate it.
What does the standard error describe?
In general, a standard error describes the sampling precision of an estimated statistic, such as a mean. It reflects how much an estimate would vary across repeated samples under the assumptions of the statistical model. It is not the same as the spread of individual measurements: a group can contain highly variable individual values while the estimated mean has a different degree of precision. The registry identifies standard error as the dispersion measure for the primary endpoint, but the numerical standard error is not reported in the registry record.
A confidence interval is another way to express uncertainty around an estimate. In general, it gives a range of values that are compatible with the observed data under the chosen method and its assumptions. It helps readers distinguish a precise estimate from one that remains uncertain. A confidence interval for the primary endpoint is not reported in the registry record, so its precision cannot be evaluated from the posted results.
What can a before-and-after measure establish?
A baseline-to-follow-up change describes the pattern between measurements in the study group. It does not provide the counterfactual comparison needed to determine what would have happened over the same period without the intervention. In general, a randomized concurrent comparison can help separate treatment-group differences from shared time effects and other influences. This record is listed as single-group, with allocation NA and no comparator; accordingly, no like-for-like control comparison is available in the registered design.
The word “change” also depends on how measurements were paired and analyzed. The registry says that the endpoint is change from baseline to 12 weeks, but does not report the exact analysis procedure, handling of incomplete pairs, or whether covariates were used. Those details are not reported in the registry record. It would be inappropriate to infer a test, model, or adjustment from the endpoint description alone.
How should planning illustrations be read?
The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They describe detecting a stated fraction of the observed effect. These assumptions concern planning illustrations for future research; they do not describe the actual single-group intervention design. In general, a planning calculation translates assumptions about an effect and variability into an illustration of the participants needed under a specified design. Changing the assumed effect or design can change that illustration.
Such calculations should not be called observed power. Observed power is not a substitute for reporting the effect estimate and its uncertainty. The record says the sample-size illustrations are computed from the observed effect, but the actual primary endpoint result and the numerical planning outputs are not reported in the registry record. The planning estimates should therefore be treated as design illustrations, not as evidence that the study had a particular ability to confirm an effect.
The registry notes that time-to-event planning tables use total events, while other planning tables use participants per arm. The primary endpoint in this study is a continuous biomarker change, not a time-to-event endpoint. Because no numerical planning output is included in the registry record, no sample-size value can be interpreted from the registry entries.
What is not specified about the analyses?
The registry lists 5 analyses and 7 outcome measures, but that count does not reveal which statistical tests or models were used, whether analyses were prespecified, or how the outcomes were prioritized beyond the identified primary endpoint. The record does not report a detailed statistical analysis plan, an interim-analysis plan, adjustment for multiple comparisons, or a sample-size justification for the study itself. Those choices can affect interpretation and should not be reconstructed from the study’s general aim or outcome descriptions.
In general, transparent reporting connects each endpoint to its analysis population, estimator, uncertainty measure, and missing-data approach. It also makes clear whether analyses were planned in advance or exploratory. The registry information available for this study identifies the primary measure and its summary type, but leaves those additional methodological details unreported. As a result, the design can be described, while the statistical implementation and the evidential strength of the primary finding cannot be assessed from the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 7 outcome measures and 5 analyses. It identifies change in blood NfL as the primary endpoint, but does not report the complete analysis plan or explain how the other outcomes and analyses were prioritized. Adjustment for multiple comparisons is not reported in the registry record.
Multiplicity matters in general when several outcomes or analyses are examined: the chance of finding an apparently notable result can increase when many results are considered. Methods to address this depend on the research question and the prespecified analysis strategy. Since the record does not describe such a strategy, it is not possible to determine whether or how multiplicity was handled. The number of listed outcomes and analyses alone does not establish that a particular adjustment was needed or used.
Missing-data handling and analysis populations are also not reported in the registry record. The entry does not specify how many participants contributed baseline and 12-week measurements, whether all enrolled participants were included in the primary analysis, or what happened if a measurement was unavailable. In general, missingness can affect both the estimate and its precision, depending on why observations are absent and how the analysis treats them. No method should be inferred from the endpoint description.
The record also does not report participant flow, adherence, or reasons for withdrawal. Without these details, it is not possible to assess whether the analyzed observations represent all participants who began the study or whether missing follow-up could affect interpretation. The primary result itself is not reported, further limiting any evaluation of the analysis.
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 |
|---|---|---|---|
| Blueberry Supplementation | 1 | 10 | 10.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Blueberry Supplementation | 0 of 10 |
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 |
|---|---|
| Blueberry Supplementation | 5 of 10 |
Most frequent serious adverse event terms
| Event term | Organ system | Blueberry Supplementation |
|---|---|---|
| altered mental status | Nervous system disorders | 1 of 10 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Blueberry Supplementation |
|---|---|---|
| constipation | Gastrointestinal disorders | 2 of 10 |
| diarrhea | Gastrointestinal disorders | 1 of 10 |
| tremor/weakness | Nervous system disorders | 1 of 10 |
| Covid infection | Infections and infestations | 1 of 10 |
| hematemesis | Gastrointestinal disorders | 1 of 10 |
| abdominal pain | Gastrointestinal disorders | 1 of 10 |
Serious events with the highest arm-level rate: altered mental status (10.0%).
The registry lists a serious adverse event group titled “Blueberry Supplementation.” It reports 10 at risk and 1 affected for serious events, with 0 deaths. The listed top serious term is altered mental status, with 10.0% reported. The entry also reports 10 at risk and 5 affected for other adverse events.
These figures are descriptive counts in the registry record. They do not establish that an event was caused by the supplement, and the record does not provide a comparator group for assessing relative event rates. The serious-event count and the other adverse-event count should be read as separate categories as recorded; the registry does not explain whether events or affected participants overlapped across categories.
The listed percentage for altered mental status is reported as a top serious term, but the record does not provide further detail about the event, its timing, its severity beyond its serious classification, or its assessed relationship to the intervention. The registry does not report fuller safety narratives or a comparative safety analysis. These entries should therefore be treated as a limited description of recorded events, not as a causal conclusion.
12. What the Result Does, and Does Not, Mean
The registry record documents a completed, single-group study intended to examine blood biomarkers during 12 weeks of lyophilized blueberry supplementation and to inform sample-size planning for future confirmatory research. It identifies change in blood NfL from baseline to 12 weeks as the primary endpoint. It also describes the supplement schedule and reports selected adverse-event counts.
The record does not report the numerical result for the primary endpoint. Consequently, it does not establish whether mean NfL increased or decreased, how large any observed change was, or how precisely that change was estimated. It also does not report a confidence interval or a test result for that endpoint. A completed status is not a substitute for outcome data.
Even if a before-and-after biomarker change were available, a single-group design would not by itself establish that supplementation caused it. The study has no reported control group, so changes over time and other influences cannot be separated from the intervention. A biomarker measurement is also not the same as a clinical outcome. The registry does not report results for symptoms, function, or disease progression, and no conclusion about those outcomes can be drawn from the biomarker endpoint description.
The sample-size planning purpose should be interpreted as exploratory preparation for future research. Planning illustrations based on an observed effect are not observed power and do not confirm an effect. Their value depends on the estimate and assumptions behind them. Since the endpoint result and numerical planning outputs are not reported in the registry record, those aspects cannot be evaluated.
The record gives a limited safety description but does not provide a comparative analysis or sufficient event detail to attribute events to the intervention. Overall, the registry supports describing the study’s design and intended measurements, but not a conclusion about the effect of supplementation on NfL or other biomarkers, or about clinical benefit or harm.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of a biomarker-focused, single-group design with an explicit future-planning aim. The record identifies a continuous primary endpoint, a defined measurement interval, and a summary target: mean change in blood NfL from baseline to 12 weeks. It also states that the study was intended to help estimate sample size for future confirmatory studies. These features make clear that the study’s role is exploratory rather than a randomized comparison of treatments.
That distinction matters when reading observed changes. In general, a single-group before-and-after study can characterize measurements over time, but the absence of a control group limits causal interpretation. Future confirmatory work would need a design and analysis appropriate to its question; the record does not specify such a future protocol. It also does not report enough information to judge the precision of the present primary estimate or the reliability of any planning value.
The study also illustrates the importance of complete results reporting. A completed study record can identify its endpoint and intervention while leaving the central numerical result, uncertainty, analysis population, and missing-data methods unreported. Without these, readers cannot evaluate the size or precision of the biomarker change, nor how robust the analysis may be to incomplete follow-up or analytic choices.
Finally, the presence of several outcomes and analyses makes transparent reporting of multiplicity and prespecification relevant. The registry lists their counts but does not report how they were handled. The statistical importance of this study therefore lies in its stated biomarker and planning objectives, as well as the limits imposed by a single-group design and missing result details.
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 trial-specific limitation is that no comparator group is reported. The study is listed as single-group, with allocation NA and no masking. Any within-group change would be descriptive and would not, without a control comparison, isolate the intervention from other influences over time.
The registry record does not report the primary endpoint estimate, its standard error, a confidence interval, or a statistical test result. This prevents assessment of the direction, magnitude, and precision of the primary finding. Although the study is marked completed, the primary result is not reported in the registry record.
Enrollment is listed as 12, but the number with measurements at both baseline and 12 weeks, the number included in each analysis, participant flow, and reasons for withdrawal are not reported. The record does not describe adherence to the twice-daily supplement schedule or how missing measurements were handled. These omissions limit assessment of how the analyzed data relate to the enrolled group.
The entry names several biomarkers and lists 7 outcome measures and 5 analyses, but does not provide the full results or detail how outcomes were prioritized and analyzed. Multiplicity handling, the analysis population, and the detailed statistical plan are not reported in the registry record. Eligibility criteria and participant characteristics are also not reported, limiting assessment of whom the findings might represent.
Safety reporting is limited to the listed counts and serious-event term. The registry does not provide fuller event narratives, timing, or relatedness assessments. The record also does not report assay performance details. These gaps restrict interpretation of both the biomarker measurements and the safety entries, independently of the design’s lack of a comparator.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effect of Blueberry Supplementation on Alzheimer's Biomarkers — NCT05172128.
- Registry record last updated 2024-09-19; status last verified 2024-09.
- Results first posted 2024-09-19.
- 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 registry describes a completed, single-group study sponsored by Duke University, with enrollment of 12. Participants received 18 grams of lyophilized blueberry supplement mixed with water twice daily for 12 weeks. The study summary describes an aim to examine neuronal, glial, and pathology blood biomarkers in mild cognitive impairment and to inform sample-size planning for future confirmatory studies.
The primary endpoint is mean change in blood NfL from baseline to 12 weeks, measured in pg/mL. The registry lists standard error as the dispersion measure. It does not report the primary endpoint result or its uncertainty. There is no reported comparator group, and allocation is listed as NA.
The record lists 7 outcome measures and 5 analyses, but does not report the detailed statistical plan, multiplicity handling, analysis populations, or missing-data methods. Safety entries include serious and other adverse-event counts and a top serious term. The available information describes the design and intended measurements but is insufficient to evaluate the primary biomarker result or draw a causal conclusion.