Berries, Bugs, and the Blues: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Berries, Bugs, and the Blues (NCT05817383), a randomized na study. The primary outcome is Depressive Symptom Severity.

2. Clinical Question

The registry record describes a pilot study comparing daily freeze-dried blueberry powder with a nutritionally matched placebo powder. Its primary outcome is change in depressive symptom severity from baseline to 12 weeks, measured with the Center for Epidemiological Studies Depression Scale-Revised (CESD-R). The record also lists gut-microbe abundance and fecal short chain fatty acids as secondary outcomes.

3. Trial Design

This is a randomized, triple-masked, parallel-group pilot study listed as completed in the registry. The phase is recorded as NA. The sponsor is Hebrew SeniorLife. The record lists the study start as 2023-04-05 and primary completion as 2024-07-16. Enrollment is listed as 20. The brief summary, however, refers to “40older, sedentary adults,” and the record does not explain the discrepancy.

Participants were assigned to freeze-dried blueberry powder or placebo powder. The intervention description specifies 48 grams each day for 12 weeks in both arms. The placebo is described as nutritionally matched and devoid of fiber and anthocyanins. The record identifies the design as parallel, meaning the intervention arms are followed as separate groups rather than as a crossover in which participants receive each powder in sequence. Randomization is reported, but the method used to generate or conceal the allocation is not reported in the registry record.

Masking is described as triple. The record does not identify which people or roles were masked, nor does it give further details about how masking was maintained. The primary endpoint is a continuous measure: mean change in CESD-R score between baseline and 12 weeks. The record also lists abundance of microbes and fecal short chain fatty acids, including butyrate, as secondary outcomes. Although three outcome measures are recorded, the posted results include no analyses for the secondary outcomes.

The arm-level primary-outcome summaries give 10 participants for the blueberry arm and 8 for placebo. These figures differ from the enrollment figure and from the safety populations listed in the adverse-event record. The registry record does not explain how the populations for enrollment, outcome reporting, and safety reporting relate to one another.

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

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 Depressive Symptom Severity, measured over Change between baseline and 12 weeks.

The primary endpoint is change in depressive symptom severity from baseline to 12 weeks. The measure is the CESD-R, a self-report scale whose scores range from 0 to 60 points; higher scores indicate more severe depressive symptoms. The registry describes the endpoint as a mean and reports standard deviations for the arm-level changes.

A change score captures how a participant’s measured score at follow-up differs from that participant’s baseline score. Summarizing those changes by an arm mean gives an estimate of the average direction and size of change among the participants included in that summary. The standard deviation describes how spread out individual change scores are around the arm mean; it is not the uncertainty of the mean itself.

Using a defined symptom scale makes it possible to express the outcome consistently across participants and compare the arm summaries. The endpoint is relevant to the study’s stated aim of investigating depressive symptom severity alongside gut microbiota and metabolites. The registry record does not report a threshold for a clinically meaningful change, a minimal important difference, or a protocol rationale for selecting this endpoint. The scale’s range and direction are reported, but the record does not provide enough information to infer how each individual participant changed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is continuous, and the registry identifies its summary measure as a mean with standard deviation. In general, a mean is the arithmetic average of the observations included in a group summary. A standard deviation describes the dispersion of those observations around their mean. A larger standard deviation indicates more spread in the observed values, but it does not directly state how precisely the mean has been estimated. Precision also depends on the amount of information available and is usually conveyed with a standard error or confidence interval.

What does the reported change represent?

Each arm’s endpoint is defined as change between baseline and 12 weeks. The record reports a mean change of -5.0 with standard deviation 3.0 for the blueberry arm, and -4.0 with standard deviation 4.0 for placebo. These are summaries of change, not the baseline or follow-up score distributions themselves. The record does not provide those score distributions, individual participant trajectories, or the method used to handle participants without a measured follow-up score.

In general, an arm-level mean change can describe movement over time among the people represented in that summary. A comparative randomized-trial question usually concerns the difference in outcome between assigned arms, with uncertainty around that estimate. The registry record says the values needed for a two-arm comparison of this continuous endpoint are missing or not estimable. It posts no comparison estimate, confidence interval, or p-value. Consequently, the arm means should not be converted into a claim about a statistically established between-arm effect.

How should uncertainty be understood?

In general, a confidence interval gives a range of values compatible with the data and the method used to calculate it. Its width reflects precision: a wider interval signals less precision, while a narrower interval signals greater precision. A confidence interval is not reported for the primary comparison in this record. Without one, readers cannot use the posted results to judge the range of plausible comparative effects. The standard deviations are not confidence intervals and should not be read as such.

A p-value, when reported, is a measure of how unusual the observed data would be under a specified statistical model and null hypothesis. It does not measure the probability that the null hypothesis is true or the size or importance of an effect. No primary comparison p-value is reported, so a significance conclusion cannot be drawn from the registry record. The record also does not state a statistical model, covariate adjustment, or method for estimating the primary comparison.

What role does the planning illustration have?

The registry describes a sample-size planning illustration based on the observed effect, rather than the trial’s own design. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between arms, a normal approximation, and an effect to detect defined as a stated fraction of the observed effect. Such planning outputs are hypothetical estimates of the sample size that might be needed under those assumptions. They are not observed trial results and are not observed power. The record does not report the trial’s own sample-size justification, so the planning illustration should not be taken as evidence about the original design rationale.

In general, sample-size calculations depend on the assumed effect, outcome variability, allocation, significance level, and target power. If the assumed effect is smaller, more information is generally needed to detect it under otherwise comparable assumptions. A planning result based on an effect observed in a small pilot can be especially uncertain because the observed effect itself may be imprecise. The posted planning assumptions do not resolve the absent formal primary comparison.

Why might dispersion matter?

In general, over-dispersion means that observed variability is greater than a model assumes. When a model underestimates variability, its uncertainty estimates can be too small, which can make results appear more precise than they are. The registry reports standard deviations for the continuous outcome, but it does not report a fitted model or an over-dispersion assessment. The concept is therefore useful background, not a reported feature or finding of this study.

Randomization and masking are design features that can help reduce systematic differences in assignment and outcome assessment. The record states that the study was randomized and triple-masked, but it does not specify the allocation procedure, masking roles, or analysis implementation. Those details cannot be inferred from the design labels alone. Similarly, a parallel design identifies the broad structure of the comparison, but does not specify the statistical model used to analyze the outcome.

The registry reports zero posted analyses. That means the arm-level summaries are not accompanied by a reported inferential analysis in the record. The numerical summaries remain informative descriptions, but they do not substitute for a prespecified or otherwise documented estimate of the primary between-arm contrast and its uncertainty.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Freeze-dried Blueberry Powder", "Placebo Powder")
n   <- c(10, 8)
m   <- c(-5, -4)
sp  <- c(3, 4)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Freeze-dried Blueberry Powder  10  -5.000  3.000  -7.146  -2.854
CARM  Placebo Powder  8  -4.000  4.000  -7.344  -0.656

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures, including depressive symptom severity and secondary outcomes of microbe abundance and fecal short chain fatty acids. It reports two secondary outcomes but no analyses for them. The posted record does not describe a multiplicity strategy, such as whether any outcome was designated for confirmatory testing or whether adjustment across outcomes was planned. Without that information and without posted secondary analyses, the secondary outcomes cannot be used to support a comparative conclusion.

Missing-data handling is not reported in the registry record. It does not state how many participants had endpoint measurements available for each outcome, why any measurements might be unavailable, or whether missing values were imputed or otherwise addressed. The reported outcome counts are 10 for the blueberry arm and 8 for placebo, while enrollment is listed as 20; the safety record lists different populations. The record does not explain these differences or define the analysis population.

The registry does not state whether the primary analysis followed an intention-to-treat principle, included only participants who completed the intervention, or used another population definition. It also does not report protocol deviations, adherence information, exclusions, or sensitivity analyses. These omissions matter because the interpretation of a randomized comparison depends in part on which participants and measurements are included and how missing outcomes are handled. No such choices should be inferred from the available arm summaries.

12. 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’s safety entries list zero serious adverse events in the freeze-dried blueberry powder group, among 10 participants at risk, and zero in the placebo group, among 9 participants at risk. It also lists zero other adverse events in the corresponding groups, with 10 and 9 participants at risk, respectively. Deaths are recorded as zero in both groups. No serious adverse-event terms are listed.

These are counts for the safety populations defined in the registry record. The safety group sizes do not match all of the other population figures in the record, and no explanation is given for that difference. The entries describe what is recorded for these groups; they are not an estimate of the probability of future events and do not establish that the risk is absent. In general, observing no events in a study still leaves uncertainty about events that could occur but were not observed.

The record does not provide event narratives, severity grading beyond the serious-versus-other categories, exposure-adjusted rates, or further details about safety monitoring. It also does not explain whether events were collected over the intervention period alone or another window. Accordingly, the safety figures should be read narrowly as reported counts and at-risk populations, not as a comprehensive assessment of safety.

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

The registry record documents a randomized, triple-masked pilot study of daily freeze-dried blueberry powder compared with placebo powder. For the primary outcome, it reports negative mean CESD-R changes in both arms between baseline and 12 weeks. Since higher scale scores indicate more severe symptoms, the arm summaries describe average score decreases among the participants included in each summary. The record does not report an estimable formal comparison, so these summaries do not determine whether the observed changes differed between arms.

Nor do the results establish the cause of a change within either arm. In a trial, the main comparative question is whether outcomes differ by randomized assignment, interpreted with uncertainty and the analysis method in view. The registry does not post a comparative estimate, confidence interval, p-value, or statistical analysis for this endpoint. It therefore does not support a claim that the powders caused the observed changes or that the arms had equivalent outcomes.

The pilot designation and the outcome summaries can help readers understand the scope of the record: it contains arm-level descriptive data, but not the inferential results needed to assess the primary comparison. No protocol-based sample-size justification or statistical analysis plan is reported. The sample-size planning illustration is explicitly based on the observed effect and stated assumptions, and should be understood as a planning exercise rather than as a finding about the trial’s power.

The record also lists microbial abundance and fecal short chain fatty acids as secondary outcomes, but does not post analyses for them. The safety entries report no serious or other adverse events and no deaths in the listed groups; those counts are limited to the recorded populations and do not prove absence of risk. The enrollment and population figures are not fully reconciled in the record, and missing-data and analysis-population methods are not described. These limits prevent a complete assessment of the evidence from the registry results alone.

14. Why This Trial Matters Statistically

This study raises several statistical issues that are common in pilot trials. First, a change in each arm is not the same estimand as a contrast between randomized arms. The posted mean changes are useful descriptions, but the comparative question requires an estimate of how outcomes differ by assignment and a measure of its uncertainty. The registry marks that comparison as not estimable and provides no inferential result, making the distinction especially important.

Second, precision and variability are different. The standard deviations describe spread in the observed changes, while a confidence interval would communicate uncertainty in an estimated mean or contrast. Neither can be substituted for the other. Because the record provides no confidence interval for the primary comparison, readers cannot assess the plausible range of comparative effects from the posted summaries.

Third, population definitions and missingness affect interpretation. Enrollment, arm-level outcome counts, and safety populations do not align transparently in the record. The analysis population and missing-data procedures are not reported. Even a clearly randomized design cannot resolve uncertainty about which measurements contributed to an outcome summary when those details are absent.

Finally, planning illustrations based on an observed pilot effect need careful interpretation. They can explore the implications of chosen assumptions, but they are not observed power and do not document why the trial was originally sized as it was. The record’s stated planning assumptions are useful context, yet they do not replace the missing analysis or sample-size rationale. These distinctions help keep descriptive findings, uncertainty, and design planning separate.

15. 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.

Several limitations are specific to the information in this registry record. Enrollment is listed as 20, while the brief summary refers to “40older, sedentary adults.” The record does not explain this inconsistency. The primary-outcome arm summaries report 10 participants for the blueberry arm and 8 for placebo, while the safety entries use at-risk populations of 10 and 9. The record does not reconcile these figures or describe how the populations were defined.

The primary endpoint is described as change in CESD-R score between baseline and 12 weeks, but the record provides only arm-level means and standard deviations. It does not provide baseline or follow-up distributions, individual-level data, or a formal comparison estimate. It also does not report confidence intervals or p-values for the primary endpoint. No statistical model, adjustment strategy, or analysis population is described.

The registry does not report how missing outcome data were handled, whether the recorded summaries include all randomized participants with available measurements, or whether any participants were excluded from analysis. It gives no adherence results or details about protocol deviations. The secondary outcomes are identified, but their analyses and results are not posted. A multiplicity plan is not reported.

Finally, the study is identified as a pilot, but the record does not report the original sample-size justification or a detailed statistical analysis plan. Masking is described as triple without specifying the roles masked. These gaps do not invalidate the reported descriptive summaries, but they constrain their interpretation and prevent a fuller assessment of the trial’s comparative evidence.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Berries, Bugs, and the Blues — NCT05817383.
• Registry record last updated 2025-08-22; status last verified 2025-08.
• Results first posted 2025-08-22.
• 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.

19. Record Summary

The registry lists a completed, randomized, triple-masked, parallel pilot study sponsored by Hebrew SeniorLife. It compares daily freeze-dried blueberry powder with a nutritionally matched placebo powder over 12 weeks in older adults with depressive symptoms. Enrollment is listed as 20, although the brief summary refers to “40older, sedentary adults”; the record does not explain the discrepancy.

The primary endpoint is mean change in CESD-R score from baseline to 12 weeks. The reported mean changes are -5.0 with standard deviation 3.0 for the blueberry arm and -4.0 with standard deviation 4.0 for placebo. A formal two-arm comparison is not estimable in the record, and no inferential analysis is posted. Secondary outcomes concern microbe abundance and fecal short chain fatty acids, but their analyses are not reported. Safety entries list no serious or other adverse events and no deaths in the reported groups. Missing-data methods, analysis populations, and a detailed statistical plan are not reported in the registry record.