An fMRI Study of Self-regulation in Adolescents With Bulimia Nervosa: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for An fMRI Study of Self-regulation in Adolescents With Bulimia Nervosa (NCT00345943), a registered phase not stated study. The primary outcome is Magnetic Resonance Imaging Scans.

2. Clinical Question

The study aims to investigate how changes in frontostriatal neural systems may contribute to the development and persistence of bulimia nervosa. Its stated approach combines multimodal MRI with behavioral measures. The named secondary measures are the Conners Continuous Performance Test-II, Stroop Word-Color Interference, and Weather Prediction Task.

This is a question about measured brain structure and behavioral performance across the listed groups, not a randomized test of treatment. The record does not report a prespecified causal contrast, a treatment assignment, or results establishing that group differences are attributable to bulimia nervosa. It also does not report numerical estimates for the baseline MRI measure or the named secondary measures.

3. Trial Design

The registry describes a completed study sponsored by the New York State Psychiatric Institute. Its listed start was 2004-10 and its primary completion was 2016-09. Enrollment is listed as 71. The study concerns eating disorders and includes adolescents with bulimia nervosa or subclinical bulimia nervosa and healthy control adolescents.

The arms are groups defined by participant status, rather than randomized treatment assignments. Allocation is not stated. The registry record therefore does not establish that the groups are comparable on factors other than their group designation. A difference between groups, if reported, would be an association in this study and would not by itself show that the condition caused the difference.

MRI is listed as an intervention of type “OTHER,” and neuropsychological testing is listed as “BEHAVIORAL.” In context, these are study procedures and assessments, not treatments being compared. The primary measure is MRI-based cortical thickness at baseline. The secondary measures named in the registry are the Conners Continuous Performance Test-II (CPT-II), Stroop Word-Color Interference, and Weather Prediction Task.

The registry lists four outcome measures and two analyses. It does not report the detailed analysis plan, how participants were selected for each analysis, or whether the analyses were adjusted for differences between groups. The exact eligibility criteria, recruitment approach, and handling of participants who did not complete assessments are not reported in the registry record. The completed status indicates the study's registry status; it does not supply numerical findings for the outcomes.

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 Magnetic Resonance Imaging Scans, measured over Baseline.

The primary outcome is magnetic resonance imaging scans, with cortical thickness in neural circuit regions involved in bulimia nervosa described as the target of assessment. The measure is expressed in millimeters, summarized as a mean with standard deviation, and assessed at baseline. The registry's description frames the MRI assessment as a way to examine the structure of regions relevant to the study's focus on frontostriatal neural systems.

As a continuous measure, cortical thickness can be represented by a mean, which describes the central value in a group, and a standard deviation, which describes the spread of individual measurements around that mean. These summaries can help characterize the distributions in the study groups. A mean difference, if estimated, would describe the separation in average measurements; uncertainty around that estimate would be important for judging precision.

The registry record does not report the actual group means, standard deviations, an estimated contrast, a confidence interval, or a p-value for this endpoint. It also does not identify specific cortical regions, explain how MRI measurements were processed, or state whether the primary comparison was adjusted. Accordingly, the stated outcome defines what the study intended to measure, but the numerical magnitude and precision of any group difference are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary measure as continuous: MRI-assessed cortical thickness, expressed in millimeters and summarized by a mean and standard deviation at baseline. It does not report the statistical procedures used to analyze this measure. The concepts below are general explanations of how continuous outcomes and group comparisons are commonly interpreted, not claims about the study's unreported methods.

What does a mean describe?

A mean is a measure of the central tendency of a set of observations. For a continuous measurement such as cortical thickness, it provides a group-level summary in the stated unit. The standard deviation describes how dispersed individual measurements are around the mean. It is not the same as the uncertainty in the estimated mean: uncertainty also depends on the amount of information available and on the analysis approach. The registry specifies mean and standard deviation as the outcome's summary format, but it does not report their observed values.

How would a group contrast be read?

A comparison of group means would describe the observed difference in average measurements between adolescents with bulimia nervosa or subclinical bulimia nervosa and healthy control adolescents. The contrast's direction depends on which group is subtracted from which, so the analysis definition matters. A confidence interval would help show how precisely the contrast was estimated. A narrow interval indicates greater precision than a wide interval, conditional on the model and assumptions used. The registry record does not report a contrast, confidence interval, or direction convention for a contrast.

What does a p-value address?

In general, a p-value measures how unusual results at least as incompatible with a null hypothesis would be under that hypothesis and the specified statistical model. It does not measure the probability that the null hypothesis is true, the size of an effect, or its practical importance. A small p-value alone would not remove concerns about confounding, measurement choices, missing observations, or multiple testing. No p-value for the MRI outcome is reported in the registry record.

Why does the group structure matter?

The registry lists status-based groups and does not state allocation. This is not a randomized treatment comparison. In general, nonrandomized groups can differ in characteristics that are related to both group membership and the outcome. An unadjusted contrast would describe the observed groups but could not separate the condition's association from those other differences. The record does not report whether adjusted analyses were conducted, what covariates might have been considered, or how any adjusted estimate should be interpreted.

What can planning calculations say?

The registry describes a planning illustration based on the observed effect, rather than the study's own design. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such calculations can illustrate the participants per arm associated with a planning scenario under its assumptions. They are not a record of the study's original sample-size justification, and they are not observed power. The registry record does not report the study's own sample-size justification. The numerical illustration values are not reported in the registry information used for this account.

In general, power is a design quantity describing the chance that a specified analysis will detect a specified effect under assumed conditions. It is not a measure of whether a completed study found a real effect. A planning calculation based on an observed effect is especially dependent on that estimate, and its interpretation should remain distinct from the actual analysis and findings. No conclusion about the precision of the study's MRI comparison can be drawn from the planning assumptions alone.

What is not specified?

The registry lists two analyses but does not describe their statistical models, outcome-specific sample sizes, treatment of repeated or correlated measurements, or approach to outliers. It also does not state whether assumptions such as an appropriate distribution for the mean-based analysis were checked. These details matter because a statistical estimate depends not only on the measured values but also on the model and the way observations are handled. They are not reported in the registry record, so they should not be inferred from the outcome's summary format or from the listed planning assumptions.

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("Adolescents With Bulimia Nervosa or Subclinical BN", "Healthy Control Adolescents")
n   <- c(33, 28)
m   <- c(2.98, 2.96)
sp  <- c(0.22, 0.22)
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  Adolescents With Bulimia Nervosa or Subclinical BN  33  2.980  0.220  2.902  3.058
CARM  Healthy Control Adolescents  28  2.960  0.220  2.875  3.045

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary MRI outcome and three named secondary measures: the Conners Continuous Performance Test-II (CPT-II), Stroop Word-Color Interference, and Weather Prediction Task. It also lists four outcome measures and two analyses. Examining multiple outcomes can create a multiplicity issue: when many statistical questions are tested, the chance of at least one apparently unusual result can increase, depending on how tests are related and what decision rule is used. This is a general statistical concern, not a statement that any particular adjustment was or was not applied in the study.

The registry record does not report whether the analyses controlled for multiplicity, how the primary and secondary outcomes were prioritized in the analysis, or how the two listed analyses relate to the outcomes. It does not provide enough detail to reconstruct the set of statistical tests or determine an adjustment strategy. A reader should not assume that either a correction or no correction was used.

Missing-data handling and analysis populations are also not reported in the registry record. The registry does not state how many participants contributed measurements to each endpoint, whether any MRI or behavioral assessments were incomplete, or whether exclusions occurred. In general, missing observations can affect both the precision and the interpretation of estimates, particularly if the likelihood of a missing measure relates to participant characteristics or outcomes. Without the analysis counts and missingness methods, the extent of this issue cannot be evaluated.

The registry's enrollment figure is not, by itself, an outcome-specific analysis denominator. Nor does the record identify an intention-to-treat or per-protocol population, which are terms more commonly used for randomized treatment studies. The groups are not described as randomized arms, and the relevant analysis-population definitions are not reported in the registry record.

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 lists serious adverse event figures separately for adolescents with bulimia nervosa or subclinical bulimia nervosa and healthy control adolescents. For the first group, the serious-event denominator at risk is 38 and the number affected is 0; for healthy control adolescents, the denominator at risk is 33 and the number affected is 0. The listed deaths are 0 in both groups. The registry also reports 0 affected for other adverse events in each group, with denominators at risk of 38 and 33, respectively. No serious-event terms are listed.

These are registry safety-reporting counts, not an estimate of comparative risk. The record does not define the observation period for these figures, describe how events were collected, or explain whether the counts cover every participant or only those included in the safety reporting. Zero affected in the listed categories means that no events were counted in those entries; it does not establish that no unrecorded or unreported events occurred. Because the study groups are not randomized treatment arms, these figures should not be read as a safety comparison between treatments. The registry record does not report a treatment safety analysis.

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

The study is designed to examine MRI and behavioral measures in adolescents with bulimia nervosa or subclinical bulimia nervosa and healthy control adolescents. Its primary MRI measure is baseline cortical thickness in neural circuit regions described as involved in bulimia nervosa. The stated aim connects the investigation to frontostriatal neural systems and the development and persistence of the condition.

What the registry information does not establish is whether the groups differed on cortical thickness or any behavioral measure. Numerical outcome results, estimates of group differences, and uncertainty measures are not reported in the registry record. Consequently, it is not possible to determine the direction, magnitude, or precision of any outcome comparison from the available record.

Even if a group difference were reported, this design would not by itself establish that bulimia nervosa caused a structural or behavioral difference. Allocation is not stated, and the groups are not a like-for-like control comparison. General interpretation of nonrandomized group comparisons must consider other characteristics that may differ between groups and may also relate to measured outcomes. The registry does not report whether such factors were assessed or adjusted for.

The study's completed status and its enrollment listing are descriptive registry entries, not substitutes for outcome estimates. Similarly, the listed zero adverse-event counts do not answer the primary research question. The record supports an account of the study's purpose, groups, and planned measurements, while the numerical findings needed to evaluate the primary or secondary outcomes are not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates how a clinical registry can describe a research question that is not a conventional treatment comparison. The groups are adolescents with bulimia nervosa or subclinical bulimia nervosa and healthy control adolescents; MRI and neuropsychological testing are listed as study procedures. Recognizing this structure matters because an association between group membership and a measurement should not be interpreted as the effect of an assigned intervention.

The primary outcome is a continuous structural measure, with cortical thickness expressed in millimeters and described using a mean and standard deviation. That format points to questions about central tendency and variability, but it does not by itself provide an estimate of how groups compare. The absence of numerical results in the registry record makes clear why a measure's definition and a study's findings are different kinds of information.

The record also names several behavioral outcomes. Multiple measures can broaden the scientific questions explored, while making it important to understand which outcomes were primary, how analyses were organized, and whether multiplicity was addressed. Those analysis details are not reported in the registry record. This limits the ability to interpret any selection among possible findings, even if numerical results were available elsewhere.

Finally, the registry's planning assumptions should be distinguished from an original design justification or observed power. A planning illustration based on an observed effect is a scenario for future planning, not evidence that the completed study had a particular probability of detecting an effect. These distinctions—measurement versus result, association versus causation, and planning versus observed performance—are central to careful statistical reading of this record.

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.

The registry record leaves several important limitations and interpretive details unresolved. It does not report the numerical primary MRI results or the secondary behavioral results, so the outcome patterns, estimated group contrasts, and their precision cannot be evaluated. It also does not report the specific brain regions assessed beyond the broad description of neural circuit regions involved in bulimia nervosa, or the MRI acquisition and processing methods.

The study groups are defined by bulimia nervosa or subclinical bulimia nervosa status and healthy control status. Allocation is not stated, and the record notes that the arms are not a like-for-like control comparison. The registry does not report group characteristics, potential confounders, or adjusted analyses. Any difference between groups would therefore need cautious interpretation, with no causal conclusion supported by the design description alone.

Other unreported details include eligibility criteria, recruitment procedures, outcome-specific analysis counts, missing-data handling, analysis populations, and the statistical models used. The registry lists four outcomes and two analyses but does not explain the relationship between them or report a multiplicity strategy. It also does not give the study's own sample-size justification. These omissions limit assessment of precision, selection, analysis choices, and reproducibility.

The safety entries show zero affected for the listed serious and other adverse event categories, but the record does not explain ascertainment methods or observation periods. Thus, the entries should be read as reported counts rather than as a complete characterization of safety. Overall, the registry description is informative about the study's aims and measures, but insufficient for a full evaluation of its outcome findings or analytical validity.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: An fMRI Study of Self-regulation in Adolescents With Bulimia Nervosa — NCT00345943.
• Registry record last updated 2021-12-02; status last verified 2021-12.
• Results first posted 2021-12-02.
• 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

NCT00345943, “An fMRI Study of Self-regulation in Adolescents With Bulimia Nervosa,” is listed as completed and sponsored by the New York State Psychiatric Institute. The study concerns eating disorders, lists enrollment of 71, started in 2004-10, and has primary completion listed as 2016-09.

The registry describes adolescents with bulimia nervosa or subclinical bulimia nervosa and healthy control adolescents. MRI and neuropsychological testing are listed. The primary outcome is baseline MRI assessment of cortical thickness, expressed in millimeters and summarized by mean and standard deviation. Secondary measures include the Conners Continuous Performance Test-II, Stroop Word-Color Interference, and Weather Prediction Task.

Numerical outcome findings and detailed analysis methods are not reported in the registry record. The listed groups are not a like-for-like control comparison, and allocation is not stated.