Effects of Atomoxetine on Brain Activation During Attention & Reading Tasks in Participants With ADHD & Comorbid Dyslexia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Atomoxetine on Brain Activation During Attention & Reading Tasks in Participants With ADHD & Comorbid Dyslexia (NCT00716274), a randomized phase 4 study. The primary outcome is Change From Baseline to Endpoint in Functional Magnetic Resonance Imaging (fMRI) Activation in Participants With Dyslexia Alone (Pseudoword Rhyming and Semantic-category).

2. Clinical Question

The clinical question is therefore about a measured brain response during task performance, rather than a direct comparison of reading ability or ADHD symptoms as the primary endpoint. The registry lists additional reading, phonological-processing, and ADHD symptom outcomes as secondary measures. Those outcomes cover participants in different diagnostic groups, so each outcome's relevant population matters when interpreting any result.

The record identifies a placebo-controlled randomized study, but it does not report a numerical estimate for the primary outcome or a statistical comparison. It is not possible from the registry record to determine the direction, size, or precision of any change in brain activation, or whether the active and placebo groups differed. The study question can be described from the design and endpoint definition; its answer cannot be inferred in the absence of reported outcome estimates.

3. Trial Design

This was a Phase 4, randomized, double-blind, parallel-group study listed as completed. The registry reports an enrollment of 110. Its stated purpose was to evaluate atomoxetine's effects on brain activation during attention and reading tasks, using functional magnetic resonance imaging in participants with ADHD and comorbid dyslexia. The listed interventions were atomoxetine and placebo.

The atomoxetine arm description specifies oral dosing once daily in the morning for 16 weeks during study period II, at 1.0 to 1.4 mg/kg/day. Participants who completed that period were to be re-randomized for a further 16-week study period III to assess maintenance of benefit after discontinuation. The registry excerpt does not provide the full details of the later-period treatment assignments or explain how those later observations relate to the primary comparison. The placebo description states that it was packaged in the same way as the active comparator to support blinding.

A parallel-group design generally assigns participants to treatment groups that are followed concurrently. Randomization is intended to reduce systematic differences between groups at baseline, while blinding can reduce the influence of treatment knowledge on participant behavior, care, and outcome assessment. These are general design purposes; the registry does not report how randomization was implemented, who was blinded, or whether blinding was assessed.

The primary endpoint is described for participants with dyslexia alone who received study drug and had fMRI data. The study also lists secondary outcomes for participants with dyslexia alone, ADHD alone, and ADHD with dyslexia. The registry gives a start date of 2008-09, a primary completion date of 2016-07, and completed status. It does not report the protocol's planned sample-size justification, allocation ratio, detailed analysis plan, or handling of the study's later re-randomization in the primary analysis.

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: Participants were randomized to either atomoxetine or placebo during study period II. Placebo participants were then assigned to atomoxetine in study period III. Atomoxetine participants were re-randomized to atomoxetine or placebo in study period III. Participants assigned to the healthy control group did not receive any study drug.

Study Period II (16-Weeks)

Reasons for not completing this period:

Study Period III (16-Weeks)

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All participants who received study drug, had Dyslexia Alone and had fMRI data.

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 Change From Baseline to Endpoint in Functional Magnetic Resonance Imaging (fMRI) Activation in Participants With Dyslexia Alone (Pseudoword Rhyming and Semantic-category), measured over Baseline, 16 Weeks.

The primary outcome concerns change from baseline to endpoint in task-related brain activation measured by functional magnetic resonance imaging. The outcome's stated unit is change-from-baseline BOLD response, where BOLD means blood-oxygen-level-dependent response. The registry specifies a mean and standard deviation as the outcome summary measures, with baseline and 16 weeks as the timeframe. The population is participants who received study drug, had dyslexia alone, and had fMRI data.

In general, task-based fMRI measures changes in the BOLD signal associated with brain activity while a participant performs a specified task. It provides a physiological measure of task-related activation; it is not itself a direct measure of reading performance, everyday functioning, or symptom improvement. The registry describes a study examining attention and reading tasks, and the primary outcome title names pseudoword rhyming and semantic-category tasks. However, the accompanying endpoint description refers to a biological motion recognition task. This difference in task descriptions makes it difficult to identify exactly which task-related activation is represented by the primary endpoint. The record does not clarify the discrepancy.

A mean change can describe the average shift in the measured signal over the stated interval, while a standard deviation describes variability among participants. To compare treatment groups, readers would also need the group estimates and an appropriate measure of uncertainty, such as a confidence interval. No numerical primary outcome estimates or uncertainty measures are reported in the registry record. Thus, the endpoint's intended measurement can be described, but the observed change and its precision cannot be evaluated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary measure as continuous, with a mean and standard deviation, and describes the result as change from baseline. In general, a continuous outcome can take a range of values rather than falling into a small set of categories. A mean summarizes the central location of the observed values, while a standard deviation describes how dispersed individual values are around that mean. These summaries do not by themselves show how precisely a treatment-group difference has been estimated.

What does a confidence interval contribute?

In general, a confidence interval expresses uncertainty around an estimated quantity. For a treatment comparison, it can show a range of values compatible with the observed data and the statistical method used. A narrow interval indicates greater precision than a wide interval, all else being equal. A confidence interval is not reported for the primary endpoint in the registry information, so the precision of any treatment contrast is unknown. Neither a mean nor a standard deviation can be reconstructed without the underlying reported values, and no new estimate should be inferred.

How should change from baseline be understood?

Change from baseline compares a participant's endpoint measurement with that participant's starting measurement. At the group level, the analysis may summarize average changes or compare changes between groups. In general, a between-group comparison of change asks whether the average change differs between the assigned interventions, rather than asking whether one group's average changed in isolation. The registry states the baseline and 16-week timeframe, but does not report the exact statistical model, the treatment contrast, or whether baseline values were incorporated in another way. Those analysis details are not reported in the registry record.

For fMRI, the measured BOLD response is tied to task performance and the selected task contrast. In general, interpreting a task-based brain signal requires a clear account of the task, the relevant signal definition, and the analysis procedure. The primary outcome title identifies pseudoword rhyming and semantic-category tasks, while its description identifies a biological motion recognition task. The registry record does not resolve this discrepancy or provide additional details about image processing, regions of interest, or the definition of the reported activation contrast. It is therefore not possible to assess those methodological choices from the record.

Why does the analysis population matter?

The stated primary population includes participants who received study drug, had dyslexia alone, and had fMRI data. Each condition can affect who is included in the endpoint analysis. In general, restricting an analysis to participants with available data can produce a different comparison from an analysis that retains everyone randomized, particularly if the availability of measurements is related to treatment or outcome. The registry does not report the number with fMRI data by group, reasons for unavailable data, or the approach used to address missing observations. It also does not describe whether participants were analyzed according to their original randomized group.

The registry lists a randomized, double-blind, parallel design. In general, randomization helps balance measured and unmeasured baseline characteristics on average, and blinding aims to limit influences that might arise from knowing the assigned treatment. These design features do not eliminate the need to report the actual analysis, participant flow, and uncertainty. The record does not give details of the randomization procedure, allocation concealment, blinding roles, or checks on whether the blind was maintained.

What does multiplicity mean for many outcomes?

Multiplicity arises when several outcomes, tasks, time points, or comparisons are examined. In general, repeated statistical testing can increase the chance that at least one result appears noteworthy by chance, depending on the analysis strategy. The registry lists 83 outcome measures, and its primary outcome is described as having several categories or time points rather than being reduced to one comparison. The record does not report a multiplicity adjustment, a hierarchy of outcomes, or a prespecified strategy for interpreting multiple tests. It would be inappropriate to assume that an adjustment was or was not used beyond what the registry states.

The registry indicates 0 analyses. That does not establish that no analyses were conducted; it means that the record does not list analyses in the available information. The statistical plan, model specifications, treatment-effect estimates, and uncertainty measures are not reported in the registry record. The sample-size information describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such calculations are planning illustrations, not observed power, and they do not substitute for the trial's own design justification. That justification is not reported in the registry record. No numerical planning result is interpreted.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 83 outcome measures, including the fMRI primary outcome and secondary measures of reading, phonological processing, and ADHD symptoms. The primary endpoint itself refers to multiple task categories or time points, and the record notes that it was not reduced to one comparison. When many outcomes, tasks, or time points are examined, multiplicity is a consideration: in general, repeated testing can increase the chance of obtaining a seemingly notable result by chance. A prespecified hierarchy or adjustment can help guide interpretation, but the registry record does not report whether either was used.

The record identifies the primary population as participants who received study drug, had dyslexia alone, and had fMRI data. It does not report how many participants were eligible for this analysis, how many had usable data at baseline and endpoint, or what happened to participants without measurements. The reasons for missing fMRI or other outcome data, and the methods used to handle missingness, are not reported in the registry record. Without these details, the potential influence of missing data on the reported comparison cannot be evaluated.

The registry reports 0 analyses. It does not specify whether analyses followed original randomized assignment, how the later re-randomization was handled, or which statistical models were used. The planned analysis populations and rules for excluding or retaining participants are not reported in the registry record. These omissions limit assessment of both the primary comparison and the many secondary outcomes; they do not show that a particular method was or was not used.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The serious adverse event counts are reported as 0 among 45 participants at risk in the Atomoxetine group and 0 among 44 at risk in the Placebo group. The later listed groups also report 0 serious adverse events: ATX/ATX had 18 participants at risk, ATX/PLA had 18, and PLA/ATX had 35. These are the counts recorded for the listed groups; the registry does not report a statistical comparison of serious adverse events.

For other, non-serious adverse events, the registry reports 35 affected among 45 at risk for Atomoxetine and 31 among 44 for Placebo. It reports 8 among 18 for ATX/ATX, 8 among 18 for ATX/PLA, and 25 among 35 for PLA/ATX. These figures are descriptive counts. They should not be treated as a causal comparison across groups, particularly because the later group labels reflect different treatment sequences and the record does not explain the analysis period associated with each safety count.

The number of deaths is not reported in the registry record. No serious adverse event terms are listed. The absence of listed terms does not provide details about event types, timing, severity beyond the serious/non-serious classification, or the method used to collect safety information.

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

The study was designed to examine whether atomoxetine was associated with changes in task-related fMRI activation in participants with ADHD and dyslexia, with the primary endpoint defined for a dyslexia-alone subgroup. The registry record describes randomization, double blinding, a placebo comparator, and a stated baseline-to-16-week measurement period. Those details explain the intended comparison and outcome, but they do not establish what the study found.

No numerical primary outcome estimate, between-group contrast, confidence interval, or p-value is reported in the registry information available for this analysis. It is therefore not possible to say whether the groups differed, how large any difference was, or how precisely it was estimated. The listed secondary outcomes likewise do not include numerical results in the record. The counts of reported adverse events are descriptive and do not provide a comparative statistical assessment.

Even if an fMRI difference were reported, a change in BOLD response would represent a difference in the measured brain signal during the specified task. In general, that kind of physiological measure is not interchangeable with reading skill, ADHD symptoms, or daily functioning. The registry lists such clinical and educational measures as secondary outcomes, but their results are not reported. The primary task description is also inconsistent: the title names pseudoword rhyming and semantic-category tasks, while the endpoint description names biological motion recognition. This makes the precise construct represented by the endpoint uncertain.

The study's completed status does not itself indicate a favorable, unfavorable, or null result. Nor does the existence of a sample-size planning illustration establish the study's observed power or answer the treatment question. The record supports a cautious account of the design, outcome definitions, and safety counts, but not a claim that atomoxetine changed brain activation or that it did not. A more complete interpretation would require reported estimates, analysis details, and information about participant-level outcome availability.

13. Why This Trial Matters Statistically

This trial raises several statistical issues that are important in studies using brain imaging as an outcome. An fMRI endpoint is a measurement tied to a task and an operational definition of activation. Clear task descriptions are therefore essential: the primary outcome title refers to pseudoword rhyming and semantic-category tasks, while its description refers to biological motion recognition. That inconsistency makes it harder to understand what biological or cognitive process the endpoint is intended to capture.

The study also spans diagnostic groups and multiple types of outcomes. The primary measure is defined in participants with dyslexia alone, while secondary outcomes cover dyslexia alone, ADHD alone, and ADHD with dyslexia. Reading, phonological processing, ADHD symptoms, and brain activation answer related but distinct questions. Their results should be interpreted in the context of their own populations, measurements, and analysis plans. With 83 outcome measures listed, transparent reporting of the primary comparison and any strategy for handling multiple outcomes is especially relevant. The registry record does not report such a strategy.

Another important issue is the distinction between an endpoint definition and an endpoint result. The registry describes a continuous mean change in BOLD response but does not provide a numerical estimate or uncertainty interval. Without those values, readers cannot judge the size or precision of a treatment contrast. A completed trial record can still leave its central statistical question unanswered when outcome estimates and analysis details are absent.

The study's later re-randomization introduces a further design feature that requires clear reporting. The registry states that participants completing study period II were to be re-randomized for study period III to assess maintenance after discontinuation. The record does not explain how those later observations were incorporated into the primary comparison. This highlights why participant flow, treatment sequence, endpoint timing, and analysis population should be reported alongside outcome estimates.

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 principal limitation for interpreting this study is the absence of numerical results for the primary endpoint. The registry record does not report group-specific mean changes, a between-group estimate, or a measure of uncertainty. It is therefore not possible to evaluate the size, direction, or precision of the primary comparison. Numerical results for the listed secondary outcomes are also not reported in the information available for this analysis.

The primary endpoint's task definition is not consistent across its title and description. The title refers to pseudoword rhyming and semantic-category tasks, while the description refers to biological motion recognition. The record does not explain whether these refer to separate measures, a correction, or a different endpoint. Further fMRI details, including image-processing methods and the definition of activation, are not reported in the registry record.

The endpoint population is restricted to participants with dyslexia alone who received study drug and had fMRI data. The number with usable data, the reasons for missing data, and the methods used to address missingness are not reported. The record also does not provide participant flow by randomized arm or make clear how the primary analysis related to original assignment and the later re-randomization. The statistical model, handling of repeated measures, and prespecified multiplicity approach are not reported in the registry record.

The registry lists 83 outcome measures and 0 analyses, but does not provide the analysis plan or estimates needed to interpret those outcomes. The sample-size illustration is described as planning based on an observed effect; it is not a record of observed power or a substitute for the trial's own sample-size justification, which is not reported in the registry record. Safety counts are available, but the record does not report comparative tests, death counts, or serious event terms. These reporting limits prevent a full assessment of efficacy, precision, missing-data sensitivity, and comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effects of Atomoxetine on Brain Activation During Attention & Reading Tasks in Participants With ADHD & Comorbid Dyslexia — NCT00716274.
• Registry record last updated 2022-11-04; status last verified 2022-10.
• Results first posted 2018-02-07.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT00716274 is a completed Phase 4 randomized, double-blind, parallel-group study of atomoxetine and placebo. The registry reports enrollment of 110 and describes a study of participants ages 10 to 16 years old with ADHD and comorbid dyslexia. Atomoxetine was described as once-daily oral treatment for 16 weeks, followed by planned re-randomization for a further 16-week period among participants completing the earlier period.

The primary outcome concerns change from baseline to endpoint in fMRI BOLD response among participants with dyslexia alone who received study drug and had fMRI data. Its title and description identify different task contexts. The registry lists 83 outcome measures and 0 analyses. It does not report numerical primary or secondary outcome estimates, confidence intervals, or p-values in the information available for this analysis.

Serious adverse event counts are reported as 0 in each listed group; other adverse event counts are also recorded. Death counts are not reported in the registry record. These details support a description of the study's design and reporting, but not a conclusion about the primary treatment effect or comparative safety.