Hippocampal Network Changes Following Mindfulness Training in Tobacco Vaping Adolescents in an Open-label, Pilot Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hippocampal Network Changes Following Mindfulness Training in Tobacco Vaping Adolescents in an Open-label, Pilot Study (NCT06503159), a non-randomized na study. The primary outcome is Change in Brain Connectivity Network.

2. Clinical Question

3. Trial Design

NCT06503159 was an open-label, non-randomized pilot study with a parallel structure. The registry lists the phase as NA and the planned enrollment as 14. The sponsor was the National Institute on Drug Abuse (NIDA). The study started on 2025-05-07, had a primary completion date of 2025-09-11, and is listed as terminated.

The design description includes two baseline groups. Adolescents ages 13-18 years old with a history of nicotine vaping and vaping 4-7 days per week were to complete structural and resting fMRI and questionnaires. Adolescents ages 13-18 years old with no history of nicotine vaping were also to complete structural and resting fMRI and questionnaires. Vapers from the baseline assessment group were then intended to undertake MBSR training, with a post-intervention assessment and second fMRI scan.

The MBSR program was described as a 9-week intervention, once per week, in person or remotely. The study also lists fMRI as an intervention of type “Other”; the registry description presents brain imaging as part of assessment rather than as a treatment. Masking was listed as none. The design was therefore open label, and allocation was not randomized.

The registry record states that participants were not recruited to the interventional phase because of study termination. That fact is central to interpreting the design: the planned pre- and post-training measurements were not obtained for an intervention cohort, and no intervention outcome analysis is reported. The baseline groups do not serve as a randomized, like-for-like treatment comparison.

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: Of the 14 participants consented, one participant was screen failure and one participant did not start due to study termination

Baseline Period

Interventional Study

Analysis population for the primary outcome, as defined in the registry: Modified Intention-to-Treat Analysis Dataset. Analysis applies to participants in the MBSR Training group. Participants were not recruited to the interventional phase (MBSR training) due to study termination.

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 in Brain Connectivity Network, measured over Baseline (pre MBSR training) and post-MBSR training (1-6 weeks after MBSR training).

The primary endpoint was titled “Change in Brain Connectivity Network.” It was defined as the change from the baseline fMRI scan, before MBSR, to the post-MBSR scan. The description specifies the direction of change as post-pre and places the post-training scan 1-6 weeks after MBSR training.

Resting-state functional connectivity (rsFC) is generally used to characterize statistical relationships among brain signals measured while a participant is at rest. In general, examining connectivity networks can describe patterns of coordination between brain areas, rather than a single behavioral measure. The stated rationale was to examine vaping-related rsFC alterations in hippocampal networks and whether changes in those networks were associated with reductions in tobacco vaping behavior.

The registry record does not specify a unit, a summary parameter, or a measure of dispersion for this endpoint. It also states that the analysis population was a modified intention-to-treat dataset of participants in the MBSR training group, while noting that participants were not recruited to the intervention phase. Consequently, the record defines the intended measurement but contains no observed pre/post endpoint result or estimate of change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods information distinguishes what the study planned to measure from what was actually analyzed. The primary outcome was a pre/post change in brain connectivity for participants in the MBSR training group. The registry specifies change as post-pre and identifies a post-training fMRI window of 1-6 weeks after training. However, it also states that participants were not recruited to the intervention phase because the study was terminated. No primary analysis is reported.

What does a pre/post change represent?

In general, a pre/post change compares a participant’s measurement after an intervention with their measurement before it. The within-person structure can account for characteristics that remain stable across the two measurements, but it does not by itself rule out changes over time unrelated to the intervention. Interpretation also depends on the quality and consistency of measurements, the timing of follow-up, and the analysis population. In this study, the intended contrast is clear, but the registry record does not report collected post-training measures or a calculated change.

The primary outcome description gives no unit, summary parameter, or dispersion measure. The registry record does not report the specific connectivity metric, the brain-network calculation, preprocessing choices, covariates, or a statistical model. These details are relevant because fMRI connectivity can be summarized in different ways, and analytic choices can affect the resulting estimates. No particular method should be inferred from the endpoint title alone.

Why does the non-randomized design matter?

In general, random allocation is used to make groups comparable, on average, with respect to characteristics that may influence outcomes. Here, participants were classified into baseline groups according to vaping history, and the allocation is listed as non-randomized. The non-vaping group therefore is not a randomized control group for the MBSR intervention. Differences between baseline groups, if analyzed, would be descriptive or observational unless additional design and analytic features supported stronger conclusions. The registry record does not report a completed group-comparison analysis.

The record describes the study as open label, with no masking. In general, awareness of group or intervention status can influence self-reported outcomes, participation, or assessment. The record lists self-reported vaping behavior and engagement outcomes, but it does not report their results or specify safeguards against measurement bias.

What do the planning illustrations mean?

Any sample-size figures associated with the posted planning material are illustrations, not observed power. The stated assumptions are 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 stated fraction of the observed effect. The assumptions also distinguish total events for time-to-event calculations from participants per arm for other calculations. These planning conventions do not describe the study’s own design or establish that the trial had a particular probability of detecting an effect. The registry record does not report the trial’s sample-size justification, and no planned intervention cohort was recruited.

In general, power calculations depend on assumptions about the effect size, variability, allocation, and analysis. A calculation based on an observed effect is especially sensitive to the estimate used as its starting point. It should be treated as a planning illustration, not as evidence that a result was detected or that a negative result would be informative. No numeric planning result or observed effect estimate is reported in the registry record.

How should uncertainty be understood?

A confidence interval is generally a range of values compatible with an estimate under the assumptions of a statistical model. Its width reflects statistical precision, while its interpretation also depends on the design, measurement, and model. No confidence interval is reported for the primary outcome because no primary endpoint estimate is reported. There is therefore no basis in the registry record for describing the magnitude or precision of brain connectivity change.

In general, over-dispersion occurs when observed variation is greater than a model assumes. It can make standard errors too small if the model does not account for the extra variation. The registry record does not identify a count model, variance structure, or over-dispersion assessment; accordingly, no claim about its handling is warranted. More broadly, the record does not report a detailed statistical analysis plan, interim analyses, missing-data method, or model specification. Those omissions prevent a fuller assessment of how a completed analysis would have handled uncertainty and design features.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and zero analyses. The primary endpoint concerns change in brain connectivity network. Secondary outcomes are participant self-report of change in vaping behaviors, engagement with MBSR training, and engagement with the Craving-to-Quit app. The outcomes represent different measurements and questions, but the registry record does not report results for any of them.

When a study evaluates multiple outcomes or multiple statistical tests, the chance of at least one apparently unusual result can increase. General approaches to multiplicity include prespecifying a primary outcome, adjusting tests, or interpreting secondary analyses as exploratory. The registry record does not report whether a multiplicity strategy was planned, whether outcomes were prioritized beyond the primary designation, or how multiple analyses would have been handled. No adjustment method should be inferred.

The primary analysis population is described as a modified intention-to-treat dataset for participants in the MBSR Training group. The same description states that participants were not recruited to the intervention phase due to termination. No intervention analysis population or outcome data are therefore reported. The record does not explain how the modified intention-to-treat population was defined, whether any participants contributed partial measurements, or how exclusions were to be handled.

Missing-data procedures are not reported in the registry record. In general, missingness can affect estimates when the availability of measurements is related to participant characteristics or outcomes. Common analytic approaches rely on assumptions about why measurements are missing, and those assumptions should be made explicit. The registry does not identify an imputation method, complete-case approach, sensitivity analysis, or follow-up procedure for missing outcomes. Given the stated non-recruitment to the intervention phase, this is not simply a matter of occasional missing post-training scans: the intended intervention endpoint was not analyzed.

11. 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 and other adverse-event counts for two baseline groups. For the Baseline Group: Non-vapers, 11 participants were listed as at risk for serious events and 11 for other events; the corresponding affected counts were zero. For the Baseline Group: Vapers, 1 participant was listed as at risk for serious events and 1 for other events; the corresponding affected counts were zero. Deaths were listed as zero in both groups.

These figures describe the groups and event counts entered in the registry; they are not evidence that no adverse events could occur. The record does not report adverse-event observations for an MBSR intervention group. It states that participants were not recruited to the interventional phase, so the baseline figures cannot characterize safety during the planned 9-week training.

In general, a zero count among a limited number of participants does not establish absence of risk. The amount of information depends on the number of people observed, their exposure, the event definitions, and the length and completeness of follow-up. The registry record does not provide additional detail about event ascertainment or follow-up for these counts.

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

The record documents a study designed to examine hippocampal-network connectivity in adolescents who vape and to assess a mindfulness-based training program. Its planned primary measure was change in brain connectivity from before to after MBSR. The record also lists self-reported vaping behavior and engagement outcomes, along with an aim to assess accessibility and feasibility.

What the record does not provide is an intervention result. It reports that the study was terminated and that participants were not recruited to the intervention phase. There is no reported primary endpoint estimate, no result showing a direction or magnitude of connectivity change, and no statistical uncertainty for such a change. The listed outcomes and study aims should not be treated as findings.

The study’s non-randomized, open-label design also limits what a hypothetical group contrast could establish. Baseline vapers and non-vapers were not assigned at random, and the non-vaping group was not a randomized control for MBSR. General differences between these groups would not, on their own, show that vaping caused a connectivity difference. Likewise, without a completed intervention cohort and suitable outcome data, the record cannot establish whether MBSR changed connectivity or vaping behavior.

The posted adverse-event counts are limited to the baseline groups. They include no events among the participants listed as at risk, but they do not provide an assessment of adverse events during MBSR. Overall, the registry record is informative about the intended questions, population, and planned measurements; it does not contain outcome evidence to answer the intervention question.

13. Why This Trial Matters Statistically

This study illustrates an important distinction in clinical research: a carefully stated research question and a defined outcome do not guarantee that an outcome estimate will be available. The registry identifies a biologically focused primary endpoint, change in brain connectivity network, and connects it with behavioral questions about vaping and mindfulness engagement. Yet the intervention phase did not recruit participants, so the central pre/post contrast was not analyzed.

That distinction matters for statistical interpretation. The endpoint description establishes what the investigators intended to measure, but it does not establish the size or direction of an effect. Without an estimate and its uncertainty, readers cannot judge whether a potential change would be small or large, or whether the result would be precise. The registry record therefore supports conclusions about the planned design and the absence of a reported intervention result, not conclusions about efficacy or lack of efficacy.

The non-randomized baseline comparison also provides a useful reminder that a comparison group is not necessarily a causal control. The non-vaping group offered a baseline reference for a different population, but it was not randomly assigned to a treatment condition. That distinction is especially important when study aims concern differences in brain measures associated with vaping, because other differences between groups could also matter.

Finally, the study record makes clear why completion status, recruitment, outcomes, and analyses must be read together. The planned sample and training schedule describe the intended investigation; the termination and non-recruitment statements define what was actually available for analysis. This is a case where the most defensible statistical interpretation is bounded: the design and aims are documented, while intervention effects remain unestimated in the registry record.

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 most consequential limitation is that the registry reports termination before recruitment to the MBSR intervention phase. The primary endpoint requires baseline and post-training fMRI measurements in that group, but no corresponding intervention analysis is reported. The stated planned enrollment does not change that limitation and should not be read as the number of participants who completed the intervention.

The design was non-randomized and open label. Baseline vaping and non-vaping groups were defined by participants’ history and behavior, not by randomized allocation. Consequently, a baseline group comparison would not by itself isolate an effect of vaping. Open-label status could also be relevant to self-reported behaviors and engagement, though the record contains no completed outcome analyses to evaluate this.

The registry description does not report a detailed statistical model, the specific connectivity metric, preprocessing choices, adjustment variables, or a method for handling missing data. It does not report a sample-size justification, interim analyses, or a detailed statistical analysis plan. These items are not reported in the registry record, so analytic choices and their consequences cannot be assessed.

The posted safety counts concern baseline groups, not the planned intervention cohort. They therefore offer no direct information about safety during MBSR training. The record also does not report outcome estimates or confidence intervals for the listed primary and secondary measures. These limitations constrain both the questions that can be answered and the precision that can be discussed.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Hippocampal Network Changes Following Mindfulness Training in Tobacco Vaping Adolescents in an Open-label, Pilot Study — NCT06503159.
• Registry record last updated 2026-02-27; status last verified 2026-02.
• Results first posted 2026-02-27.
• 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

NCT06503159, “Hippocampal Network Changes Following Mindfulness Training in Tobacco Vaping Adolescents in an Open-label, Pilot Study,” was a phase NA, non-randomized, open-label pilot study sponsored by the National Institute on Drug Abuse (NIDA). It planned to enroll 14 adolescents and included baseline groups of vapers and non-vapers, with a 9-week MBSR program planned for adolescents who vape.

The primary endpoint was change in brain connectivity network from baseline to post-MBSR fMRI, with the post-training scan scheduled 1-6 weeks after training. The registry lists four outcome measures and zero analyses. It reports that the study was terminated and that participants were not recruited to the interventional phase. Thus, no primary intervention result is reported. Baseline adverse-event counts list zero serious events, zero other events, and zero deaths in each of the two recorded groups.