Effects of Citicoline on Brain Function and Behavior in Marijuana-Dependent Individuals: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Citicoline on Brain Function and Behavior in Marijuana-Dependent Individuals (NCT00158249), a randomized phase 2 study. The primary outcome is Marijuana Use.

2. Clinical Question

The study was designed to examine citicoline in relation to marijuana-use patterns, craving, brain activation, and cognitive functioning. Its summary describes three aims, while also stating that only studies for Aim 1 were completed. The primary outcome posted for this analysis is marijuana use, measured as reported uses per day over 8 weeks of treatment. It is a behavioral measure of use, rather than a direct measure of brain function or a laboratory measure of marijuana metabolism.

The arm summaries report a mean of 2.5 reported uses per day for placebo and 3.9 for citicoline. The associated standard errors are 0.71 and 1.1, respectively. Those descriptive values alone do not establish the size or precision of an arm-to-arm effect. In particular, the registry record says that values were missing or not estimable for a two-arm comparison of this continuous endpoint. It does not post an inferential comparison for the primary outcome.

3. Trial Design

This was a Phase 2, randomized, triple-masked, parallel-group study of citicoline and placebo. The registry record lists Mclean Hospital as the sponsor and gives the overall enrollment as 21. The arm summaries list 9 participants for placebo and 10 for citicoline; the record does not explain how these arm-level outcome counts relate to the overall enrollment figure.

The intervention is described as citicoline at 2 gm/day, and the placebo as matched capsules. The study summary describes an 8-week treatment period. The primary outcome, marijuana use, was measured during those 8 weeks and recorded as reported uses per day. The record lists Neurocognitive Function as a secondary outcome and identifies two outcome measures, though only one secondary outcome is posted in the analysis details.

Randomization means that allocation to study arms was intended to occur by chance. In general, random allocation can help balance prognostic characteristics across arms, although it does not guarantee balance in a small study. Triple masking indicates that the record classifies the study as masked at three levels, but it does not identify which roles were masked or describe the masking procedures. Those details are not reported in the registry record.

The record gives a study start of 2009-09, primary completion of 2013-01, and status of Completed. The summary states that only studies for Aim 1 were completed. Although the aims also mention laboratory responses, pharmacokinetics, cue-induced craving, and EEG, the available result details do not report findings for those measures. It would therefore be inappropriate to treat every planned aim as a completed or analyzed component of this trial.

The record does not report the randomization sequence method, allocation concealment, sites, eligibility criteria, or reasons for discontinuation. It also does not report a protocol-level sample-size justification or a detailed analysis plan. Those omissions limit how fully the design and its conduct can be assessed from the registry record.

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 Marijuana Use, measured over Measured for 8 weeks of treatment.

The primary endpoint is marijuana use, expressed as reported uses per day and summarized as a mean. The record says it was measured for 8 weeks of treatment. This is a continuous outcome: each participant's use is represented numerically, and the arm summaries describe the average reported use in each group.

Use is a direct behavioral measure related to the study's stated aim of measuring marijuana-use patterns in participants' natural settings. The study summary also describes interest in craving, brain activation, and cognitive functioning, but those constructs are not interchangeable with reported use. The primary endpoint captures the reported frequency of use, not the amount consumed, cannabis exposure, or changes in brain activation.

For the placebo arm, the posted mean is 2.5 reported uses per day, with a standard error of 0.71. For the citicoline arm, the mean is 3.9, with a standard error of 1.1. The record does not post an estimable comparison between these means. Thus, the endpoint summaries can be read descriptively, but they do not supply an inferential estimate of the treatment contrast or its uncertainty.

In general, selecting an endpoint aligned with a trial aim helps make the question measurable. A reported-use measure also depends on how use was recorded and on the completeness and accuracy of those reports. The registry record does not describe the reporting instrument, assessment schedule within the 8-week period, or procedures for handling incomplete reports. Those measurement details are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is this?

The primary measure is continuous and summarized by its mean. A mean describes the central level of a numeric outcome across participants in an arm. Here, the outcome is reported marijuana uses per day during 8 weeks of treatment. The posted arm means are 2.5 for placebo and 3.9 for citicoline. These are descriptive summaries and do not, by themselves, show whether the arms differ beyond what could plausibly arise from sampling variation.

The record labels the accompanying spread as standard error. In general, a standard error represents the estimated uncertainty in a summary statistic, such as a mean. It is different from a standard deviation, which describes variation among individual measurements. The posted standard errors are 0.71 for placebo and 1.1 for citicoline. The record does not provide the individual observations or the standard deviations, so the participant-level distribution cannot be characterized from these summaries.

What would an arm comparison usually report?

In general, an analysis comparing two randomized arms for a continuous outcome may report an estimated difference between arm means, together with an uncertainty interval and possibly a test statistic or p-value. The estimate describes the contrast; the interval indicates the precision under the analysis assumptions; and a test statistic or p-value summarizes how compatible the data are with a specified null hypothesis. These quantities answer related but distinct questions. None of those inferential quantities for the primary endpoint is reported in the registry record.

The record specifically marks the two-arm comparison as missing or not estimable for this continuous endpoint, and it lists zero analyses. Therefore, no inferential result should be inferred from the separate means and standard errors. Computing a new contrast or interval from these summaries would require choosing assumptions that are not documented in the registry record. Such a calculation could not substitute for the sponsor's analysis, if one exists elsewhere.

Why does precision matter?

In general, an estimate is more informative when its uncertainty is also reported. A confidence interval can communicate both the direction and the range of effects compatible with the data, given the model and assumptions. A wide interval may leave substantial uncertainty even when an estimate points in one direction. A narrow interval can indicate greater precision, but does not by itself establish that an effect is important. Since no interval for the primary comparison is posted, the precision of the arm-to-arm contrast is not available.

Standard errors also should not be read as ranges containing most individual participants' results. They concern uncertainty in an estimated mean, not the observed variability among participants. The registry record does not provide enough distributional detail to assess skewness, outliers, or whether a different summary might better describe reported use.

How should the design inform interpretation?

In general, randomization is intended to make treatment assignment independent of measured and unmeasured prognostic factors at allocation. It supports a causal interpretation when allocation is implemented as planned, outcome data are appropriately handled, and the analysis preserves the randomized comparison. The registry record identifies the study as randomized, but does not report the sequence generation, allocation concealment, analysis population, or missing-data procedures. These features cannot be evaluated from the registry entries.

The study is listed as triple-masked and parallel-group. In general, masking can reduce the influence of expectations on care, assessment, and reporting, depending on who is masked and how the procedures are carried out. The record does not specify the masked roles or describe how masking was maintained. Therefore, the classification is useful design information, but it does not establish that masking was successful.

What do planning calculations mean?

The registry entries describe sample-size planning illustrations based on the observed effect, with two-sided significance level 0.05, equal allocation, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the trial was designed around those assumptions. They also cannot establish the probability that the posted result is true. No protocol sample-size justification is reported in the registry record, and no numerical planning result is needed to interpret the primary endpoint.

In general, planning calculations depend on assumptions about the effect worth detecting, outcome variability, allocation, significance threshold, and analysis method. If those assumptions differ from the eventual trial conduct or the observed data, the planning illustration may not describe the study's actual operating characteristics. The registry entries do not provide a sample-size justification from the trial's own design, interim-analysis details, or a complete statistical analysis plan.

What statistical information is unavailable?

The record does not report a formal primary comparison, confidence interval, p-value, adjusted analysis, or individual-level outcome data. It also does not explain whether the reported arm summaries include all randomized participants, an observed-case subset, or another analysis population. These gaps prevent a fuller appraisal of precision, robustness, and potential bias. The sound reading is consequently descriptive: the record posts arm means and standard errors, while the designated two-arm comparison is not estimable in the registry record.

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("Placebo", "Citicoline")
n   <- c(9, 10)
m   <- c(2.5, 3.9)
sp  <- c(0.71, 1.1)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
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  Placebo  9  2.500  2.130  0.863  4.137
CARM  Citicoline  10  3.900  3.479  1.412  6.388

11. Multiplicity, Missing Data and Analysis Populations

The study summary describes three aims, and says that only studies for Aim 1 were completed. It lists Neurocognitive Function as a secondary outcome and identifies two outcome measures, while the analysis details indicate one secondary outcome posted and zero analyses. The registry record does not report a multiplicity procedure, such as an adjustment for testing several outcomes or contrasts, nor does it explain a prespecified hierarchy among the aims and outcomes. Without those details, the control of false-positive findings across multiple analyses cannot be assessed.

The record does not report how missing outcome measurements were handled, how much data were missing, why any data were missing, or whether participants discontinued treatment or follow-up. The primary two-arm comparison is flagged as having values missing or not estimable, but this flag does not explain the cause. Missingness can affect an estimate if the observed participants differ systematically from those without measurements. In general, methods for addressing missing data rely on assumptions, and those assumptions should be made explicit; the applicable methods and assumptions are not reported in the registry record.

The record also does not identify an analysis population, such as all randomized participants or participants with observed outcomes. Although overall enrollment is listed as 21, the arm summaries list 9 for placebo and 10 for citicoline. The registry record does not reconcile these figures or say whether the summaries reflect the same population used for any planned analysis. A conclusion about adherence to an intention-to-treat or other analysis principle would therefore be unsupported.

No interim-analysis plan, stopping rule, or detailed statistical analysis plan is reported in the registry record. These omissions limit the ability to determine which analyses were prespecified and how missingness or multiple outcomes were handled.

12. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry record lists serious adverse events for each arm. It reports zero participants affected among 9 at risk in the placebo group and zero among 10 at risk in the citicoline group. The serious-adverse-event terms list is empty. The record therefore does not provide any serious adverse event descriptions for this study in the registry record.

For other adverse events, the record lists one affected participant among 9 at risk in the placebo group and one among 10 at risk in the citicoline group. It does not provide event terms, severity details, timing, or a breakdown by type. These counts describe what is recorded in the adverse-event summary; they do not establish whether an event was caused by study treatment.

Deaths are listed as null for both arms. A null value is not a reported count of zero, so deaths are not reported in the registry record. The safety information is limited to the figures and categories listed; the record does not describe the safety-monitoring methods, event definitions, or duration of safety follow-up.

In general, adverse-event counts need context about how events were defined, collected, and attributed, and about the amount of follow-up. Small arm-level summaries also provide limited information about uncommon events. The listed figures should therefore be read as registry summaries, not as a complete assessment of safety or proof that no unlisted event occurred.

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

The result establishes that the registry record posts descriptive means for reported marijuana uses per day during treatment: 2.5 in the placebo arm and 3.9 in the citicoline arm. It also posts standard errors of 0.71 and 1.1, respectively. Those summaries describe the recorded outcome at arm level. The registry record does not provide an estimable two-arm comparison for this endpoint.

Because no treatment contrast, confidence interval, or formal test is posted, the available outcome details do not quantify the difference between arms or its statistical uncertainty. The arm means should not be treated as proof that citicoline increased or decreased marijuana use. Nor do these registry entries establish that the arms were equivalent. A conclusion of equivalence would require an appropriate design and analysis, including a defined equivalence margin, which are not reported in the registry record.

The outcome is reported use frequency, not a direct measure of craving, cognitive performance, brain activation, marijuana absorption, metabolism, or EEG activity. The study summary describes aims involving those topics, but says only studies for Aim 1 were completed. Detailed results for the other measures are not reported in the registry record. Neurocognitive Function appears as a secondary outcome, but its result is not included in the available outcome details.

The randomized, triple-masked, parallel design gives useful context for how the trial was intended to compare assignments. However, the registry record does not report the analysis population, missing-data handling, masking procedures, or a detailed statistical plan. Those gaps make it difficult to assess how the posted summaries relate to all enrolled participants and how robust a potential comparison would be.

In practical statistical terms, the record supports a limited descriptive reading, not a conclusion about the effect or efficacy of citicoline. It does not provide an estimate precise enough to judge the magnitude of any arm difference, and it does not resolve the study's broader scientific aims. No medical conclusion should be drawn from the descriptive summaries alone.

14. Why This Trial Matters Statistically

This trial is statistically notable because the registry record contains arm-level summaries for a continuous primary outcome but does not contain an estimable comparison between the randomized arms. It illustrates the distinction between reporting group means and reporting a treatment-effect estimate. Readers need the latter, together with its uncertainty, to evaluate the strength and precision of a comparative result.

The study is described as randomized, triple-masked, and parallel-group, which identifies the intended framework for a controlled comparison. Yet design labels do not replace information about implementation and analysis. The registry record does not describe allocation procedures, masking roles, missing-data methods, or the analysis population. These details matter when determining whether an observed comparison can be interpreted as a valid estimate of the assigned treatment contrast.

The primary endpoint also focuses the statistical question. Reported marijuana uses per day is a behavioral measure corresponding to one part of the study's stated aims. The summary includes additional questions about craving, brain activation, cognitive functioning, pharmacokinetics, laboratory responses, and EEG. The record says only Aim 1 studies were completed, underscoring why conclusions should remain tied to outcomes with posted results rather than extend to the full set of scientific aims.

Finally, the incomplete inferential reporting is itself informative for evidence appraisal. Without an effect estimate and uncertainty interval, readers cannot judge how compatible the data are with materially different effects. The arm summaries are not a substitute. This case demonstrates why transparent reporting of analysis methods, missing data, and comparative estimates is essential for understanding what a clinical trial's results can support.

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 main limitation of the available result is that the registry record does not report an estimable two-arm comparison for the continuous primary endpoint. Although arm means and standard errors are posted, no comparative estimate or uncertainty interval is available. This prevents assessment of the magnitude and precision of any treatment contrast.

The registry record does not explain the relationship between overall enrollment of 21 and the arm-level outcome counts of 9 and 10. It does not state whether the arm summaries are based on all randomized participants, participants with complete outcome data, or another population. Missing-data amounts, reasons, and handling are not reported in the registry record. These omissions hinder assessment of selection bias and the representativeness of the outcome summaries.

Measurement details for reported marijuana use are also limited. The record does not describe the reporting instrument, how often measurements were collected, or how repeated observations during the 8-week treatment period were reduced to the reported mean. The endpoint is specifically reported uses per day; it should not be assumed to measure quantity consumed, craving, or biological exposure.

The registry record identifies the study as triple-masked, but does not say which participants or staff were masked, how masking was maintained, or whether masking was assessed. It also does not report the allocation method, eligibility criteria, discontinuations, concomitant treatment, or protocol-level sample-size justification. These details are not reported in the registry record and cannot be inferred from the design labels.

Finally, the summary states that only studies for Aim 1 were completed. Results for the broader laboratory, pharmacokinetic, cue-reactivity, EEG, and cognitive questions are not included in the registry entries. The limited safety summaries likewise lack event terms for other adverse events and do not report deaths as a numeric count. These constraints call for a narrow interpretation of the posted outcome information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Effects of Citicoline on Brain Function and Behavior in Marijuana-Dependent Individuals — NCT00158249.
• Registry record last updated 2014-10-22; status last verified 2014-10.
• Results first posted 2014-10-22.
• 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

NCT00158249 is a completed Phase 2 randomized, triple-masked, parallel-group study sponsored by Mclean Hospital. The registry record lists overall enrollment of 21, a start of 2009-09, and primary completion of 2013-01. The study compared citicoline, described as 2 gm/day, with matched-capsule placebo over an 8-week treatment period.

The posted primary endpoint is mean reported marijuana uses per day. The placebo arm mean is 2.5, with standard error 0.71; the citicoline arm mean is 3.9, with standard error 1.1. The registry record flags the two-arm comparison as not estimable and lists zero analyses. It does not report a comparative effect estimate, confidence interval, or p-value.

The study summary describes three aims and says only studies for Aim 1 were completed. Neurocognitive Function is listed as a secondary outcome. Serious adverse events are listed as zero affected in each arm; other adverse events are listed as one affected in each arm. Death counts, analysis populations, missing-data handling, and detailed statistical methods are not reported in the registry record.