Escitalopram Effects on CSF Amyloid Beta: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Escitalopram Effects on CSF Amyloid Beta (NCT02161458), a randomized phase 4 study. The primary outcome is Amyloid Beta Levels in CSF.

2. Clinical Question

The study is registered as NCT02161458, titled “Escitalopram Effects on CSF Amyloid Beta.” Its stated scientific context is the investigation of whether an SSRI may affect amyloid beta peptide levels, a major constituent of amyloid plaques. The measured outcomes are CSF peptide levels, not clinical symptoms, cognition, dementia incidence, or plaque burden directly.

The registry records enrollment of 98 participants. That total does not, by itself, establish how many participants contributed data to each outcome comparison. The serious adverse event records list different numbers at risk across groups, and the registry record does not provide a primary outcome analysis population or a complete account of outcome availability.

3. Trial Design

This was a randomized, double-masked, parallel-group Phase 4 trial sponsored by the University of Pennsylvania. The registry lists the study status as completed, enrollment as 98, a start date of 2014-06, and primary completion in 2017-08. The registry record does not report the allocation ratio, the method used to generate the randomization sequence, or the details of how masking was maintained.

Four intervention descriptions appear in the record: escitalopram 20mg for 2 weeks, escitalopram 20mg for 8 weeks, escitalopram 30mg for 8 weeks, and placebo. The arm descriptions describe cognitively normal adults aged 60-85 and planned CSF measurement at baseline and after treatment. Escitalopram regimens included upward titration. The placebo description refers to treatment for 2 weeks or 8 weeks, rather than specifying one uniquely matched duration in this discussion available in the registry record.

A parallel-group design assigns participants to a group and compares outcomes across groups, rather than having every participant receive each intervention in sequence. Randomization is intended to make the groups comparable on average at the start of the study; it does not guarantee identical groups, especially in a study of limited size. Double masking means that the registry identifies two masked parties, but it does not specify their identities or operational procedures.

The registry record does not report how many participants were randomized to each arm, how many completed their assigned regimen, or how many had usable baseline and follow-up CSF results. Safety records list 22 at risk for the 20mg 2-week group, 29 for placebo, 28 for the 30mg 8-week group, and 8 for the 20mg 8-week group. Those safety denominators should not be assumed to be the outcome-analysis sample sizes. The registry record also does not report the protocol’s sample-size justification or whether the enrollment target changed.

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

Reasons for not completing this period:

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 Amyloid Beta Levels in CSF, measured over 2 - 8 Weeks (we used week 8 minus baseline and week 2 minus baseline).

The primary endpoint is described as amyloid beta levels in CSF, expressed in pg/mL. The registry specifies a mean and standard deviation as the summary format. The outcome description focuses on change from baseline in amyloid beta 42 and amyloid beta 40 after exposure to escitalopram. The timeframe is described as 2 - 8 Weeks, using week 2 minus baseline and week 8 minus baseline.

CSF concentrations are a biological measurement. They can be used to study whether a treatment exposure is associated with a change in the measured peptide levels, but a change in a CSF measure is not itself a direct measure of cognition, daily function, or future disease. The registry’s rationale relates amyloid beta to plaques, but the endpoint is CSF peptide concentration, not an imaging measure of plaques or a clinical diagnosis.

Baseline-to-follow-up change gives a way to express how a participant’s measured level differs from their own starting value. For a randomized comparison, the key question is generally whether the average change differs across assigned groups, with the comparison and its uncertainty made explicit. The record does not post group means, change estimates, between-group contrasts, confidence intervals, or p-values for this primary endpoint. It therefore does not allow the magnitude or precision of the measured changes to be evaluated.

The outcome encompasses two amyloid beta peptides and more than one follow-up period. The registry record does not specify a single primary peptide-by-time comparison in the posted results. Its outcome information consequently establishes what was measured, but does not establish which individual comparison should be treated as the definitive estimate.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

The registry describes the primary outcome as a continuous measure summarized by a mean and standard deviation. In general, a mean is the arithmetic average of measured values. For a change outcome, each participant’s follow-up value is compared with that participant’s baseline value, and a group mean can describe the average change. A standard deviation describes how dispersed the observed participant values are around their mean. It does not directly state how certain the estimated mean is, and it does not give the size of a treatment difference between groups.

To address the comparative question, an analysis would ordinarily need to define a contrast between assigned groups, such as the difference between average changes. The estimate describes the observed contrast; its uncertainty describes how much it might vary because of sampling and measurement variability. The registry record does not report the contrast, its uncertainty, or the method used to obtain it. It therefore cannot be determined whether the posted analysis compared change scores, adjusted follow-up values for baseline, or used another approach.

Why distinguish within-group change from a between-group comparison?

General statistical context: a change within one group does not by itself establish that the group changed differently from another group. Both groups may change over time for reasons unrelated to the assigned treatment, including natural variation or features of measurement. A randomized comparison focuses on the difference between groups, rather than interpreting a change in one group in isolation. The registry record describes baseline and follow-up measurement but does not post the relevant between-group estimates.

Baseline adjustment is one possible analysis approach for continuous outcomes. In general, it uses baseline measurement information when estimating a follow-up group contrast. A change-score approach instead analyzes the difference between follow-up and baseline for each participant. These approaches can have different statistical properties depending on the data and model assumptions. The registry record does not report which approach was used, so no claim should be made about its statistical model.

What does a confidence interval add?

General statistical context: a confidence interval expresses uncertainty around an estimate under the assumptions of the analysis. It can help readers judge whether the data are compatible with a range of effect sizes, rather than relying only on whether a test crosses a threshold. Its width depends on such factors as sample size and variability. A p-value, if reported, addresses compatibility of the data with a specified null model; it is not the probability that the null hypothesis is true, nor does it measure clinical importance.

No confidence interval, standard error, or p-value for the primary endpoint appears in the registry record. The absence of these quantities means that statistical precision and evidence against a no-difference model cannot be assessed from the posted results. It would be inappropriate to infer statistical significance or its absence from the study’s design description or from the fact that the registry marks the trial completed.

How should multiple peptides and time points be considered?

The endpoint includes amyloid beta 42 and amyloid beta 40, and the listed timeframe uses change at week 2 and week 8. This creates more than one possible comparison. In general, testing multiple outcomes or time points can increase the chance of at least one apparently unusual result when each is assessed separately. Multiplicity methods can address that issue, or a protocol can identify a primary comparison in advance and treat other comparisons as secondary or exploratory.

The registry record does not report a multiplicity strategy, a hierarchy of comparisons, or which peptide and follow-up time were designated as the primary contrast. It also does not post separate estimates for these combinations. As a result, the reader cannot determine how the trial’s analyses distinguished confirmatory comparisons from other outcome assessments.

What do the planning assumptions mean?

General statistical context: sample-size planning asks how many participants may be needed to detect a target effect under stated assumptions. The record describes planning illustrations based on an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also says the target effect is a stated fraction of the observed effect. These are planning assumptions, not a report of the trial’s observed treatment effect.

Any planning quantity based on an observed effect is sensitive to that effect estimate and to the assumptions used. A sample-size illustration does not show that the trial had a particular probability of detecting an effect after it was conducted. That distinction is important: observed power is not a substitute for reporting the estimate and its confidence interval. The registry record does not report the trial’s own sample-size justification, and the numerical planning results are not included in the information available for interpreting the primary outcome.

Normal approximations are general methods that rely on a model for the distribution of an estimator. Whether such an approximation is suitable depends on the data and analysis. The record does not provide enough outcome data or analysis details to assess distributional assumptions, outliers, or any potential over-dispersion. Over-dispersion is a general concern when observed variability exceeds what a statistical model assumes; it can make standard errors too small if not accounted for. No claim can be made that this issue arose in this trial.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome covers amyloid beta 42 and amyloid beta 40, with change assessed at week 2 and week 8. The registry record also describes multiple escitalopram regimens and placebo. This makes the definition of the primary comparison important: different choices of peptide, follow-up, and treatment contrast answer different questions. The registry record does not report a multiplicity adjustment, an ordered testing strategy, or a clearly designated single comparison in the posted results. It also does not provide analyses that would allow readers to see how each outcome and time point was handled.

Missing data are another important consideration for a baseline-to-follow-up outcome. In general, a participant without a usable follow-up measurement cannot contribute a complete change score unless an analysis method addresses the missing value. Different assumptions and methods for missing observations can affect estimates and their uncertainty. The registry record does not report the number of missing primary outcome measurements, reasons for missingness, or any method for handling missing data.

The record does not state whether the analysis included all randomized participants, only participants who completed treatment, or another analysis population. It also does not report outcome-specific denominators or the treatment of participants who deviated from assigned regimens. Enrollment of 98 and the safety denominators do not identify the primary outcome analysis population. These omissions limit assessment of possible selection effects and the robustness of any result.

The registry record does not report an interim analysis plan or stopping rules. Their absence from the record should not be taken as evidence that a particular procedure was or was not used. Likewise, details of protocol deviations and post-randomization exclusions are not reported in the registry record.

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 5% reporting threshold.

The safety records list serious adverse events in four groups: 0 among 22 at risk for escitalopram 20mg for 2 weeks, 0 among 29 at risk for placebo, 0 among 28 at risk for escitalopram 30mg for 8 weeks, and 0 among 8 at risk for escitalopram 20mg for 8 weeks. The record also lists 0 deaths in each group. The other adverse-event field likewise lists 0 affected participants in each group, with the same at-risk denominators.

These figures describe what the registry reports for the listed groups; they are not estimates of comparative safety. Zero recorded serious events does not establish that the true risk is zero. In general, when no events are observed, uncertainty about the event rate remains, especially when the number at risk is limited. No confidence intervals or statistical comparisons for safety are reported.

The registry record does not provide detailed definitions, event collection procedures, exposure-adjusted rates, or the timing of safety follow-up. The at-risk numbers differ by group and should not be treated as the number enrolled in each primary outcome analysis. The figures should therefore be read as event counts within the recorded safety groups, not as proof of absence of adverse events or as a complete account of tolerability.

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

The record establishes that a randomized, double-masked, parallel-group Phase 4 trial studied escitalopram regimens and placebo in relation to CSF amyloid beta levels in cognitively normal older adults. The primary outcome was defined around changes in amyloid beta 42 and amyloid beta 40 from baseline, with measurements at 2 weeks and 8 weeks. Those details describe the study question and what it intended to measure.

The registry record does not post the primary outcome estimates. It gives no group means, mean changes, between-group differences, confidence intervals, or p-values. Consequently, the posted results do not establish the direction or magnitude of any measured difference, or how precisely it was estimated. The lack of a reported estimate is not evidence that there was no difference; it leaves the outcome question unanswered in the registry record.

Even if a difference in CSF peptide levels were reported, it would need to be interpreted as a difference in this biological measure, at the measured time point and in the study population. It would not automatically show a difference in cognition, symptoms, clinical diagnosis, or long-term outcomes. The study rationale mentions amyloid plaques, but the endpoint described in the record is CSF concentration, not a direct measure of plaque burden.

The study’s randomized, masked design is relevant to how comparisons may be interpreted, but design labels alone do not determine the quality or precision of an analysis. Readers would also need estimates, uncertainty, analysis populations, missing-data information, and clarity about which comparisons were primary. Those details are not reported in the registry record. The safety counts are also limited to the event categories and denominators that the record lists; zero recorded events should not be read as proof that risk is absent.

Accordingly, the record supports a description of the trial’s design, population, interventions, and intended endpoint, but not a conclusion about the result of the primary question. It cannot be used on its own to claim that escitalopram changed or did not change CSF amyloid beta, or to infer a clinical effect beyond the measured biomarker.

13. Why This Trial Matters Statistically

This trial is statistically notable because its primary outcome combines a continuous biomarker with multiple peptides and follow-up periods. Such an outcome requires clear reporting of the exact comparison: which peptide, which treatment regimen, which follow-up, and what group contrast. Without that clarity, a reader cannot tell which estimate answers the central question or how to interpret other analyses.

Its randomized, double-masked, parallel-group design provides a framework for comparing assigned groups. However, the registry record does not report the primary outcome estimates or analysis details. This illustrates why design information alone is not enough to assess evidence: readers also need the effect estimate, uncertainty, analysis population, and information about missing measurements and multiple comparisons.

The record reports an overall enrollment of 98 but does not report the number analyzed for each primary outcome comparison. The safety denominators vary across groups, underscoring that group-specific counts can differ by purpose and should not be substituted for outcome denominators. Transparent participant flow and outcome availability would help readers distinguish planned enrollment from the data contributing to an estimate.

The study also demonstrates the distinction between a biomarker endpoint and a clinical endpoint. CSF amyloid beta measurements can address a biological question, but they do not alone establish effects on cognition, symptoms, or future disease outcomes. Statistically, the interpretation should remain tied to the specific variable and follow-up assessed.

Finally, planning illustrations based on observed effects answer a different question from the trial’s outcome analysis. They can describe hypothetical future sample-size requirements under stated assumptions, but they do not show how strong or precise the observed evidence is. Reporting outcome estimates and their uncertainty is necessary for that assessment.

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 trial record is that no primary outcome analysis estimates are posted. The outcome has several peptides and time points, and the registry indicates that it was not reduced to one comparison. Without group-level summaries or between-group contrasts, the main scientific question cannot be answered from the record.

Important analysis details are also not reported: outcome-specific sample sizes, the analysis population, the handling of missing CSF measurements, the statistical model, baseline adjustment, and the approach to multiplicity. The registry record does not identify a single primary peptide-by-time comparison. These omissions prevent assessment of whether the analysis matched a prespecified plan and how sensitive any result might be to alternative choices.

The arm descriptions state intended regimens and measurement schedules, but the record does not report participant flow by arm or the number who completed each regimen. The safety denominators vary and should not be interpreted as primary endpoint denominators. The available safety summary also lacks detailed event definitions, follow-up procedures, and uncertainty estimates.

The population described is cognitively normal adults aged 60-85. The record does not provide further details about participant characteristics or eligibility criteria, so the representativeness of the enrolled group cannot be evaluated. The outcome is a CSF biomarker rather than a clinical measure, and the record does not report clinical outcome findings. These limitations constrain interpretation to the stated study question and prevent extrapolation to clinical outcomes.

The registry record does not report the protocol’s sample-size justification, interim analyses, or stopping rules. It also does not provide enough information to assess whether model assumptions were appropriate. These items should be treated as unreported, not presumed absent or present.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Escitalopram Effects on CSF Amyloid Beta — NCT02161458.
• Registry record last updated 2020-04-09; status last verified 2020-04.
• Results first posted 2019-03-12.
• 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

NCT02161458, “Escitalopram Effects on CSF Amyloid Beta,” is a completed, randomized, double-masked, parallel-group Phase 4 study sponsored by the University of Pennsylvania. The registry records enrollment of 98, a study start of 2014-06, and primary completion in 2017-08. The population described in the arm descriptions is cognitively normal adults aged 60-85.

The interventions were escitalopram 20mg for 2 weeks, escitalopram 20mg for 8 weeks, escitalopram 30mg for 8 weeks, and placebo. The primary outcome concerns change from baseline in CSF amyloid beta 42 and amyloid beta 40, measured in pg/mL, with follow-up at 2 weeks and 8 weeks. The registry record does not post primary outcome analysis estimates or details sufficient to assess their precision. Safety listings report 0 serious adverse events and 0 deaths in each group, with differing numbers at risk.