This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Treatment of Language and Memory in Patients With Alzheimer's Disease (NCT00593372), a randomized phase 1 study. The primary outcome is Number of Successful Memory Tasks Completed Over Study Period..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00593372 |
| Phase | Phase 1 |
| Condition | Alzheimer Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 11 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Arkansas |
| Results posted | Yes |
2. Clinical Question
Population
People with Alzheimer disease who, according to the registry summary, were taking cholinesterase inhibitors. The registry reports enrollment of 11 participants. It does not report further eligibility details or a fuller description of the enrolled population.
Intervention
Drug therapy plus behavioral intervention. The intervention is identified as Spaced Retrieval Training; the summary describes 16 treatment sessions with a Speech Language Pathologist during an 8-week period. Initial testing and interviews were used to help select potential communication or memory treatment goals.
Comparator
Drug therapy alone, also described in the arm information as continuing medication only. The summary says this group used a Caregiver Checklist for 8 weeks to monitor changes in identified communication difficulties.
Primary question
Over 8 weeks, what number of successful memory tasks was recorded for participants receiving spaced retrieval therapy, compared with participants continuing medication only? The registry defines successful tasks as tasks, such as remembering where keys are kept, that participants can answer consistently. It does not report an estimable statistical comparison between the groups.
3. Trial Design
The registry describes a randomized, open-label, parallel-group trial, marked Phase 1, with 11 participants enrolled. Participants were allocated to drug therapy plus behavioral therapy or drug therapy only. Because masking is listed as none, the trial was not masked according to the registry record. The registry lists the University of Arkansas as sponsor and gives the study status as completed.
The registry summary describes an initial assessment involving a written case history, communication-skills tests, and interviews with participants, family members, and staff caregivers. These assessments were intended to help identify potential treatment goals. In the behavioral group, the intervention is identified as Spaced Retrieval Training, and the summary describes 16 sessions with a Speech Language Pathologist during an 8-week period. The comparator group used a Caregiver Checklist during the same stated period to record changes in identified communication difficulties. A post-test was planned for all participants.
The arm descriptions and posted outcome labels use slightly different wording: the behavioral arm is described as both Drug Plus Behavioral Therapy and Spaced Retrieval Therapy, while the comparator is described as Drug Therapy Only and Continuing Medication Only. Both identify the same broad contrast between adding a behavioral intervention and continuing medication alone. The registry does not report further details about allocation procedures, adherence, treatment fidelity, or the content of the post-test.
The record gives a study start of 2003-08 and primary completion of 2010-04. These dates describe the registry’s study timeline; they do not establish how long any individual participant was followed. The protocol’s sample-size justification, planned interim analyses, and full statistical analysis plan are not reported in 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
| Stage | Spaced Retrieval Therapy | Continuing Medication Only |
|---|---|---|
| STARTED | 8 | 3 |
| COMPLETED | 8 | 3 |
| NOT COMPLETED | 0 | 0 |
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.
| Characteristic | Unit | Spaced Retrieval Therapy | Continuing Medication Only | Total |
|---|---|---|---|---|
| Participants analysed | 8 | 3 | 11 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 0 | 1 |
| Age, Categorical: >=65 years | Participants | 7 | 3 | 10 |
| Age, Continuous | years | 74 (SD 5) | 72 (SD 3) | 72 (SD 6) |
| Gender: Female | Participants | 2 | 2 | 4 |
| Gender: Male | Participants | 6 | 1 | 7 |
| Region of Enrollment: United States | participants | 8 | 3 | 11 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Successful Memory Tasks Completed Over Study Period., measured over 8 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | memory tasks |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the number of successful memory tasks completed over the 8-week study period. The registry describes successful tasks as memory tasks that participants are able to answer consistently, with remembering where keys are kept offered as an example. This endpoint is intended to capture performance on practical, individualized memory tasks rather than a general rating of memory alone.
Using tasks tied to everyday goals can make an outcome relevant to the intervention: spaced retrieval practice can focus on remembering particular information or routines. Repeatedly assessing whether a participant responds consistently can therefore describe performance on the selected tasks during the study period. This is a general explanation of the type of outcome, not evidence that the endpoint captures every aspect of memory or communication.
The registry does not describe how many tasks were selected for each participant, how consistency was defined, who assessed responses, or how scores were combined across participants. It lists 5 for the Spaced Retrieval Therapy group and 0 for the Continuing Medication Only group, with 8 and 3 participants respectively. The record does not clarify whether these values are group totals, averages, or another summary, and it provides no measure of variability for this endpoint. The endpoint is therefore clinically interpretable in broad terms, but the posted values alone do not provide enough statistical detail to establish the distribution of participant-level outcomes or a comparative effect.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry reports 8 participants in the Spaced Retrieval Therapy group and a value of 5 for its primary outcome. It reports 3 participants in the Continuing Medication Only group and a value of 0. These are the posted group values for successful memory tasks over 8 weeks. The record does not identify whether they are totals, means, or another type of group summary, so they should not be read as a participant-level difference or as a measure of how consistently individual participants performed.
No dispersion measure, confidence interval, or inferential test is posted for the primary outcome. The record also indicates that values were missing or not estimable for a two-arm comparison of this count outcome. Accordingly, a valid statistical comparison between the groups is not available in the registry record. The numerical contrast between the posted values should not be treated as an estimated treatment effect, nor does it establish how uncertain a comparison would be.
Small group sizes are important context for interpreting the record. With 8 and 3 participants, individual outcomes can have substantial influence on group summaries. This is a general statistical consideration; it does not establish what happened to any particular participant or explain why a comparative analysis was unavailable. Without participant-level results or a clearly defined group summary, readers cannot assess the spread of outcomes, identify outliers, or judge whether the posted values represent consistent patterns across participants.
The registry lists a secondary outcome, change on the Mini-Mental State Examination, but does not give a numerical result for it in the registry entries. It lists two outcome measures and zero analyses. The record therefore does not provide a reported secondary-outcome comparison to complement the primary endpoint.
The study’s randomized design describes how groups were intended to be formed, but randomization does not by itself supply an estimate, quantify uncertainty, or resolve the limitations of the posted outcome information. The results support only a description of the group values recorded in the registry. They do not establish the magnitude or precision of a between-group effect, and they do not establish whether the behavioral intervention caused a change in memory-task performance.
9. Statistical Methods Explained
What does a group summary tell us?
A group summary condenses participant outcomes into a value, but its meaning depends on how that value was calculated. For a count outcome, a group value might represent a total number of tasks, an average number per participant, or another summary. The registry lists values of 5 and 0 for the two groups but does not define which summary was used. Without that definition, readers should not interpret the values as directly comparable participant-level averages or totals.
Dispersion describes how much participant outcomes vary around a group summary. It matters because identical group summaries can arise from very different patterns: participants may have similar outcomes, or outcomes may vary widely. The registry provides no dispersion measure for the primary endpoint. Without participant-level data or a dispersion measure, it is not possible to assess the distribution of outcomes or quantify the uncertainty around a group summary.
Why is a comparative estimate needed?
A comparison should state the difference between groups using a defined scale and should indicate its uncertainty. A confidence interval is a statistical range that describes the precision of an estimate under the assumptions of the analysis. In general, a narrower interval indicates greater precision, while a wider interval indicates greater uncertainty. No comparative estimate or confidence interval is posted for the primary endpoint, and the registry indicates that a two-arm comparison was not estimable from the available count-outcome values. A numerical contrast between group entries is not a substitute for a defined estimate with an uncertainty measure.
For count outcomes, the analysis also depends on the distribution of the counts and on how observations are collected. A simple model may not adequately describe counts when variability exceeds what the model assumes; this is called over-dispersion. In general, over-dispersion can make standard errors too small if it is ignored, leading to overly narrow confidence intervals or misleading tests. The registry does not report a model, an assessment of over-dispersion, or an analysis method for this endpoint. There is therefore no basis in the registry record for attributing the unavailable comparison to a particular modeling choice.
What does the design information establish?
Random allocation is intended to form groups without deliberately assigning participants according to their expected outcomes. In general, this can reduce systematic differences between groups at the outset, but it cannot guarantee balance, especially in a small trial. A parallel-group design assigns participants to one of the groups for the comparison rather than describing a crossover. The registry lists the trial as randomized and parallel, and reports no masking. It does not provide further detail on sequence generation, concealment of allocation, or whether assessors knew the assigned group.
The comparator is described as continuing medication only, while the intervention group received behavioral therapy in addition to drug therapy. This contrast is relevant to the stated study question, but the registry does not report enough information to assess differences in attention, contact time, or other aspects of care between groups. Those details can affect interpretation in behavioral studies, particularly when outcomes involve performance on tasks selected and assessed during treatment.
How should planning calculations be understood?
Sample-size calculations are planning tools. The registry states that its planning illustration uses the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect expressed as a fraction of the observed effect. Such illustrations are not the trial’s original design rationale and are not observed power. They do not show that the completed study had adequate precision, nor do they replace an estimate and confidence interval from the trial. The original sample-size justification and planned statistical analysis are not reported in the registry record. No numerical planning results are stated in the registry entries used for this interpretation.
With no estimable comparison for the posted count outcome, planning based on an observed effect also needs cautious interpretation. In general, an effect estimated from a small study can be unstable, and sample-size illustrations based on that estimate inherit its uncertainty. This does not create a new estimate for this trial; it explains why planning outputs should be treated as illustrations rather than as evidence of the strength or reliability of the observed result.
What statistical conclusion is available?
The posted information supports a descriptive account of enrollment, group assignment, endpoint definition, and the two group values. It does not support a numerical estimate of the treatment contrast, a test of statistical significance, or a precision statement for that contrast. No p-value, confidence interval, or analysis model for the primary outcome is reported in the registry record. In general, statistical significance and clinical importance are distinct: a test addresses compatibility with a statistical null under specified assumptions, while clinical importance requires interpretation of the size and relevance of an effect. Neither can be assessed for this primary comparison from the posted statistical results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome, the number of successful memory tasks over 8 weeks, and one secondary outcome, change on the Mini-Mental State Examination. It reports two outcome measures and zero analyses. The registry record does not describe whether a multiplicity adjustment was planned or whether any outcome was designated for formal hypothesis testing beyond its primary or secondary label.
Multiplicity arises when several outcomes, time points, or analyses are tested. In general, conducting many tests can increase the chance of at least one apparently notable result even when no true effect exists. Prespecified analysis choices and, when appropriate, adjustment methods help readers understand that risk. The registry does not provide a statistical plan or a multiplicity approach, so it is not possible to determine how the listed outcomes were intended to be analyzed together.
Missing-data methods and analysis populations are also not described. The record does not state whether all randomized participants were included in each analysis, whether outcomes were available for every participant, or how missing measurements were handled. It therefore does not support assumptions about an intention-to-treat, per-protocol, or other analysis population. The registry’s statement that a two-arm comparison was not estimable for the primary count outcome is not an explanation of why the comparison was unavailable, and it should not be taken as evidence about the reason or extent of missing data.
These omissions limit assessment of bias and robustness. Without a reported analysis population, missing-data approach, and prespecified outcome-analysis plan, readers cannot determine whether the posted values reflect all enrolled participants or a subset, or whether analytic choices were made before results were known.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Spaced Retrieval Therapy | 0 | 8 | 0.0% |
| Continuing Medication Only | 0 | 3 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Spaced Retrieval Therapy | 0 of 8 |
| Continuing Medication Only | 0 of 3 |
The registry reports no serious adverse events among the 8 participants at risk in the Spaced Retrieval Therapy group and no serious adverse events among the 3 participants at risk in the Continuing Medication Only group. It also reports no other adverse events among those same group sizes. These figures describe events recorded in the registry; they do not establish that no unrecorded events occurred.
Deaths are listed as null for both groups, so death counts are not reported in the registry record. The registry gives no serious adverse-event terms, and the adverse-event information does not describe event definitions, collection procedures, duration of surveillance, or whether events were judged related to an intervention.
In general, a zero recorded event count in a small study does not establish that an intervention has no safety risks. The number of participants observed is limited, and the registry record does not provide enough detail to assess the completeness or length of adverse-event monitoring. These data should be read as the recorded counts for this study, not as a definitive safety comparison or a basis for conclusions beyond the information recorded.
12. What the Result Does, and Does Not, Mean
The registry records a randomized comparison of drug therapy plus a behavioral intervention with drug therapy alone, and it posts group values for a memory-task count outcome. The intervention group is listed with 8 participants and a value of 5; the continuing-medication group is listed with 3 participants and a value of 0. The endpoint concerns successful responses to memory tasks over 8 weeks, as defined in the registry.
The record does not explain whether these values represent group totals, averages, or another summary. It also provides no measure of variability and states that the values were missing or not estimable for a two-arm comparison. Consequently, the posted values cannot be used to quantify a reliable treatment effect or its precision. No statistical test or confidence interval for the primary comparison is reported.
The results do not establish that the behavioral intervention caused better memory-task performance. They also do not establish that it had no effect. The lack of an estimable comparison means that the registry’s posted outcome information does not resolve the comparative question. The listed secondary outcome, change on the Mini-Mental State Examination, has no numerical result in the registry entries, so it cannot add a quantitative comparison.
More generally, a randomized design is one feature of a study, not a guarantee that the reported results answer every clinical or statistical question. Interpretation also requires clearly defined outcome summaries, an analysis approach, estimates of uncertainty, and sufficient information about participants and missing measurements. Those details are not reported for this comparison. The appropriate reading is therefore descriptive and limited to the registry entries, rather than a conclusion about whether one treatment strategy is superior or whether the intervention is effective.
13. Why This Trial Matters Statistically
This trial is statistically notable for the gap between a clearly framed comparative question and the limited comparative information in the registry. It identifies a randomized, parallel-group contrast between adding behavioral therapy to medication and continuing medication alone, and it defines a practical memory-task endpoint over 8 weeks. Yet the registry does not provide an estimable two-arm comparison for that endpoint.
That distinction matters for clinical research interpretation. Group values alone do not necessarily tell readers what quantity has been estimated. A value of 5 or 0 has limited statistical meaning without knowing whether it represents a total, an average, or another summary, and without information about how participant outcomes vary. A transparent analysis would ordinarily clarify the estimand, describe the analysis population and method, and report an effect estimate with an indication of uncertainty. Those elements are not reported for the primary comparison in the registry record.
The enrollment of 11 participants also places the posted results in a small-study context. In general, small groups can yield unstable summaries and limited precision, while a lack of uncertainty measures makes that limitation harder to evaluate. The registry’s stated planning assumptions are illustrations rather than a record of the original trial design justification, and they are not observed power.
The study also highlights the importance of reporting how behavioral outcomes are operationalized. The endpoint is based on consistent responses to selected memory tasks, but the registry does not describe how tasks were chosen, scored, or summarized across participants. Such details are central to interpreting an outcome that may be individualized. The statistical lesson is not a conclusion about treatment, but the need for interpretable outcome definitions and transparent comparative analyses before group values can answer a trial question.
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 registry provides limited detail about the population beyond Alzheimer disease, medication use described in the summary, and total enrollment. It does not report detailed eligibility criteria, participant characteristics, disease severity, or the distribution of relevant baseline features between the groups. With 8 participants in one arm and 3 in the other, the record offers little basis for judging baseline comparability or how broadly the results may apply.
The intervention and comparator are described at a high level. The summary specifies 16 behavioral treatment sessions during an 8-week period and caregiver checklist monitoring in the comparator group, but does not report attendance, adherence, treatment fidelity, or the exact medication regimen. The registry also does not explain whether contact with clinicians or caregivers differed between groups apart from the described activities.
Outcome reporting is a central limitation. The registry does not define the group summary represented by the posted values, report variability, or provide a comparative estimate. It indicates that the two-arm comparison was not estimable for the count outcome. It does not report participant-level outcomes, the number or selection of memory tasks per participant, detailed scoring rules, or who assessed performance. The secondary Mini-Mental State Examination outcome is listed without a numerical result.
Further limitations include no reported statistical analysis plan, missing-data method, analysis population, or multiplicity approach. Masking is listed as none, and the registry does not say whether outcome assessors were masked. The adverse-event record gives counts but not surveillance details; deaths are not reported in the registry record. These omissions constrain evaluation of both the outcome findings and the completeness of safety reporting.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Treatment of Language and Memory in Patients With Alzheimer's Disease — NCT00593372.
- Registry record last updated 2017-01-09; status last verified 2016-11.
- Results first posted 2010-07-20.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
This completed Phase 1 study is listed as randomized, open-label, and parallel-group, with 11 participants enrolled. It compared drug therapy plus behavioral intervention, identified as Spaced Retrieval Training, with continuing medication only. The registry describes 16 behavioral treatment sessions during an 8-week period and caregiver checklist monitoring for the comparator group.
The primary outcome was the number of successful memory tasks over 8 weeks. The registry posts values of 5 among 8 participants for Spaced Retrieval Therapy and 0 among 3 participants for Continuing Medication Only, but does not define the type of group summary. A two-arm comparison is identified as not estimable, and no comparative estimate or uncertainty measure is reported. Change on the Mini-Mental State Examination is listed as a secondary outcome without a numerical result in the registry entries.
No serious or other adverse events are reported in either group; deaths are not reported in the registry record. The registry does not report the full statistical plan, analysis populations, or missing-data methods.