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 Home-based Transcranial Direct Current Stimulation (tDCS) for Behavioral Symptoms in Alzheimer's Disease and Related Dementias (ADRD) (NCT05478681), a na na study. The primary outcome is Acceptability of the tDCS Treatment as Assessed by the tDCS Acceptability Questionnaire.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05478681 |
| Phase | NA |
| Condition | Alzheimer Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 3 |
| Arms in the primary outcome | n/a |
| Lead sponsor | The University of Texas Health Science Center, Houston |
| Results posted | Yes |
2. Clinical Question
Population
People with Alzheimer’s disease and related dementias who have behavioral symptoms were the intended population. The registry lists Alzheimer disease as the condition and reports enrollment of 3 participants. It does not report further participant characteristics in the information available for this record.
Intervention
All participants were assigned to receive active, home-based transcranial direct current stimulation (tDCS). The registry describes constant current intensity of 2mA, with anodal stimulation over the left dorsolateral prefrontal cortex and the cathodal electrode positioned over the right dorsolateral prefrontal cortex. Caregivers were to help set up and administer the stimulation.
Comparator
There was no separate comparator group. The registry identifies the study model as single group and does not list an allocation scheme or control arm. Therefore, the study was not designed as a randomized comparison of active tDCS with another intervention or with no stimulation.
Primary question
The primary outcome concerned acceptability of tDCS, assessed at week 2 with the tDCS Acceptability Questionnaire. Its total score ranges from 0 to 100, with higher scores indicating greater acceptance. The registry states that outcome data are not reported because only 1 of the 3 enrolled participants completed the study and results were withheld to protect participant privacy and confidentiality.
In general, a study of acceptability asks whether participants can and will engage with an intervention, rather than establishing a treatment effect against a comparator. That question is especially relevant to an intervention administered at home with caregiver assistance: practical participation and perceived acceptability can affect whether a larger study is feasible. However, the record does not report questionnaire scores or a summary of participants’ responses. It therefore does not quantify acceptability for this study.
3. Trial Design
The registry describes a completed, single-group study of active tDCS for behavioral symptoms in Alzheimer’s disease and related dementias. It records enrollment of 3 participants and identifies The University of Texas Health Science Center, Houston as the sponsor. The study start date is 2023-04-17, and the primary completion date is 2024-02-26. The phase is listed as NA.
All participants were to receive active tDCS; no alternative intervention or untreated control group is listed. Allocation is recorded as NA, and masking is listed as none. Accordingly, there is no randomized, like-for-like comparison in this study. The design can describe outcomes among those enrolled and receiving the intervention if such data are reported, but it cannot by itself separate intervention-related change from other explanations for change over time.
The intervention description specifies a constant current intensity of 2mA. Anodal tDCS was applied to the left dorsolateral prefrontal cortex, and the cathodal electrode was positioned on the right dorsolateral prefrontal cortex. Caregivers were expected to help set up and administer the stimulation. The registry does not report further implementation details in the record.
The primary outcome was acceptability measured by the tDCS Acceptability Questionnaire at week 2. Secondary outcomes listed are dementia-related behavioral symptoms assessed by the Neuropsychiatric Inventory (NPI-Q), apathy assessed by the Brief Dimensional Apathy Scale (b-DAS), depressive symptoms assessed by the Cornell Scale for Depression in Dementia (CSDD), and cognition evaluated by the Mini-Mental State Examination (MMSE). The record lists 11 outcome measures overall, but reports no analyses. It states that no outcome data are reported because only 1 participant completed the study and the low enrollment number prompted withholding data to protect privacy and confidentiality.
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 | Active tDCS |
|---|---|
| STARTED | 3 |
| COMPLETED | 1 |
| NOT COMPLETED | 2 |
Analysis population for the primary outcome, as defined in the registry: Only 3 participants were enrolled in this study. Of the 3 participants only 1 completed the study. Based on the low enrollment number, no data is reported here in order to protect and maintain participant privacy/confidentiality.
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.
Population: Only 3 participants were enrolled in this study. Of the 3 participants only 1 completed the study. Based on the low enrollment number, no data is reported here in order to protect and maintain participant privacy/confidentiality.
| Characteristic | Unit | Active tDCS |
|---|---|---|
| Participants analysed | 0 | |
| Age, Categorical: <=18 years | — | |
| Age, Categorical: Between 18 and 65 years | — | |
| Age, Categorical: >=65 years | — | |
| Sex: Female, Male: Female | — | |
| Sex: Female, Male: Male | — | |
| Ethnicity (NIH/OMB): Hispanic or Latino | — | |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | — | |
| Ethnicity (NIH/OMB): Unknown or Not Reported | — | |
| Race (NIH/OMB): American Indian or Alaska Native | — | |
| Race (NIH/OMB): Asian | — | |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | — | |
| Race (NIH/OMB): Black or African American | — | |
| Race (NIH/OMB): White | — | |
| Race (NIH/OMB): More than one race | — | |
| Race (NIH/OMB): Unknown or Not Reported | — | |
| Region of Enrollment: United States | participants | — |
6. Primary Endpoint
The registry lists the primary outcome as Acceptability of the tDCS Treatment as Assessed by the tDCS Acceptability Questionnaire, measured over week 2.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is acceptability of tDCS, measured at week 2 with the tDCS Acceptability Questionnaire. The registry describes a total score from 0 to 100; higher scores indicate greater acceptance of the tDCS treatment. No score, distribution, or other summary of this endpoint is reported in the registry record.
In general, an acceptability measure captures participants’ views about an intervention and can address whether the intervention is acceptable to those asked to use it. Such information can be useful when evaluating an intervention delivered at home, particularly when setup and administration involve caregiver assistance. Acceptability is distinct from clinical efficacy: a favorable acceptability score would not, by itself, establish a change in behavioral symptoms or cognition. Conversely, a symptom measure does not directly answer whether participants find an intervention acceptable.
The choice of an acceptability questionnaire as the primary outcome fits the stated purpose of assessing whether home-based tDCS is acceptable, alongside the study’s stated interest in safety and ADRD-related symptoms. The record does not report the questionnaire’s individual items, scoring procedure beyond the total-score range and direction, or a threshold for interpreting a score. No threshold or judgment about acceptability can therefore be applied to this study’s results. Because the results are withheld, the endpoint’s observed value and its precision are not available.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted record establishes that 3 participants enrolled and that only 1 completed the study. It does not provide a primary endpoint result. The registry explains that, given the low enrollment number, no data are reported in order to protect and maintain participant privacy and confidentiality. As a result, the acceptability questionnaire cannot be summarized numerically, and the record does not permit an estimate of the level or variability of acceptability among participants.
The record identifies the study as completed, but completion status does not mean that outcome data are available. The absence of a reported result is not evidence that acceptability was high or low. Nor does it indicate that the questionnaire was completed in a particular way. There is no reported estimate, confidence interval, or statistical test for the primary endpoint. There are also no reported analyses for the other outcomes.
The trial used a single group receiving active tDCS, without a comparator. In general, a single-group study can describe observed outcomes among participants, but a change over time cannot be attributed to the intervention with the same comparative basis as a randomized control design. Natural fluctuation, other care, measurement variation, and changes in participants’ circumstances can also be relevant explanations. In this record, no outcome values are available to describe change in the first place.
The secondary measures cover behavioral symptoms, apathy, depressive symptoms, and cognition. These are distinct outcome domains, and their scales do not necessarily measure interchangeable aspects of participants’ experiences. The registry lists 11 outcome measures overall, while the listed secondary outcomes include these four named instruments. It reports 0 analyses. The available record does not establish whether the instruments were administered, whether data were collected at additional times, or whether any unreported analyses were undertaken.
Safety results also require cautious reading. The adverse-event record lists zero participants at risk and zero serious and other events in the active tDCS group. Since the group’s recorded number at risk is zero, these entries do not provide an informative estimate of event frequency among exposed participants. They should not be interpreted as evidence that no participant experienced an adverse event. The record also does not provide event descriptions or further safety summaries.
Overall, the registry documents a small completed study and its intended outcomes and intervention, but it does not provide results that quantify acceptability, symptoms, cognition, or safety. The primary outcome’s precision cannot be assessed without an estimate and uncertainty measure. Any broader conclusion about the intervention’s effects or acceptability would go beyond what the posted data show.
9. Statistical Methods Explained
The record describes a single-group study in which all participants were to receive active tDCS. Allocation is listed as NA, and masking as none. These design features matter when interpreting results. In general, random allocation creates a basis for comparing groups by reducing systematic differences at the outset, while a comparator helps distinguish changes associated with an intervention from changes that might have occurred otherwise. This study does not provide that between-group comparison. Even if within-person measurements had been reported, they would not alone establish that the intervention caused a change.
The primary endpoint is a questionnaire total score with a stated range from 0 to 100 and a direction in which higher scores mean greater acceptance. In general, a score is a measurement on a defined scale, and its interpretation depends on the scale’s content, scoring rules, and context. A summary such as a mean or median can describe the center of observed scores, while a measure of spread describes how much scores vary. These summaries answer different questions: a central estimate does not show whether individual responses were similar or widely dispersed. No such summaries are reported for this endpoint.
In general, an estimate is more informative when accompanied by an uncertainty interval. A confidence interval describes a range of values compatible with the data under the statistical method and its assumptions; it is not a guarantee that the true value lies within that particular interval. With very limited information, estimates can be imprecise, and uncertainty may be substantial. Here, however, no primary outcome estimate or interval is posted. Precision cannot be evaluated from the questionnaire’s score range alone.
The registry names four secondary outcome instruments: the NPI-Q for dementia-related behavioral symptoms, the b-DAS for apathy, the CSDD for depressive symptoms, and the MMSE for cognition. The record lists 11 outcome measures overall and 0 analyses. A listed outcome is not the same as a reported analysis. The record does not provide the observed scores, the analysis method used for any outcome, or the results of comparisons across time. It is therefore not possible to assess estimates, variability, or evidence against a statistical null hypothesis for these measures.
In general, repeated measurements may be analyzed by examining within-person changes, but the appropriate method depends on the measurement schedule, outcome type, and analysis plan. A model for continuous scores may differ from an approach for counts or categorical outcomes. A model may also need to account for repeated observations from the same participant, because those observations are usually related rather than independent. The registry information does not report the planned statistical model or enough outcome data to identify what analysis was performed.
In general, over-dispersion matters when count data vary more than a chosen statistical model expects. If ignored, the model may understate uncertainty and produce intervals that are too narrow or tests that are too optimistic. This is a general issue in analyses of count outcomes, not a finding about this study: the record does not report the data or a count-model analysis needed to assess it.
Multiplicity is another general statistical concern when several outcomes or tests are examined. The chance of at least one apparently notable finding can increase as the number of tests increases, depending on how the tests are conducted. A prespecified hierarchy, adjusted testing strategy, or clear distinction between primary and exploratory outcomes can help with interpretation. The record identifies a primary endpoint and lists secondary outcomes, but does not report a multiplicity procedure or a statistical analysis plan. No claim about adjustment or lack of adjustment in an actual analysis can be made from the record.
Sample-size planning and power are also general design concepts. A planning calculation relies on assumptions about the outcome, the effect worth detecting, variability, design, and analysis. Such a calculation is not an observed result and cannot replace an estimate from collected data. The registry record does not report a trial-specific sample-size justification, target enrollment rationale, or assumptions for a planned power calculation. No trial-specific power claim should be inferred.
Finally, an analysis population defines which participants’ data are included in a particular analysis, for example based on enrollment, receipt of an intervention, or completion of measurements. Different population definitions can affect interpretation, especially when completion is limited. The record reports enrollment of 3 and completion by only 1 participant, but does not report analysis populations or how incomplete observations would be handled. It also does not give an estimate that could be recalculated from summary statistics. Therefore, there is no recalculated result to compare with a sponsor analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 11 outcome measures overall and reports 0 analyses. It identifies acceptability at week 2 as the primary outcome and names secondary measures covering behavioral symptoms, apathy, depressive symptoms, and cognition. It does not report a statistical analysis plan, a hierarchy among secondary outcomes, or a method for addressing multiplicity. Without reported analyses, there are no posted tests or estimates whose multiplicity handling can be evaluated.
In general, examining several outcomes can make isolated findings harder to interpret, because multiple opportunities for statistical signals may affect the chance of a notable result. A prespecified approach can distinguish the main question from secondary or exploratory questions. This is a general interpretive issue; it is not evidence that any particular adjustment was or was not applied in the study.
The record states that only 1 of the 3 enrolled participants completed the study. It does not report participant-level data, reasons for noncompletion, missingness by outcome, or a method for handling missing observations. The stated reason for not reporting outcome data is protection of privacy and confidentiality given the low enrollment. That reporting decision leaves the outcomes unavailable for statistical interpretation; it does not establish what values were observed or why measurements may be absent.
The registry does not define an analysis population, such as which enrolled participants would be included for each outcome, and does not describe an intention-to-treat or other analysis set. It also does not report imputation, complete-case analysis, or sensitivity analyses. These details are therefore not reported in the registry record. With one participant completing, any claim about how missingness affected an estimate would be unsupported, and no outcome estimate is available to assess.
11. What the Result Does, and Does Not, Mean
The record supports a limited descriptive account: this was a completed single-group study of home-based active tDCS; 3 participants enrolled, and 1 completed. The primary question concerned acceptability at week 2, assessed with a questionnaire whose score ranges from 0 to 100, with higher scores indicating greater acceptance. The registry explicitly states that no data are reported because the low enrollment number raised privacy and confidentiality concerns.
This means the posted record does not establish a measured level of acceptability. It cannot show whether participants’ scores were high, low, or varied. It also cannot show whether symptoms, apathy, depressive symptoms, or cognition changed, because no analyses are reported and no outcome values are provided. A completed study status does not supply the missing endpoint results.
In general, a single-group study does not provide a randomized control comparison. If outcomes were available, the design could describe what happened in the enrolled participants, but observed change alone would not isolate the intervention as its cause. Here the lack of reported outcomes further limits interpretation: no direction or size of change can be described, and no precision estimate can be assessed.
The adverse-event entries list zero at risk and zero events in the active tDCS group. Because the record lists zero participants at risk, those entries do not establish that exposed participants had no adverse events. They do not provide an interpretable event rate or a basis for a broader safety conclusion.
These limitations do not imply that the intervention was ineffective, unacceptable, or unsafe. They mean that the registry results available for this study do not answer those questions quantitatively. Conclusions should stay within the documented design, enrollment and completion information, and the explicit absence of reported outcome data.
12. Why This Trial Matters Statistically
This study raises an important statistical distinction between a trial being completed and its results being available for analysis. The registry marks the study completed, but reports no analyses and withholds outcome data for privacy and confidentiality because enrollment was low. Readers therefore need to separate the existence of a registered study and its planned measurements from evidence that can be evaluated statistically.
The study also illustrates the interpretive limits of a single-group design. Without a comparator, outcome changes cannot be evaluated against a concurrent control condition. This matters even when a study’s aims include feasibility, acceptability, safety, or symptom outcomes: each question requires an appropriate measurement and enough reported information to describe the result. In this record, the primary acceptability measure is defined, but its result is not reported.
Completion is limited relative to enrollment: 3 participants enrolled, and only 1 completed. That information is central to judging how much can be learned from the study, but the registry does not give outcome estimates or details about noncompletion. As a result, readers cannot assess variability, uncertainty, or the influence of missing observations. Nor can they determine whether the listed secondary measures yielded analyzable data.
In general, transparent reporting of outcome estimates, uncertainty, analysis populations, and missing-data methods helps readers distinguish a precise finding from an uncertain one and a null result from an unreported result. Here, those statistical details are not reported in the registry record. The case is therefore a reminder that a stated outcome and a completed study do not, by themselves, provide evidence about the outcome’s observed value.
13. 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 for statistical interpretation is the absence of outcome results. The registry says that only 1 of the 3 enrolled participants completed the study and that no data are reported to protect participant privacy and confidentiality. Consequently, the primary acceptability score and secondary outcome values cannot be examined, and no effect estimate or uncertainty measure is available.
The design is single group, with allocation listed as NA and masking listed as none. There is no comparator arm for a like-for-like contrast. In general, this limits causal interpretation because changes cannot be distinguished from other possible influences using a randomized comparison. The registry does not report an analysis that could address this limitation.
The record lists 11 outcome measures and 0 analyses. It does not report a statistical analysis plan, a multiplicity strategy, analysis populations, or methods for handling missing data. The completion information is limited to the statement that only 1 participant completed; reasons for noncompletion and outcome-specific missingness are not reported in the registry record.
The adverse-event entries list zero participants at risk as well as zero serious and other events. This does not provide an informative estimate of safety among exposed participants. The registry also does not provide additional event descriptions or a safety analysis. These limitations are specific to the information recorded for this study and restrict conclusions about its outcomes; they do not establish that an unreported outcome had any particular value.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Home-based Transcranial Direct Current Stimulation (tDCS) for Behavioral Symptoms in Alzheimer's Disease and Related Dementias (ADRD) — NCT05478681.
- Registry record last updated 2025-10-10; status last verified 2025-09.
- Results first posted 2025-10-10.
- 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.
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17. Record Summary
The registry record describes a completed, single-group study of home-based active tDCS for behavioral symptoms in Alzheimer’s disease and related dementias. The sponsor is The University of Texas Health Science Center, Houston. The study began on 2023-04-17, with primary completion on 2024-02-26. Enrollment was 3; only 1 participant completed.
Participants were to receive active tDCS at a constant current intensity of 2mA, with caregiver assistance in setup and administration. The primary outcome was acceptability at week 2, measured by a questionnaire scored from 0 to 100, with higher scores indicating greater acceptance. Secondary outcomes included behavioral symptoms, apathy, depressive symptoms, and cognition.
The registry reports 0 analyses and states that outcome data are not reported because of low enrollment and privacy and confidentiality concerns. The adverse-event record lists zero participants at risk and zero events, which does not establish an event rate among exposed participants. Allocation is NA, masking is none, and no comparator group is listed.