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 Cognitive Function in Elderly Marathon Runners (NCT01045031), a registered phase not stated study. The primary outcome is Brain-derived Neurotrophic Factor (BDNF).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01045031 |
| Phase | Phase not stated |
| Condition | Cognitive Decline |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 114 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medical University of Vienna |
| Results posted | Yes |
2. Clinical Question
Population
Older adults in an Austrian prospective cohort, with 114 participants enrolled. The record describes marathon runners and bicyclists alongside controls.
Intervention
There is no assigned treatment. The main exposure of interest is participation in extensive endurance exercise, represented by runners and bicyclists.
Comparator
Controls recruited through personal contact and advertisements. The record describes matching by age, sex and years of education; its study summary also mentions age, education, occupation and verbal intelligence.
Primary question
How do cognitive outcomes and Brain-derived Neurotrophic Factor levels in older endurance athletes compare with those of controls, including over the stated follow-up timeframe?
The study addresses a question about the relationship between endurance exercise and cognition in older adults. Its summary notes that the investigators were interested in whether the intensity of endurance training might matter, and that prior work had not established that relationship. The cohort was designed to compare neuropsychological performance in older marathon runners or bicyclists with controls.
The primary outcome listed is Brain-derived Neurotrophic Factor (BDNF), measured in ng/mL at baseline and 5 years. The record also lists self-rating questionnaires and Insulin-like Growth Factor (IGF-1) as secondary outcomes. It reports four outcome measures in total, but does not provide results for any of them. The question can therefore be described from the planned comparison, but the registry record does not establish what the observed cognitive or biomarker differences were.
This is an observational comparison, not a randomized test of an exercise program. The registry record does not state that participants were assigned to exercise or control status. Differences between groups could reflect characteristics associated with taking part in endurance events as well as exercise exposure itself. The specific analysis used to address such differences is not reported in the registry record.
3. Trial Design
This Austrian prospective cohort study is listed under the title “Cognitive Function in Elderly Marathon Runners.” Its official title is “Austrian Prospective Cohort Study in Cognitive Function of Elderly Marathon-runners.” The sponsor is Medical University of Vienna. The registry lists a start date of 2008-12, primary completion in 2014-02, enrollment of 114, and status as UNKNOWN.
The study summary describes a comparison of neuropsychological performance in elderly marathon runners or bicyclists with controls. The athlete description refers to runners participating in the 2008 Wachau half marathon and the Vienna City marathon, as well as bicyclists participating at the Corinthian marathon. Its inclusion criteria begin with participation in at least one of those events in the preceding two years and continued training, but the registry text is truncated before the full criteria are available. Further eligibility details are not reported in the registry record.
Controls were recruited through personal contact and advertisements. The arm description says they were matched according to age, sex and years of education. The study summary describes matching on age, education years, occupation and verbal intelligence. These descriptions are not identical, and the registry record does not explain the difference. It also does not establish that matching was used in the analysis.
The record identifies controls and athletes as the comparison groups, but does not state an allocation method. The registry explicitly identifies the comparison as non-randomized and cautions that the arms are not a like-for-like control comparison. This matters because enrollment in endurance events is not randomly assigned, so group characteristics may differ beyond the exposure being studied.
The primary outcome timeframe is baseline and 5 years. The registry record does not describe the schedule for the other outcomes, the full follow-up procedures, or whether all enrolled participants completed follow-up. Its status is UNKNOWN, and no outcome analyses are listed.
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 | Controls | Marathon Athletes |
|---|---|---|
| STARTED | 58 | 56 |
| COMPLETED | 49 | 50 |
| NOT COMPLETED | 9 | 6 |
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: Of 136 screened individuals (63 athletes, 73 controls), 56 athletes and 58 controls have been enrolled since they met the inclusion criteria.
| Characteristic | Unit | Marathon Athletes | Controls | Total |
|---|---|---|---|---|
| Participants analysed | 56 | 58 | 114 | |
| Age, Continuous | years | 66.0 (SD 4.7) | 65.9 (SD 4.1) | 65.9 (SD 4.4) |
| Sex: Female, Male: Female | Participants | 6 | 6 | 12 |
| Sex: Female, Male: Male | Participants | 50 | 52 | 102 |
6. Primary Endpoint
The registry lists the primary outcome as Brain-derived Neurotrophic Factor (BDNF), measured over Baseline and 5 years.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | ng/mL |
| Endpoint classification | Continuous Endpoint |
The primary outcome is Brain-derived Neurotrophic Factor (BDNF), a biomarker measured in ng/mL. The registry specifies reporting the mean and standard deviation, with measurements at baseline and 5 years. It does not provide the actual BDNF values, a group contrast, or an inferential result.
In general, the mean describes the average measurement in a group, while the standard deviation describes how dispersed individual measurements are around that average. Reporting both can help readers distinguish the group’s central value from the variation among participants. Neither statistic, on its own, indicates whether a difference between groups is precise or compatible with chance variation.
The registry identifies BDNF as the primary outcome, but does not explain the biological rationale for choosing it or specify how the result would be used to represent cognitive function. It separately lists neuropsychological performance in the study summary and names self-rating questionnaires and IGF-1 as secondary outcomes. The record does not report the instruments or tests used to assess cognition, or how those measures relate to BDNF.
The registry notes that baseline BDNF values differ from published data because levels had to be re-assessed from banked material following a manufacturer-based change of the analysis kit. This note is important for interpreting measurements across sources or time: the record flags a change in assay circumstances, but does not report the magnitude or direction of any resulting measurement difference. It also does not state whether the same kit was used for all measurements or how the change was addressed analytically.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study question, groups, primary outcome and planned measurement timeframe, but it does not report outcome results. No group means, standard deviations, changes over time, effect estimates, confidence intervals or p-values are listed. The analysis count is zero. Consequently, the posted record does not permit an estimate of the size or precision of any difference in BDNF or cognitive performance.
The enrollment is 114, and the adverse-event entries list 58 controls and 56 athletes at risk. These figures describe enrollment or risk-set information in the registry; they do not show how many participants contributed data to the primary outcome at baseline or 5 years. The number analyzed for BDNF and the handling of any loss to follow-up are not reported in the registry record.
The study summary says the investigators designed the cohort with adequate power. The record does not include a sample-size justification or assumptions that would allow that statement to be evaluated. Any planning illustration based on an observed effect is not a report of observed power and cannot substitute for outcome estimates. The specific observed effect and corresponding planning results are not reported in the registry record.
The comparison is observational. Matching is described, but the registry does not say whether the analysis accounted for matching, how any unmatched characteristics were addressed, or whether adjustments were made. In general, matching can make selected characteristics more comparable at recruitment, but it does not guarantee comparability on other factors. It also does not itself establish that a difference is caused by the exposure.
The registry mentions different matching characteristics in its study summary and control-arm description. It gives age, sex and years of education in one description, and age, education years, occupation and verbal intelligence in another. The record does not clarify which characteristics were actually matched or how matching was implemented.
The primary measure is scheduled at baseline and 5 years, but no longitudinal analysis method is reported. In general, a comparison of measurements at two time points can focus on endpoint values, within-person change, or differences in change between groups. Those approaches answer different questions, and the registry does not identify which one was planned or used. No result should be inferred from the timeframe alone.
Finally, the record states that baseline BDNF values differ from published data because banked samples were re-assessed following a manufacturer-based analysis-kit change. This is a relevant measurement caveat, but there are no posted values with which to assess its practical impact. The registry record supports a description of the intended cohort comparison, not a conclusion about the direction, magnitude, or precision of its findings.
9. Statistical Methods Explained
The study is a prospective cohort comparison. Participants are described according to whether they were endurance athletes or controls; the registry does not report random assignment. In general, a cohort study observes groups defined by an exposure or characteristic rather than assigning that exposure. This can be useful for studying real-world differences, but observed associations may reflect group differences as well as the exposure of interest.
What does the mean and standard deviation describe?
The primary outcome is BDNF in ng/mL, summarized using a mean and standard deviation. In general, the mean is the arithmetic average of the observed measurements. The standard deviation describes spread around that average on the same measurement scale. A small standard deviation relative to the mean indicates less variation among measured values than a larger one, but neither quantity alone describes uncertainty in the estimated group mean.
A standard deviation is not a confidence interval. In general, a confidence interval expresses uncertainty about an estimated quantity, such as a group mean or a difference between groups. Its width depends on the variability and amount of data, as well as the analysis. No confidence intervals are reported for this study, so the precision of its outcome estimates cannot be evaluated from the registry record.
How should the two-timepoint outcome be approached?
The BDNF timeframe is baseline and 5 years. In general, repeated measurements on the same participant are related: a person's later measurement may be associated with their earlier measurement. An analysis that accounts for this relationship can differ from one that treats observations as independent. Researchers may compare follow-up values, changes from baseline, or differences in change between groups. These are general options, not methods documented for this cohort. The planned or applied longitudinal method is not reported in the registry record.
Some participants may not have measurements at both time points. In general, missing follow-up data can reduce the information available and can affect estimates, particularly when the reasons for missingness are related to participants' outcomes or characteristics. The registry record does not report the amount or pattern of missing outcome data, reasons for missingness, or any method used to address it.
What does matching contribute?
The record describes controls as matched to athletes, but its descriptions of the matching characteristics differ. Matching can improve comparability on characteristics selected in advance. For an analysis, the matched structure may need to be accounted for, depending on how participants were matched and how outcomes are modeled. The registry does not report the matching procedure in enough detail to determine the structure, nor does it state whether analyses accounted for matching.
Matching does not ensure that groups are alike in every relevant respect. In an observational study, differences in characteristics that were not matched or measured may remain. Statistical adjustment can sometimes address measured differences, but it cannot automatically remove bias from unmeasured differences. The adjustment variables and model are not reported in the registry record.
How should uncertainty and significance be read?
In general, a p-value assesses how compatible data are with a specified statistical model and null hypothesis; it is not a measure of effect size or the probability that a hypothesis is true. A confidence interval is generally more informative about both the estimated effect and its uncertainty. Neither can be interpreted without knowing the estimate, analysis population and method. The registry record reports no p-values, confidence intervals or analysis results.
Over-dispersion is a concern in some data settings when variability is greater than a model assumes; ignoring it can make uncertainty estimates too small. This is a general statistical issue, not a documented feature of this study. The primary measure is continuous, and the registry does not state that over-dispersion was assessed or specify an outcome model.
What can planning calculations establish?
The record describes sample-size illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It says that the effect to detect is a stated fraction of the observed effect. Such illustrations describe planning scenarios under assumptions; they are not observed power and do not establish the precision of the study's actual results. The record does not provide its own sample-size justification, and the assumptions and calculated values do not establish that the cohort was adequately powered for the comparisons actually made.
The registry also notes that no allocation is stated and identifies the comparison as non-randomized. Equal allocation in a planning illustration is an assumption for that calculation, not evidence that the study assigned participants equally or randomly. In general, a statistical method can address only the question and data structure it was designed for; it cannot turn an observational comparison into a randomized one.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures, with BDNF identified as primary and self-rating questionnaires and IGF-1 listed as secondary outcomes. It does not describe the other outcome measure, the hierarchy among outcomes, or any procedure for handling multiple comparisons. A multiplicity plan is not reported in the registry record.
In general, testing many outcomes or comparisons can increase the chance of obtaining at least one apparently unusual result by chance. A prespecified primary outcome can help distinguish the principal question from additional analyses, but interpretation still depends on the analysis plan and the number of tests performed. Because the record lists no analyses or results, it is not possible to evaluate the impact of multiplicity on findings.
The analysis population is not described. The record does not state whether analyses were intended to include all enrolled participants, only those with complete measurements, or another population. It also does not report how many participants had primary outcome data at baseline or 5 years.
Missing-data methods are not reported in the registry record. There is no description of missing measurements, loss to follow-up, exclusions, or the assumptions used to handle incomplete records. In general, conclusions from a longitudinal cohort can depend on which participants contribute data at each time point and why data are unavailable. Without those details and posted results, the completeness and potential influence of missing data cannot be assessed.
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 |
|---|---|---|---|
| Controls | 0 | 58 | 0.0% |
| Athletes | 0 | 56 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Controls | 0 of 58 |
| Athletes | 0 of 56 |
The registry lists zero serious adverse events among 58 controls and zero among 56 athletes. It also records zero other adverse events in both groups, using the same at-risk counts. These are the figures entered in the adverse-event record; they are not a detailed account of how events were collected or reviewed.
The record does not describe the adverse-event collection period, definitions, monitoring procedures, or whether all participants were assessed in the same way. It also does not provide a list of serious event terms. Deaths are recorded as null, which means death information is not reported in the registry entry; it should not be read as a confirmed count of zero.
In general, a zero recorded count does not establish that no events occurred if reporting or follow-up is incomplete or unspecified. The registry's risk counts do not establish how many participants completed all study visits, and the record does not explain the relationship between adverse-event follow-up and the 5-year outcome timeframe. The figures should therefore be read narrowly as registry entries, not as evidence about risks beyond the reporting details available.
12. What the Result Does, and Does Not, Mean
The registry record describes an observational study of older endurance athletes and controls, with BDNF as the primary outcome and measurements planned at baseline and 5 years. It establishes the intended comparison and identifies some of the study's measurement and recruitment context. It does not report outcome analyses, so it does not show whether the groups differed in BDNF, cognitive performance, self-ratings or IGF-1.
It also does not provide estimates of effect size or precision. Without group summaries, contrasts, confidence intervals or p-values, the magnitude and uncertainty of any association cannot be assessed. The absence of posted results is not evidence that the groups were the same, and it is not evidence that they differed.
Even if results were available, an observational group comparison would not by itself show that endurance exercise caused an outcome. In general, athletes and controls may differ in characteristics other than exercise exposure. Matching on selected characteristics can improve comparability for those characteristics, but does not control all possible differences. The registry record does not report the analysis methods needed to evaluate adjustment or the remaining potential for confounding.
The BDNF note about re-assessment of banked material following a manufacturer-based kit change is another interpretive consideration. The record flags that baseline values differ from published data, but supplies no outcome values or analysis of the measurement change. It is therefore not possible to determine how this issue affected estimates.
The most defensible reading is that the registry captures a planned prospective cohort comparison and its primary measurement schedule, while leaving the findings and their precision unknown. The status is UNKNOWN, and the record lists no analyses. No conclusion about the direction or meaning of a treatment effect is warranted: there was no assigned treatment described, and no outcome effect is posted.
13. Why This Trial Matters Statistically
This study raises a useful statistical distinction between an exposure comparison and a randomized intervention. The study summary asks whether intensive endurance exercise is associated with cognition in older adults, but the registry describes a cohort rather than randomized allocation. That design can document group differences over time, while leaving open whether those differences are attributable to exercise or to other characteristics that distinguish participants.
The matching descriptions make the design question especially relevant. The study summary names age, education years, occupation and verbal intelligence; the control description names age, sex and years of education. These are not identical descriptions, and the record does not clarify how matching was performed or carried through the analysis. Clear reporting of the matched structure and analysis would help readers understand what comparisons the estimates represent.
The primary biomarker is measured at baseline and 5 years, creating a longitudinal question as well as a group comparison. In general, analysis of repeated measures should distinguish change over time from differences between groups and account for the relation between measurements on the same person. The registry does not specify its approach or report results, so those questions remain open.
The assay note is also statistically relevant. Re-assessment of banked material after an analysis-kit change can affect comparability with earlier published values. The record acknowledges the issue but does not provide enough detail to assess its impact. Transparent assay and analysis reporting is important when biomarker levels are compared across studies or time.
Finally, the registry's description of adequate power is not accompanied by a sample-size justification. Planning illustrations based on an observed effect answer a different question from reporting the precision of actual estimates. With no results or confidence intervals, neither the adequacy of the design for its principal comparison nor the informativeness of its findings can be evaluated from this record.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most important limitation of the registry entry is the absence of outcome results. It lists no analyses, estimates, uncertainty intervals or p-values. The stated primary endpoint and follow-up timeframe therefore cannot be used to assess the observed relationship between athlete status and BDNF.
The study is non-randomized, and the registry cautions that the arms are not a like-for-like control comparison. The record does not state an allocation method, does not provide a complete account of eligibility criteria, and truncates the athlete-arm description. The specific training exposure, its duration or intensity, and the degree of variation among athletes are not fully described in the available record.
The matching characteristics are described differently in the study summary and the control-arm text. The record does not state whether matching was individual or group-based, whether it was maintained in analysis, or what adjustment was used. Further information about potential confounding variables is not reported in the registry record.
For the primary outcome, the registry identifies BDNF measured at baseline and 5 years and notes a manufacturer-based assay-kit change affecting re-assessment of banked samples. It does not give assay details, results, or the method used to address the measurement issue. The cognitive measures themselves are not specified in the registry record.
The analysis population, outcome completeness, missing-data handling, multiplicity plan and sample-size justification are not reported in the registry record. The status is UNKNOWN. These omissions limit assessment of study conduct and precision, in addition to preventing interpretation of outcome findings.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Cognitive Function in Elderly Marathon Runners — NCT01045031.
- Registry record last updated 2018-06-26; status last verified 2018-03.
- Results first posted 2016-07-11.
- 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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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes an Austrian prospective cohort study of cognitive function in older marathon runners and bicyclists compared with controls. Medical University of Vienna is listed as sponsor. Enrollment is 114; the listed start is 2008-12 and primary completion is 2014-02. Status is UNKNOWN.
The primary outcome is mean BDNF in ng/mL, measured at baseline and 5 years. The record lists self-rating questionnaires and IGF-1 as secondary outcomes and four outcome measures overall. It notes that baseline BDNF values differ from published data because banked samples were re-assessed following a manufacturer-based analysis-kit change.
The comparison is non-randomized, with differing descriptions of matching characteristics. No analyses or outcome results are listed. The adverse-event record shows zero serious and other events in both groups; deaths are not reported.