Stokes AF, Belger A, Banich MT, Taylor H. Effects of acute aspartame and acute alcohol ingestion upon the cognitive performance of pilots. Aviat Space Environ Med. 1991; 62: 648-653.PubMed ID: 1898300
Randomized Controlled Trial
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To determine whether acute dosing with aspartame is in fact associated with cognitive deficits in active pilots, to determine specifically which aspects of aviation-relevant information processing, if any, are affected and to evaluate the sensitivity of the test instrument to performance decrements, due to toxic impairment.
Active pilots possessing a current Class Three Medical Certificate.
- Subjects screened to eliminate any individuals using prescription medication or illicit substances
- Women of childbearing potential, who volunteered, were warned that physicians recommend against the use of alcohol or aspartame during pregnancy.
Description of Study Protocol:
- Pilots recruited
- Two reserve subjects recruited as well
- Methods not specified.
- Randomized controlled trial
- Order of testing was counterbalanced to randomize out any order or learning effects.
The treatment conditions were aspartame, placebo and ethyl alcohol.
- Effects of aspartame and ethanol upon performance were gauged by reference both to inferential statistics and to a normative database provided by a cognitive performance study
- In addition to comparative data, descriptive statistics were completed for each sub-test in the battery
- Repeated-measures ANOVA was performed using the within-subject variable of Session
- Pairwise comparisons were made using Helmert and Reverse Helmert transformations.
Data Collection Summary:
Timing of Measurements
- Subjects were tested over five sessions consisting of pre-test and post-test controls and three randomly ordered treatment sessions
- One week elapsed between sessions.
- SPARTANS cognitive test battery of aviation-relevant information processing tasks, with nine sub-tests relating to perceptual-motor abilities, spatial abilities, working memory, attentional performance in single and dual tasks, risk-taking, processing flexibility, planning and sequencing ability
- Testing was done 45 minutes after consumption.
- Aspartame capsule of 50mg per kg of body weight, ethyl alcohol at 0.1% BAL or placebo capsule taken with fruit juice
- Three-day diet record kept prior to testing sessions
- Subjects refrained from consuming aspartame or alcohol during study.
Description of Actual Data Sample:
- Initial N: 12 volunteers (four females, eight males); two reserve subjects recruited as well
- Attrition (final N): 13 subjects
- Age: Not mentioned
- Ethnicity: Not mentioned
- Other relevant demographics: Not mentioned
- Location: University of Illinois.
Summary of Results:
- Eight variables showed a significant effect of session, traceable in all cases to the effect of alcohol upon performance or to pre- and post-test differences. We were unable to detect any effect of aspartame upon performance in any of the battery sub-tasks.
- No detectable performance decrements were associated with the aspartame condition, although decrements in psychomotor and spatial abilities were detected in the ethanol condition.
Results were found to be consistent with prior flight-simulator studies of alcohol, but there is no evidence in the data that supports the anecdotal evidence regarding the deleterious effects of aspartame upon cognitive performance.
- Small sample size and recruitment methods not specified
- Subjects not well described.
Quality Criteria Checklist: Primary Research
|1.||Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)||Yes|
|2.||Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?||Yes|
|3.||Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?||Yes|
|4.||Is the intervention or procedure feasible? (NA for some epidemiological studies)||Yes|
|1.||Was the research question clearly stated?||Yes|
|1.1.||Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?||Yes|
|1.2.||Was (were) the outcome(s) [dependent variable(s)] clearly indicated?||Yes|
|1.3.||Were the target population and setting specified?||Yes|
|2.||Was the selection of study subjects/patients free from bias?||No|
|2.1.||Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?||Yes|
|2.2.||Were criteria applied equally to all study groups?||Yes|
|2.3.||Were health, demographics, and other characteristics of subjects described?||No|
|2.4.||Were the subjects/patients a representative sample of the relevant population?||???|
|3.||Were study groups comparable?||N/A|
|3.1.||Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)||N/A|
|3.2.||Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?||N/A|
|3.3.||Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)||N/A|
|3.4.||If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?||N/A|
|3.5.||If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)||N/A|
|3.6.||If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?||N/A|
|4.||Was method of handling withdrawals described?||Yes|
|4.1.||Were follow-up methods described and the same for all groups?||Yes|
|4.2.||Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)||Yes|
|4.3.||Were all enrolled subjects/patients (in the original sample) accounted for?||Yes|
|4.4.||Were reasons for withdrawals similar across groups?||N/A|
|4.5.||If diagnostic test, was decision to perform reference test not dependent on results of test under study?||N/A|
|5.||Was blinding used to prevent introduction of bias?||Yes|
|5.1.||In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?||Yes|
|5.2.||Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)||Yes|
|5.3.||In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?||N/A|
|5.4.||In case control study, was case definition explicit and case ascertainment not influenced by exposure status?||N/A|
|5.5.||In diagnostic study, were test results blinded to patient history and other test results?||N/A|
|6.||Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?||Yes|
|6.1.||In RCT or other intervention trial, were protocols described for all regimens studied?||Yes|
|6.2.||In observational study, were interventions, study settings, and clinicians/provider described?||N/A|
|6.3.||Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?||Yes|
|6.4.||Was the amount of exposure and, if relevant, subject/patient compliance measured?||Yes|
|6.5.||Were co-interventions (e.g., ancillary treatments, other therapies) described?||Yes|
|6.6.||Were extra or unplanned treatments described?||Yes|
|6.7.||Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?||Yes|
|6.8.||In diagnostic study, were details of test administration and replication sufficient?||N/A|
|7.||Were outcomes clearly defined and the measurements valid and reliable?||Yes|
|7.1.||Were primary and secondary endpoints described and relevant to the question?||Yes|
|7.2.||Were nutrition measures appropriate to question and outcomes of concern?||Yes|
|7.3.||Was the period of follow-up long enough for important outcome(s) to occur?||Yes|
|7.4.||Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?||Yes|
|7.5.||Was the measurement of effect at an appropriate level of precision?||Yes|
|7.6.||Were other factors accounted for (measured) that could affect outcomes?||Yes|
|7.7.||Were the measurements conducted consistently across groups?||Yes|
|8.||Was the statistical analysis appropriate for the study design and type of outcome indicators?||Yes|
|8.1.||Were statistical analyses adequately described and the results reported appropriately?||Yes|
|8.2.||Were correct statistical tests used and assumptions of test not violated?||Yes|
|8.3.||Were statistics reported with levels of significance and/or confidence intervals?||Yes|
|8.4.||Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?||N/A|
|8.5.||Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?||N/A|
|8.6.||Was clinical significance as well as statistical significance reported?||Yes|
|8.7.||If negative findings, was a power calculation reported to address type 2 error?||N/A|
|9.||Are conclusions supported by results with biases and limitations taken into consideration?||Yes|
|9.1.||Is there a discussion of findings?||Yes|
|9.2.||Are biases and study limitations identified and discussed?||Yes|
|10.||Is bias due to study's funding or sponsorship unlikely?||Yes|
|10.1.||Were sources of funding and investigators' affiliations described?||Yes|
|10.2.||Was the study free from apparent conflict of interest?||Yes|