Cognition - Other
Conditions
Brief summary
Major aim of this study is to add scientifically proven insights into cognitive effects of meals to the existing recommendations for school meals in Germany. As a first step the short-term effects of skipping lunch on children's cognitive functioning in the afternoon will be examined in a cross-over trial. The study is conducted in a large comprehensive school in Gelsenkirchen (Germany) including about 150 children.
Detailed description
Because of cerebral particularities, children may react sensitive to short-term variations of nutrient supply. Therefore, an optimised composition of meals at nutritionally favourable mealtime should be considered for optimal cognitive performance. The increasing implementation of all-day schools in Germany requires the children's catering at school. However, also the number of 'meal skippers' is increasing among children. Thus, the effect of skipping of the midday meal at school on cognitive functioning is examined in this experimental cross-over trial. As prior intake of food can have an influence on the physiological effect of test meal, the children's dietary intake in the morning is standardized. The intervention is integrated in the usual everyday school life: 9.15 a.m. standardized snack within the frame of the regular break, 9.45 a.m. to 12.25 p.m. everyday school life, 12.25 p.m. either lunch (control) or only a non-caloric beverage (intervention of 'skipping meal'), 12.45 p.m. to 1.15 p.m. regular lunch break, 1.15 p.m. computerized tests of cognitive functioning, 2 p.m. lunch for the 'skipping meal'-group. Parameters of cognition with relevance to everyday school life are measured by a computerized test battery of the 'Wiener Testsystem'. Usual eating behaviour, sleep behaviour, physical activity, parental education and migration background are determined as control variables by questionnaires for children, parents and teachers. Beside the Body Mass Index, the individual IQ is measured by a paper-pencil-test.
Interventions
OTHERSkipping lunch
Just water.
Sponsors
Research Institute of Child Nutrition, Dortmund
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
10 Years to 15 Years
Healthy volunteers
Yes
Inclusion criteria
* All sixth grade students of Gesamtschule Berger Feld with the consent of parents and child
Exclusion criteria
* Metabolic diseases or special diet
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Number Correct Reactions | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Number of correct reactions |
| Incorrect Reactions | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Number of incorrect reactions |
| Tonic Alertness (Mean Reaction Time) | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Mean reaction time to response to a simple visual stimulus without a preceding warning signal |
| Tonic Alertness (Deviation of Reaction Time) | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Deviation of reaction time --\> logarithmic standard deviation of the reaction times |
| Tonic Alertness (Commission Errors) | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Reactions when no stimulus had been presented |
| Tonic Alertness (Omission Errors) | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Stimuli to which no reaction follows within 1.5s |
| Immediate Block Span | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Longest sequence correctly reproduced in at least two of three items (the test is a task of reproducing prescribed sequences from two to eight blocks) |
| Incorrect Immediate Block Span | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Number of sequences incorrectly reproduced |
| Correct Immediate Block Span | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Number of sequences correctly reproduced |
| Sequencing Errors | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Sequences including all the blocks of a prescribed sequence, but in the wrong order |
| Reactions | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Number of total reactions (Subjects have to decide whether a displayed figure is identical with one of four figures shown or not) |
| Percentage Incorrect Reactions | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Percentage of incorrect reactions |
| Mean Time Correct Reactions | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Mean time to react correctly |
| Mean Time Incorrect Reactions | Participants were tested twice with one week wash out (1h after having/skipping lunch) | Mean time to react incorrectly |
Participant flow
Recruitment details
Participants recruited from a secondary all-day school in Gelsenkirchen, Germany in May 2011
Pre-assignment details
161 participants were assessed for eligibility; 40 children refused to participate; thus 121 children started the study; one-week wash out;
Participants by arm
| Arm | Count |
|---|---|
| Having Lunch Lunch ad libitum (pasta Bolognese, apple and water) | 66 |
| Skipping Lunch No lunch (water) | 55 |
| Total | 121 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| First Test Day | Learning disabilities; illness | 1 | 10 |
| Second Test Day | illness | 0 | 5 |
Baseline characteristics
| Characteristic | Skipping Lunch | Having Lunch | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 55 Participants | 66 Participants | 121 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 0 Participants | 0 Participants | 0 Participants |
| Age Continuous | 12.7 years STANDARD_DEVIATION 0.6 | 12.7 years STANDARD_DEVIATION 0.6 | 12.7 years STANDARD_DEVIATION 0.6 |
| Region of Enrollment Germany | 55 participants | 66 participants | 121 participants |
| Sex: Female, Male Female | 32 Participants | 32 Participants | 64 Participants |
| Sex: Female, Male Male | 23 Participants | 34 Participants | 57 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 105 | 0 / 105 |
| serious Total, serious adverse events | 0 / 105 | 0 / 105 |
Outcome results
Primary
Correct Immediate Block Span
Number of sequences correctly reproduced
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Correct Immediate Block Span | 10 Sequences correctly reproduced |
| Skipping Lunch | Correct Immediate Block Span | 10 Sequences correctly reproduced |
p-value: 0.33Generalized linear models
Primary
Immediate Block Span
Longest sequence correctly reproduced in at least two of three items (the test is a task of reproducing prescribed sequences from two to eight blocks)
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Immediate Block Span | 5 Longest sequence correctly reproduced |
| Skipping Lunch | Immediate Block Span | 5 Longest sequence correctly reproduced |
p-value: 0.25Generalized linear models
Primary
Incorrect Immediate Block Span
Number of sequences incorrectly reproduced
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Incorrect Immediate Block Span | 2 Sequences incorrectly reproduced |
| Skipping Lunch | Incorrect Immediate Block Span | 2 Sequences incorrectly reproduced |
p-value: 0.7Generalized linear models
Primary
Incorrect Reactions
Number of incorrect reactions
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Incorrect Reactions | 30 Incorrect reactions |
| Skipping Lunch | Incorrect Reactions | 35 Incorrect reactions |
p-value: 0.13Wilcoxon (Mann-Whitney)
Primary
Mean Time Correct Reactions
Mean time to react correctly
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Mean Time Correct Reactions | 0.6 Seconds |
| Skipping Lunch | Mean Time Correct Reactions | 0.6 Seconds |
p-value: 0.68Wilcoxon (Mann-Whitney)
Primary
Mean Time Incorrect Reactions
Mean time to react incorrectly
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Mean Time Incorrect Reactions | 0.5 Seconds |
| Skipping Lunch | Mean Time Incorrect Reactions | 0.5 Seconds |
p-value: 0.67Wilcoxon (Mann-Whitney)
Primary
Number Correct Reactions
Number of correct reactions
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Number Correct Reactions | 586 Correct reactions |
| Skipping Lunch | Number Correct Reactions | 594 Correct reactions |
p-value: 0.45t-test, 2 sided
Primary
Percentage Incorrect Reactions
Percentage of incorrect reactions
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Percentage Incorrect Reactions | 4.7 Incorrect reactions % |
| Skipping Lunch | Percentage Incorrect Reactions | 5.3 Incorrect reactions % |
p-value: 0.11Wilcoxon (Mann-Whitney)
Primary
Reactions
Number of total reactions (Subjects have to decide whether a displayed figure is identical with one of four figures shown or not)
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Reactions | 628 Total reactions |
| Skipping Lunch | Reactions | 638 Total reactions |
p-value: 0.62Wilcoxon (Mann-Whitney)
Primary
Sequencing Errors
Sequences including all the blocks of a prescribed sequence, but in the wrong order
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Sequencing Errors | 2 Sequences with wrong order |
| Skipping Lunch | Sequencing Errors | 2 Sequences with wrong order |
p-value: 0.63Generalized linear models
Primary
Tonic Alertness (Commission Errors)
Reactions when no stimulus had been presented
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Tonic Alertness (Commission Errors) | 2 Commission errors |
| Skipping Lunch | Tonic Alertness (Commission Errors) | 2 Commission errors |
p-value: 0.61Wilcoxon (Mann-Whitney)
Primary
Tonic Alertness (Deviation of Reaction Time)
Deviation of reaction time --\> logarithmic standard deviation of the reaction times
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Tonic Alertness (Deviation of Reaction Time) | 77 Unitless |
| Skipping Lunch | Tonic Alertness (Deviation of Reaction Time) | 84 Unitless |
p-value: 0.07Wilcoxon (Mann-Whitney)
Primary
Tonic Alertness (Mean Reaction Time)
Mean reaction time to response to a simple visual stimulus without a preceding warning signal
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Tonic Alertness (Mean Reaction Time) | 281 Milliseconds |
| Skipping Lunch | Tonic Alertness (Mean Reaction Time) | 279 Milliseconds |
Comparison: Power calculation had been performed.p-value: 0.79Wilcoxon (Mann-Whitney)
Primary
Tonic Alertness (Omission Errors)
Stimuli to which no reaction follows within 1.5s
Time frame: Participants were tested twice with one week wash out (1h after having/skipping lunch)
Population: Complete case analysis
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Having Lunch | Tonic Alertness (Omission Errors) | 0 Omission errors |
| Skipping Lunch | Tonic Alertness (Omission Errors) | 0 Omission errors |
p-value: 0.03Wilcoxon (Mann-Whitney)