Please select the eligibility criteria that correspond to the clinical trial below.
Title: Cognitive Effects of Drinking Water and Improving Hydration Status Among Schoolchildren in Zambia
Brief Summary: There is a large body of evidence from adult populations suggesting cognition in adults is affected by hydration status. The few studies conducted in the global North in populations of schoolchildren indicate that drinking water has an impact on pupil performance on basic cognitive tasks. No studies assessing the impact of dehydration and cognition in schoolchildren have been published in the global South, where access to water is the poorest and dehydration prevalence is likely higher. Our group previously carried out research on this topic in Mali, and will build upon findings from that work with this trial. This study will examine the effect of drinking supplementary water during the school day on hydration status and on cognitive test scores in schoolchildren in Zambia.

The investigators hypothesize that providing supplemental water will result in a decrease in prevalence of dehydration in the study group and will result in an improved performance on cognitive test scores.

Data will be collected from up to four purposively-selected schools in the region of Zambia where this study is taking place, from up to a total of 400 children. At each school pupils in grades 3-6 will be eligible for recruitment, dependent upon their understanding of research instructions. Research staff will explain the study to pupils at the school and individually request informed oral assent for participation. A waiver of parental consent for pupil interviews will be secured from the Ministry of Education. At each school, school directors will be asked to sign in loco parentis ("in the place of parent") on behalf of the pupil participants.

Children that assent to participate in the study will be randomly allocated to the intervention or control group. In the intervention group, study participants will receive supplementary water in the morning. In the control group, study participants will receive supplementary water in the afternoon. Testing procedures in both groups is identical and will include a five-minute interview, two cognitive testing sessions of 45 minutes each, and collection of two urine samples during the day. None of these activities collect personal data or identifiers, and the urine sample will not be stored.

All data collection will occur at the school and will be conducted by trained local enumerators. There are no risks to participation other than a small amount of class time missed by pupils, and great efforts will be made to minimize time outside of class.


Options:
A: Inclusion Criteria:

* Attend a school pre-selected for the study
* Attend grade level 3-6
* Understand and respond to verbal instruction

Exclusion Criteria:

* Unable to write down a string of numbers
B: Inclusion Criteria:

* All children in 2nd and 3rd grade of selected elementary schools

Exclusion Criteria:

* parental consent
C: Inclusion Criteria:

* Age between 20-50 years;
* BMI between 28-36 kg/m2;
* Weight stabile 3 months prior to the study inclusion;
* Less than 10 hours of weekly exercise

Exclusion Criteria:

* Diabetes
* Allergic to phenylalanine or milk
* Smoking
* Pregnancy or breast-feeding
D: Inclusion Criteria:

* 12 years to 15 years old
* iso BMI larger than 25
* habitual milk intake less than 250 ml/day
* non-smoker
* healthy at the time of inclusion

Exclusion Criteria:

* chronic illnesses
* intake of antibiotic 1 mo before start of intervention

Answer: A