Effects of Dehydration on Mental and Cognitive Performance

14 dehydration. The subject progressively experienced disorientation on arithmetic ability, short-term memory and vasomotor function when less than 2 of body liquid decreased. Cian et al. 2001 analyzed 7 healthy people in France by exposing them to heat and running on treadmill until their body weight loss reached 2.8. Based on that research, dehydration could affect cognitive ability in short and long terms, perceptive discrimination and subjective estimates of fatigue. Motoric coordination is sensitive to dehydration and could decrease even in mild dehydration less than 1 of body weigh loss. Sarma et al. 1986 and Cian et al. 2000 showed that when the level of dehydration reached 2 then the cognitive ability in short and long terms, motorist coordination, reaction time, perceptive discrimination significantly decreased. A further level of dehydration of 3 could also further affect the cognitive ability. Arithmetic ability and the motorist speed showed significant degradation in the level of 4 of dehydration Gopinathan et al., 1988. Besides that even in the 2 of dehydration, subjects felt exhausted easily Chian et al., 2000. Medium and severe dehydration determine cognitive function through intracellular, extra cellular and intravascular volume depletion Wilson Morley, 2003. Moreover, the hormonal and cellular approach is suggested to explain the relationships between dehydration effects towards cognitive performance. It is because the complicated mechanism of neurobiological which affect cognitive ability. Normally water homeostatic can be managed by our body automatically if there is an imbalance situation that interrupted the stability of body fluid. In sever accident or in a merge disorientation cases, an excessive respond of homeostatic can induces physiologic disorder. This condition is described by cellular responds to dehydration in molecular level through intracellular calcium accumulation which trigger nerve inactivation. Even though study reports still inconclusively stated but there are a tendency that dehydration status could elevate cortisol serum hypercortisolemia. This is relevant with the hypothesis of cognitive disorientation because medium dehydration can be caused by cortisol hormone. Study in animal assay showed that even though hypercortisolemia seemed not to affect the passive learning but there were a tendency to reduce active learning ability and short term memory. Wilson and Morley 2003 explained that the study of cellular network found the possibility of the role of Arginin Vasopressin Perifer AVP into cognitive disorientation related to dehydration. Study in animal assay, cellular and hystochemical has shown the indication of nitrite oxide NOS as a mediator on managing the body liquid balance 15 through the mechanism of central homeostatic. Recently, NOS is being considered as important neurotransmitter molecules because it’s existence in all parts of the brain and holds an important role as a retrograde messenger factor in facilitate the long term memory. Animal assay study report has supported the NOS function as a central diffusible messenger in facilitating learning process and memory. It is explained further that the cellular study has shown that glutamate hyper transition related closely with cellular dehydration and reduce cellular energetic. The isolated cell research showed that cell dehydration increase protein catabolism that release amino acid in the cell. The increasing of glutamine release in the cell which occurs when cell dehydrate and the intracellular glutamine concentration decrease when injure. Dehydration effect to cytokine as a cognitive ability medium still has not been clear. Tumor necrosis factor TNF and interleukin-1 IL-1 as a mediator of acute phase respond towards high temperature dehydration still inconsistently showed its role. Study in animal assay has identified TNF receptor in the brain and nerve connection of IL-1 in mice hypothalamus. Mice atrocities also produce TNF in vivo. Cognitive function has sensitive respond toward dehydration because it can easily disorientate when lack of water. Brain is a reticular activating system that control the awareness and attentiveness, autonomic structure that manage psychomotor function, adjustment metabolism, cortisol structure and mid-brain which control to the ability to analyze, memory and perception. The increasing state of dehydration can further increase brain disorientation. This condition not only affect the cognitive function but also task processing, reduce function and at the end the lower quality of life. 16 METHOD

3.1. Design and Location

A cross sectional study design was applied for this survey. Considering the different temperature or climate ecological area will influence the water intake, two study sites will be chosen, namely: 1 West Bandung, close to Lembang a highland area with 700-1050 m above sea level, which reflects a medium temperature or daily temperature is about 22 o C; and 2 North Jakarta a low land area with 5-50 m above sea level, which reflects a high temperature daily temperature is about 28 o C. This study conducted at 13 - 31 October 2008.

3.2. Sampling

As mention in the background, teenagers and adults 15-24 years are more likely to be a vulnerable group. Therefore, the subject for this study is teenagers males and females, aged 15-18 years from each of the two study sites. Inclusion criteria of this study are 1 adolescent 15 – 18 year and adult 25 – 50 year, 2 spent most of the time in the study site, 3 healthy. Exclusion criteria of the study are 1 not suffering kidney diseases, 2 diabetic, 3 liver diseases. Exclusion criteria determine by medical doctor and urine analysis. The minimum subject size for each study site was calculated based on a minimum subject formula for a cross sectional study design by considering the proportion of dehydration 30 Manz and Wentz, 2005 as follows: n ≥ z α 2 x p 1 – pd 2 n = minimum subject size z α 2 = 1,96 p = 0,3 or 30 Manz and Wentz, 2005 d = estimation accuracy 0,1 Based on above formula, the minimum subject size for each sex group and for each study site is 41 or rounded into 50 people for each age-sex groups. Since there are two sex groups and two age groups and two study sites, the total number of subject is 50 x 2 sex groups x 2 age groups x 2 sites, which is equal to 400 persons. Considering most of this age group 15-18 years is studying at the high schools, the way to select the subject will be technically and economically feasible through 3. 17 selecting the high schools and higher education in each of the study sites West Bandung and North Jakarta. This study also covers the adult subjects. Subjects for adults are the teachers and parents of the school students aged 25-50 years of the two study sites: Figure 1. Scheme of sampling procedure List of SelectedTeachers and School Stafs List of Senior High School in North JakartaWest Bandung List of School appropriate with criteria Selected school 2 schoolslocation List of First Grade Class met the criterias List of Second Grade Class met the criterias List of Third Grade Class met the criterias Selected First Grade Class Selected Second Grade Class Selected Third Grade Class List of students met the criterias malefemale List of students met the criterias malefemale List of students met the criterias malefemale List of Selected Student malefemale List of Selected Student malefemale List of Selected Student malefemale List of Teachers and School Stafs List of Teachers and School Stafs met the criterias