Effects of Hydration on Mental and Cognitive Processes in Children and Adults

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2 Effects of Hydration on Mental and Cognitive Processes in Children and Adults Matthew S. Ganio, Ph.D. Assistant Professor of Exercise Science Director, Human Performance Laboratory Department of Health, Human Performance and Recreation University of Arkansas

3 Importance of Hydration & Cognition

4 Outline Defining & measuring hydration status Measuring cognition & mood Effect of hydration on cognition & mood Adults Children Improving hydration

5 TOTAL BODY WATER E X T R F A L C U E I L D L U L A R Plasma 3.0 L CAPILLARY MEMBRANE Interstitial Fluid 11.0 L CELL MEMBRANE INPUT WATER IN FLUIDS AND FOOD OUTPUT KIDNEYS, LUNGS, SKIN, FECES, SWEAT 1/3 Intracellular Fluid 28.0 L 2/3

6 Body Fluid Balance

7 Altered hydration status

8 Delayed Thirst

9 Involuntary Dehydration Drinking as much as sweating Sweating more than drinking

10 How do measure hydration status? Stable isotope dilution Neutron activation analysis Bioelectrical impedance spectroscopy Body mass change Plasma volume change Plasma/Serum osmolality ADH level Urine osmolality Urine specific gravity Urine conductivity Urine color 24-hr urine volume Salivary flow rate Rating of thirst

11 Classifying Hydration Status Adapted from Armstrong 2010 (290 data points, 59 male test subjects). Data fit to normal curve 24-hr fluid intake (L) 24-hr urine volume (L) Morning USG 24-hr USG Morning Urine Osm 24-hr Urine Osm 24-hr Urine Color Extremely hyperhydrated Slightly hyperhydrated >3.3 >2.3 <1.017 <1.012 <545 <377 < Well hydrated Euhydrated Slightly dehydrated Very dehydrated Extremely dehydrated <1.4 <0.9 >1.031 >1.027 >1129 >1013 >6

12 Classifying Hydration Status Adapted from Armstrong 2010 (290 data points, 59 male test subjects). Data fit to normal curve 24-hr fluid intake (L) 24-hr urine volume (L) Morning USG 24-hr USG Morning Urine Osm 24-hr Urine Osm 24-hr Urine Color Extremely hyperhydrated Slightly hyperhydrated >3.3 >2.3 <1.017 <1.012 <545 <377 < Well hydrated Euhydrated Slightly dehydrated Very dehydrated Extremely dehydrated <1.4 <0.9 >1.031 >1.027 >1129 >1013 >6

13 Methods of assessing hydration Nude Body weight pre- and post 70 kg baseline -68 kg after exercise =2 kg 2 / 70 *100 = 2.86 % dehydrated

14 Intermediate Summary There is a constant turnover of water in the body. Stresses to body water balance include ambient temperature and activity level Replacement is not perfect or always timely. Involuntary dehydration In laboratory setting many biological markers can be made If tightly controlled changes in body mass can indicate acute changes in body water loss

15 Outline Defining & measuring hydration status Measuring cognition & mood Effect of hydration on cognition & mood Adults Children Improving hydration

16 What are you measuring? Cognitive Performance Cognitive Effort Mood

17 Cognitive Performance

18 Measuring Cognition F, G, H, J Keys PUT A FINGER OF ONE HAND OVER EACH KEY

19 When the square appears inside, press the appropriate key.

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21 A sample pattern to learn.

22 The correct response.

23 Visual Vigilance

24 Assessing Mood Profile of Mood States

25 Cognitive Effort (Mental Energy) NASA Task Load Index

26 Outline Defining & measuring hydration status Measuring cognition & mood Effect of hydration on cognition & mood Adults Children Improving hydration

27 Hydration and Cognition

28 Cognition & Dehydration? Lieberman 2007

29 Cognition & Hydration Eye-Hand Coordination Sharma 1986

30 Cognition & Hydration Trail Making Task Gopinathan 1988

31 Cognition & Hydration Symbol Substitution Sharma 1986

32 Cognition & Hydration Serial Addition Gopinathan 1988

33 Mood

34 Headache High Fluid restriction Low No fluid restriction 1.0% 1.75% 2.7% Shirreffs et al 2004

35 Ability to Concentrate High No fluid restriction Fluid restriction Low 1.0% 1.75% 2.7% Shirreffs et al 2004

36 Level of Alertness High No fluid restriction Fluid restriction Low 1.0% 1.75% 2.7% Shirreffs et al 2004

37 Hydration and Mood 2.7% dehydration after 24-hr Szinnai et al. 2005

38 Mental Energy Performance not impaired This pattern indicates that participants exerted a higher level of neuronal activity in order to achieve the same performance level Kempton 2010

39 Methodological Factors to Consider

40 Methodological Challenges Cognitive tests employed Sensitivity Specificity Cognate measuring / related measures (e.g., mood) Effect of learning the tests Method of dehydration Exercise Restricting fluid intake Passive heat stress Drugs Confounding Variables Nutritional confounders (e.g., caffeine) Heat stress Body temperature Placebo effect

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42 Methods 26 males; 25 females Healthy, college-aged 3 Trials Dehydration + Diuretic Dehydration + Placebo Euhydration + Placebo

43 Methods Arrival Took Pill (placebo/diuretic) Rest 3 h while urine losses replaced by water ingestion 3 periods of exercise, rest, testing, rest 40 min exercise (5.6 km/hr; 5% grade; 28 C; 42% RH) 20 min rest (fluid ingestion to wet palette or bring to euhydrated state) Minimal Hyperthermia 30 min cognitive test 30 min rest Post-hoc analysis of those that got >1% dehydrated versus euhydrated

44 Results Men (1.59 ± 0.42% hypohydrated) Visual Vigilance errors increased Visual working memory slowed Fatigue Increased Tension/anxiety increased Women (1.36 ± 0.16% hypohydrated) Visual vigilance errors increased Anger-Hostility increased Vigor-Activity decreased Fatigue increased Total mood disturbance increased Task difficulty increased Concentration decreased Headache increased

45 Intermediate Summary Simple tasks requiring less cognitive energy are less affected by dehydration versus complex tasks. Mood state may be more effected by dehydration than cognition. There is not always a link between negative mood and negative cognitive performance. The ability to overcome the negative cognitive effects of dehydration is at the expense of greater mental energy (i.e., greater cognitive effort). The magnitude of dehydration leading to impairments in cognition & mood are largely unknown but may be as little as 1.5% body mass loss.

46 Mild dehydration can affect cognition and mood %

47 Outline Defining & measuring hydration status Measuring cognition & mood Effect of hydration on cognition & mood Adults Children Improving hydration

48 Children, Hydration & Cognition More active=higher fluid needs Lack of hydration knowledge Availability and accessibility may be less Denton 1999

49 Children show up to sports camps dehydrated Evidence that children also often show up to school dehydrated Decher 2008

50 Children in the classroom * 8 years old Extra 300 ml water provided Word recall improved Attention not affected Benton 2009

51 Children in the classroom 6-7 years old Water and No-water group Baseline and post-testing Water group drank ~400 ml Happiness improved Visual attention improved Visual Memory & Search not changed Thirst did not explain differences Changes in happiness did not explain differences Edmonds 2009

52 Children in the classroom years old Hydration measured Number span task (i.e., memorizing sequence of numbers) decreased when dehydrated Bar-David 2005

53 Outline Defining & measuring hydration status Measuring cognition & mood Effect of hydration on cognition & mood Adults Children Improving hydration

54 How do we improve hydration? Educate individuals about hydration What is hydration? Provide starting points for fluid intake Self-assess hydration status Make changes as needed and dependent on situation (e.g., when hot out drink more) Remove barriers to hydration

55 Decher 2008 Hydration Knowledge

56 Decher 2008 Self-Hydration Feedback

57 Feedback on Hydration Status Armstrong, L.E., Maresh, C.M., Castellani, J.W., Bereron, M.F., Kenefick, R.W., LaGassee, K.E., and Riebe, D. (1994). "Urinary Indices of Hydration Status.", Int. J. Sport Nutr., 4,

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59 Access to Fluids Patel et al. 2014

60 Institute of Medicine-Adequate Intake

61 Institute of Medicine-Adequate Intake

62 How much to drink? No accurate recommendation will consistently work within or between individuals Prescribed drinking (i.e., 8 x 8) does not work because different water requirements for individuals Drink to thirst does not work for detecting small changes in hydration status.

63 Long-Term Consequences of Chronic Dehydration? Growing evidence that chronic dehydration has negative physiological consequences Chronic kidney disease Urinary tract infections Kidney stones Do repeated acute detriments in cognition as a result of dehydration have long-term consequences?

64 Thank you Disclosure: Dr. Ganio has been funded by Danone Research Disclosure: and Dr. The Ganio Coca-Cola has been Company funded by Danone Research. Matthew S. Ganio, Ph.D.

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