Caroline J. Edmonds

Should children drink more water?: The effects of drinking water on cognition in children

While dehydration has well-documented negative effects on adult cognition, there is little research on hydration and cognitive performance in children. We investigated whether having a drink of water improved childrens performance on cognitive tasks. Fifty-eight children aged 7-9 years old were randomly allocated to a group that received additional water or a group that did not. Results showed that children who drank additional water rated themselves as significantly less thirsty than the comparison group (p=0.002), and they performed better on visual attention tasks (letter cancellation, p=0.02; spot the difference memory tasks, ps=0.019 and 0.014).

Aluminum Exposure From Parenteral Nutrition in Preterm Infants: Bone Health at 15-Year Follow-up

OBJECTIVE: Aluminum has known neurotoxicity and may impair short-term bone health. In a randomized trial, we showed reduced neurodevelopmental scores in preterm infants who were previously exposed to aluminum from parenteral nutrition solutions. Here, in the same cohort, we test the hypothesis that neonatal aluminum exposure also adversely affects long-term bone health, as indicated by reduced bone mass. METHODS: Bone area (BA) and bone mineral content (BMC) of lumbar spine, hip, and whole body were measured with dual radiograph absorptiometry in 13- to 15-year-olds who were born preterm and randomly assigned standard or aluminum-depleted parenteral nutrition solutions during the neonatal period. RESULTS: Fifty-nine children (32% of survivors) were followed. Those who were randomly assigned to standard parenteral nutrition solution had lower lumbar spine BMC, apparently explained by a concomitant decrease in bone size. In nonrandomized analyses, children who were exposed to neonatal aluminum intakes above the median (55 μg/kg) had lower hip BMC (by 7.6% [95% confidence interval 0.21–13.8]; P = 0.02), independent of bone (or body) size. CONCLUSIONS: Neonates who are exposed to parenteral aluminum may have reduced lumbar spine and hip bone mass during adolescence, potential risk factors for later osteoporosis and hip fracture. These findings need confirmation in larger, more detailed studies. Nevertheless, given our previous finding of adverse developmental outcome in these individuals and the sizeable number of contemporary infants who undergo intensive neonatal care and are still exposed to aluminum via parenteral feeding solutions, the potential adverse long-term consequences of early aluminum exposure now deserve renewed attention.

Does having a drink help you think? 6-7-Year-old children show improvements in cognitive performance from baseline to test after having a drink of water.

Little research has examined the effect of water consumption on cognition in children. We examined whether drinking water improves performance from baseline to test in twenty-three 6-7-year-old children. There were significant interactions between time of test and water group (water/no water), with improvements in the water group on thirst and happiness ratings, visual attention and visual search, but not visual memory or visuomotor performance. These results indicate that even under conditions of mild dehydration, not as a result of exercise, intentional water deprivation or heat exposure, childrens cognitive performance can be improved by having a drink of water.

Cortical anomalies associated with visuospatial processing deficits.

Children born preterm provide a fruitful population for studying structure–function relationships because they often have specific functional deficits in the context of normal neurological status. We selected a group of preterm adolescents with deficits in judgment of line orientation. Despite their very low birth weight, all were neurologically normal with no consistent abnormalities on conventional magnetic resonance imaging. However, voxel‐based morphometric analysis of their magnetic resonance imaging scans showed areas of decreased gray matter and increased white matter most prominently in right ventral extrastriate cortex, close to an area previously implicated in the line orientation task. We suggest that these anomalies of cortical architecture relate to impaired performance on the line orientation task. Ann Neurol 2003;53:768–773

The Effect of Intrauterine Growth on Verbal IQ Scores in Childhood: A Study of Monozygotic Twins

OBJECTIVE: Given the adverse neurobiological effects of suboptimal nutrition on the developing brain, it is of social and medical importance to determine if the global prevalence of poor intrauterine growth causes lasting cognitive deficits. We examined whether suboptimal intrauterine growth relates to impaired cognitive outcome by comparing birth weight and cognition in monozygotic twins and considered whether children within-pair differences in birth weight were related to within-pair differences in IQ scores. METHODS: A total of 71 monozygotic twin pairs (aged 7 years 11 months to 17 years 3 months) participated. The Wechsler Intelligence Scale for Children, Third Edition, was administered, and verbal IQ (VIQ) and performance IQ (PIQ) scores were calculated. Regression was used to relate within-pair differences in birth weight to within-pair differences in IQ scores. RESULTS: VIQ but not PIQ score was affected by prenatal growth restriction. The results suggest that the mean advantage for heavier twins relative to their lighter co-twins can be as much as half an SD in VIQ points. In pairs with minimal discordance, heavier twins had lower VIQ scores than their lighter co-twins. CONCLUSIONS: Our study results suggest that lower birth weight in monozygotic twins can also have a negative long-term impact on cognition both in infants who are small at birth and also those with birth weights across the spectrum. Studying monozygotic twins enabled us to examine the effect of reduced intrauterine growth on cognition independently of confounding factors, including parental IQ and education and infant gender, age, genetic characteristics, and gestation.

Aluminium exposure from parenteral nutrition in preterm infants and later health outcomes during childhood and adolescence.

Aluminium is the most common metallic element, but has no known biological role. It accumulates in the body when protective gastrointestinal mechanisms are bypassed, renal function is impaired, or exposure is high - all of which apply frequently to preterm infants. Recognised clinical manifestations of aluminium toxicity include dementia, anaemia and bone disease. Parenteral nutrition (PN) solutions are liable to contamination with aluminium, particularly from acidic solutions in glass vials, notably calcium gluconate. When fed parenterally, infants retain >75% of the aluminium, with high serum, urine and tissue levels. Later health effects of neonatal intravenous aluminium exposure were investigated in a randomised trial comparing standard PN solutions with solutions specially sourced for low aluminium content. Preterm infants exposed for >10 d to standard solutions had impaired neurologic development at 18 months. At 13-15 years, subjects randomised to standard PN had lower lumbar spine bone mass; and, in non-randomised analyses, those with neonatal aluminium intake above the median had lower hip bone mass. Given the sizeable number of infants undergoing intensive care and still exposed to aluminium via PN, these findings have contemporary relevance. Until recently, little progress had been made on reducing aluminium exposure, and meeting Food and Drug Administration recommendations (<5 μg/kg per d) has been impossible in patients <50 kg using available products. Recent advice from the UK Medicines and Healthcare regulatory Authority that calcium gluconate in small volume glass containers should not be used for repeated treatment in children <18 years, including preparation of PN, is an important step towards addressing this problem.

Water consumption, not expectancies about water consumption, affects cognitive performance in adults

Research has shown that water supplementation positively affects cognitive performance in children and adults. The present study considered whether this could be a result of expectancies that individuals have about the effects of water on cognition. Forty-seven participants were recruited and told the study was examining the effects of repeated testing on cognitive performance. They were assigned either to a condition in which positive expectancies about the effects of drinking water were induced, or a control condition in which no expectancies were induced. Within these groups, approximately half were given a drink of water, while the remainder were not. Performance on a thirst scale, letter cancellation, digit span forwards and backwards and a simple reaction time task was assessed at baseline (before the drink) and 20 min and 40 min after water consumption. Effects of water, but not expectancy, were found on subjective thirst ratings and letter cancellation task performance, but not on digit span or reaction time. This suggests that water consumption effects on letter cancellation are due to the physiological effects of water, rather than expectancies about the effects of drinking water.

Empathic and non-empathic routes to visuospatial perspective-taking.

The present study examined whether strategy moderated the relationship between visuospatial perspective-taking and empathy. Participants (N=96) undertook both a perspective-taking task requiring speeded spatial judgements made from the perspective of an observed figure and the Empathy Quotient questionnaire, a measure of trait empathy. Perspective-taking performance was found to be related to empathy in that more empathic individuals showed facilitated performance particularly for figures sharing their own spatial orientation. This relationship was restricted to participants that reported perspective-taking by mentally transforming their spatial orientation to align with that of the figure; it was absent in those adopting an alternative strategy of transposing left and right whenever confronted with a front-view figure. Our finding that strategy moderates the relationship between empathy and visuospatial perspective-taking enables a reconciliation of the apparently inconclusive findings of previous studies and provides evidence for functionally dissociable empathic and non-empathic routes to visuospatial perspective-taking.

Subjective thirst moderates changes in speed of responding associated with water consumption

Participants (N = 34) undertook a CANTAB battery on two separate occasions after fasting and abstaining from fluid intake since the previous evening. On one occasion they were offered 500 ml water shortly before testing, and on the other occasion no water was consumed prior to testing. Reaction times, as measured by Simple Reaction Time (SRT), were faster on the occasion on which they consumed water. Furthermore, subjective thirst was found to moderate the effect of water consumption on speed of responding. Response latencies in the SRT task were greater under the “no water” condition than under the “water” condition, but only for those participants with relatively high subjective thirst after abstaining from fluid intake overnight. For those participants with relatively low subjective thirst, latencies were unaffected by water consumption, and were similarly fast as those recorded for thirsty participants who had consumed water. These results reveal the novel finding that subjective thirst moderates the positive effect of fluid consumption on speed of responding. The results also showed evidence that practice also affected task performance. These results imply that, for speed of responding at least, the positive effects of water supplementation may result from an attenuation of the central processing resources consumed by the subjective sensation of thirst that otherwise impair the execution of speeded cognitive processes.

Generating inferences from written and spoken language: A comparison of children with visual impairment and children with sight

The two experiments reported here investigated the ability of sighted children and children with visual impairment to comprehend text and, in particular, to draw inferences both while reading and while listening. Children were assigned into ‘comprehension skill’ groups, depending on the degree to which their reading comprehension skill was in line with that predicted by their decoding skill. They then read (either print or Braille) and listened to a series of novel short stories. These were followed by a series of questions, which required either the generation of inferences, or an answer that could be taken literally from the text. The results suggest that children with and without sight are comparable in their ability to draw inferences, and that children with visual impairment show an advantage for literal questions under auditory presentation.