Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853
Performing Department
Nutritional Sciences
Non Technical Summary
This research addresses the problem of establishing accurate choline intake guidelines for pregnant and lactating women so as to enhance the cognitive and affective functioning of their children from infancy through old age. Increasing evidence suggests that current recommendations for maternal choline intake may be insufficient for optimal fetal brain development. Insufficient maternal choline intake is likely to cause (i) a reduction in her child's cognitive abilities throughout life; (ii) an increase in the brain's vulnerability to damage from exposure to many neurotoxins; and (iii) an acceleration of aging-related cognitive dysfunction and increased vulnerability of the brain to various forms of dementia. From a societal perspective, by correcting suboptimal choline intake during pregnancy and lactation it may be possible to substantially reduce the enormous health care costs associated with aging-related cognitive impairments while also increasing the intellectual capital of our citizenry during their most economically productive years. Although several decades of research in animals strongly suggests that these goals can be achieved by increasing maternal intake of choline during pregnancy and lactation, there presently exists no research in a human population that has adequately tested the hypothesis that maternal choline supplementation in humans is similarly beneficial for cognitive and affective functioning in children. Mounting evidence suggests that current maternal choline intake recommendations are insufficient for optimal brain development, cognitive function, and the lifelong health of offspring. First, in rodents consuming normal chow, pregnancy causes a pronounced depletion of maternal choline stores, indicating that choline requirements during pregnancy are increased and that maternal and fetal requirements may commonly exceed the amount consumed by the mother. Second, research from our laboratory indicates a similar depletion of maternal choline stores during human pregnancy, such that, even when pregnant women consume choline at twice the current intake recommendations there is evidence that their physiological needs are unmet. Third, and most importantly, a substantial body of experimental animal research shows that maternal choline supplementation (i) significantly improves memory, attention, and emotional regulation of the offspring; (ii) reduces or eliminates normal age-related decline in cognitive function; and (iii) reduces the impact of a range of prenatal neural insults such as fetal alcohol exposure.Despite extensive experimental data in animal models demonstrating lasting beneficial effects of increased maternal choline intake for offspring, few studies have investigated this phenomenon in humans, and results to date have been equivocal. However, a recent randomized feeding trial from our laboratory demonstrated beneficial effects of increased maternal choline intake (930 mg/day vs. 480 mg/day) on cognition, affect, and stress reactivity of the hypothalamic-pituitary-adrenal axis in young infants. It is currently unknown if these beneficial effects represent only a transient acceleration of cognitive development during the period of infancy or if, as has been observed in research in rodents, the effects of increased prenatal choline reflect a more enduring alteration of brain function that is likely to persist throughout life.The current study addresses this important question by following up the children born to mothers who participated in this trial to examine longer-term effects of maternal choline supplementation on child cognition at six years of age. This will be the first controlled trial of the effects of maternal choline supplementation on cognition, affect, and stress reactivity in school-aged children, a time when neurobehavioral tests predict later cognitive, psychosocial, and academic outcomes, including adult cognitive functioning and socioeconomic success.We will also follow up and test another group of 6-year-old children whose mothers participated in a companion randomized feeding trial during the early postnatal period (first 12 weeks of lactation). Because children can engage in much more complex cognitive functions than infants, we will be able to use more refined tests of specific cognitive and neurobehavioral functions and this may allow us to reveal a previously undetected effect of increased maternal choline intake during the early postpartum period. We hypothesize that these findings will provide compelling evidence that choline intake recommendations for pregnant women should be revised to ensure optimal offspring cognitive function throughout life.Our research methods are based on the experimental design of our initial 12-week controlled feeding trials in which all women were fed a standard diet, but were randomly assigned to receive one of two choline supplements to bring their total daily intake to either 480 mg/day or 930 mg/day. In one of the trials, women participated during the 3rd trimester of pregnancy whereas in the companion trial they participated during the first 12 postnatal weeks (while breastfeeding). The diets were designed and prepared by nutritionists and consumed either in our metabolic research unit or consumed off-site as take-away meals and thus we established excellent control over total nutrient and calorie intake, a key requirement for attributing group differences in child outcome to a difference in the level of maternal choline intake.To test for the effects of early maternal choline intake on later child behavior we have designed a battery of tests that will assess multiple aspects of (i) cognition (memory, attention, verbal and nonverbal intellectual ability) and (ii) emotion regulation and psychosocial function (negative and positive emotionality, including symptoms of depression, opposition and defiance, disordered social relations). Our examination of emotional reactivity will also include a measure of physiological reactivity (saliva cortisol), which will be assessed multiple times to obtain an index of diurnal cortisol regulation and also cortisol reactivity to a stressful cognitive task. We will conduct testing on two consecutive days to ensure that the child does not become fatigued and thus can provide his or her optimal performance.We will compare the average performance of children in our different experimental groups to determine whether higher maternal choline intake has lasting effects on child developmental outcomes. To provide insight on whether the effects of higher maternal choline intake depend on the developmental period of exposure, we will compare separately for the group who received the supplement during the prenatal period and the group who received choline during lactation. Finally, our use of multiple outcomes will allow us to determine whether the effects are specific to particular aspects of cognition, emotion, and physiological regulation.The ultimate goal of this project is to inform national and international health policy about the benefits of optimal maternal choline intake levels during pregnancy and/or lactation. With sufficiently strong results from a study that used a highly controlled experimental design, it is possible that new choline intake recommendations may be enacted. The societal benefits of increased maternal choline intake could be very substantial, including a population-wide shift to improved cognitive function and a population-wide reduction in cognitive dysfunctions caused by exposure to neurotoxins and other threats to brain health that manifest themselves in aging-related cognitive deficits and dementia. These effects would increase the intellectual capital and economic productivity of our citizenry while simultaneously reducing health care expenditures caused by cognitive dysfunction at all stages of life.
Animal Health Component
75%
Research Effort Categories
Basic
25%
Applied
75%
Developmental
0%
Goals / Objectives
Converging evidence suggests that current recommendations for maternal choline intake during pregnancy and/or lactation may be insufficient for optimal offspring brain development, cognitive and affective function, and lifelong health. The major goals of this project are to provide high quality evidence from a randomized controlled feeding study to (1) assess the long term impact of maternal choline supplementation in humans during the prenatal or early postnatal period on cognition, affect, and HPA axis stress reactivity in the children at age 6 years and (2) inform public health policy decisions regarding optimal choline intake requirements during pregnancy and early postnatal life. ObjectivesAssess the long term impact of maternal choline supplementation in humans during the prenatal or early postnatal period on cognition, affect, and HPA axis stress reactivity in the children at age 6-7 years.Locate and contact all former participants of our previous randomized controlled feeding studies and recruit them into the follow-up study.Acquire, install, calibrate and pre-test (1) equipment and test materials for child cognitive assessment battery, (2) parent-report instruments and child evaluation protocols for measuring child temperament and affect, and (3) saliva collection kits and cortisol analysis protocols for assessing child HPA axis functioning. Recruit 10 children and conduct pilot testing of complete assessment protocol.Assess cognition, affect and HPA axis function for all successfully recruited children from prenatal and early postnatal maternal choline supplementation feeding trials.Design and conduct intention-to-treat and exploratory data analyses to assess the impact of increased maternal choline intake on child outcomes.Inform public health policy decisions regarding optimal choline intake requirements during pregnancy and early postnatal life.Publish results in leading medical and nutritional science journals.Report at conferences (do we need to be funded to do this under this project...see above about objectives being achievable with available funding).Disseminate to national and international nutrition and health policy organizations? (IoM, WHO, etc.?)
Project Methods
The general scientific method used for this project is the randomized control trial design of the original maternal choline supplementation study conducted when the children were either third-trimester fetuses or breastfeeding neonates. This original random assignment of participants to choline intakes at either 480 mg/day or 930 mg/day provides the experimental control necessary to draw a causal inference about the differential effect of these two levels of choline intake on child outcomes. The specific methods we will use to characterize child outcomes correspond to our three research objectives, as detailed in the following.Objective 1: To assess the effects of increased maternal choline intake on child memory, attention and general cognitive abilitiesMethods: Memory, attention, and general cognitive abilities will be assessed with (1) a carefully selected set of tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB), (2) a sustained attention task (SAT), and (3) the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-IV), as described below. CANTAB is a sensitive and validated battery of touchscreen tests of cognitive functioning. The selected subtests, Delayed Matching to Sample (DMS), Spatial Working Memory (SWM), and Paired Associates Learning (PAL) assess specific aspects of recognition memory and short-term memory shown to be sensitive to MCS in rodents. Intra-Extra Dimensional Set Shift (IED) measures attentional set formation and attentional flexibility (executive functions) and may be sensitive to the functioning of BFCN projections to pre-frontal cortex. The SAT comprises four versions of a stimulus detection task requiring increasing levels of attentional effort by the addition of visual distractors (dSAT), by varying the location where the target stimulus will appear (SAT-VSL), or by combining distractors with variable target location (dSAT-VSL). The WPPSI-IV is a widely used measure of psychometric intelligence based on the child's accumulated learning and verbal and nonverbal reasoning. It will help to fully characterize general cognitive functioning of children in the cohort, and provide data to elucidate the breadth or specificity of observed lasting effects.Objective 2: To determine the effects of increased maternal choline intake on child temperament, psychosocial, and affective function. Methods: Child temperament and psychosocial, emotional, and affective functioning will be assessed with the Children's Behavior Questionnaire (CBQ) and the Behavior Assessment System for Children (BASC-2), both validated caregiver report measures. The CBQ assesses 15 characteristics of temperament nested within three broad categories: effortful control, negative affectivity, and extraversion/surgency. The BASC-2 characterizes behavioral and emotional functioning with a variety of scales including anxiety, aggression, adaptability, and social skills. Importantly, the BASC-2 measures DSM-IV classifications (e.g., for ADHD symptoms), includes norms based on the current US population, and also provides a scale designed to measure parental reporting bias, important for ensuring data quality.Objective 3: To evaluate the effects of increased maternal choline intake on HPA axis activity and reactivity to stress. Methods: To assess HPA axis activity and reactivity, saliva samples will be collected from children (a) during the testing session and (b) at designated time points throughout the course of the day. Since HPA axis activity shows a distinct and pronounced circadian rhythm, with increasing levels of cortisol in the morning before waking, a sharp increase 30 minutes following waking, and then a gradual decline throughout the day until the onset of sleep, it is critical to take multiple cortisol measurements throughout the course of the day to characterize general HPA axis activity as well as contextualize any measurements of HPA axis reactivity to stress. Saliva samples will be analyzed for cortisol via a commercially available ELISA kit (Salimetrics, State College, PA). HPA axis activity samples will be collected at waking, 30 minutes after waking, immediately before testing, and before sleeping to create a diurnal cortisol curve. HPA axis reactivity samples will be collected 20 minutes following a challenging study task and will be compared to samples immediately before testing to examine increase in cortisol in response to testing stimuli.Statistical Methods, Data Analysis and Interpretation: Data from individual subjects will be submitted to quality checks on a rolling basis by visual and statistical analysis of range, level and spread prior to adding it to a master data base. Our cognitive, behavior rating and physiological measures will generate a diverse array of data types for many dependent variables, and we have extensive experience with the analysis needs appropriate for each.Intention-to-treat analyses: Multi-level mixed models will be used to examine the effects of maternal choline intake group (930 vs. 480 mg/d) on primary and secondary outcomes. Analyses comparing choline intake groups will be conducted separately for the pregnancy cohort and the postpartum cohort, although the analytical approach will be the same. The repeated measures nature of many outcomes will entail the use of basic multilevel mixed models (e.g., to model DMS choice accuracy as a function of delay), whereas particular outcomes will require individual growth curve modeling methods (e.g., to model change in hit rate over time in SAT tasks and to model patterns of intra-day change in cortisol concentrations).Here we outline our planned analysis of the main dependent variable from our primary attention task: Hits in SAT. Hits will be treated as count data using generalized linear mixed model methods assuming a Poisson distribution with a log link function and offset by the log of the count of opportunities to respond. The fixed-effect independent variables will be Group (480 or 930 mg/d), Distraction (absent, present), Signal Location (constant, variable), and Signal Duration (50, 29, 17 ms), and the individual child will be included as a random effect. We will examine all main effects and interactions, but devote particular attention to a priori hypothesis-relevant contrasts. Primary analyses will be followed by plausibility analyses to consider the impact of known risk factors relevant to a given outcome (e.g., birth weight, gestational age, delivery method, pregnancy and delivery complications, maternal education). Reported p-values will be 2-sided, and p<0.05 will be considered significant.Interpretation: Because of the randomized control trial design of our study, from our intention-to-treat analyses we will interpret all statistically significant group differences in cognition, affect, and cortisol concentrations as being caused by the corresponding difference in maternal choline intake during pregnancy or lactation. When children of mothers in the higher choline intake group perform better than those in the lower choline intake group, we will interpret this as a beneficial effect of higher maternal choline intake. Correspondingly, although we have not observed any adverse effects of maternal choline supplementation in our previous study and no other human or animal study has reported adverse effects, our analysis plan specifies 2-sided hypothesis tests and thus should there be a statistically significant result for which children of mothers in the lower choline intake group outperform those from the higher maternal choline intake group, we will interpret this as a possible adverse effect of higher choline intake. However, prior to drawing any final conclusions, we will consider the full constellation of effects produced by our many specific outcome measures.