Bayley Scales of Infant Development III and Mullen Scales of Early Learning in Nutrition and Supplement Studies: A Pilot Systematic Review

44 pages. This submission includes the author's thesis as well as supplemental, labeled respectively.Thiamine (vitamin B1) is a micronutrient essential to both metabolic functioning and development. It helps the body to take energy from the nutrients it takes in. Due to a diet heavily reliant on polished white rice in some areas of the world like Cambodia, deficiency is common. This can affect brain and cognitive development in children and even become a life-threatening medical emergency. A new clinical trial in the design phases aims to test the efficacy of preventing thiamine deficiency at the population level by fortifying salt with thiamine, as is done with iodine. My thesis provided a pilot systematic review to assist in the design of this new clinical trial. The pilot review focused on two neurocognitive tasks, the Bayley Scales of Infant and Toddler Development III (BSID III) and the Mullen Scales of Early Learning (MSEL). I analyzed the available evidence in a pilot subset of published articles regarding the effectiveness of these two tasks for measuring cognitive effects in nutrition studies. Inclusion criteria included nutritional research and neurocognitive studies involving the two tasks that took place in lower- and middle-income countries. The participants were between infancy and age 5, and articles were published between 2013-2023. Of the 657 articles resulting from a search of APA PsyNet and PubMed, twenty-one articles were selected for review, involving 25,486 infant participants. The majority of selected studies showed neurodevelopmental effects using either the MSEL or BSID III. Limitations included a lack of assessment of bias within articles and involvement of just one coder. The results of the pilot review showed that both MSEL and BSID III tasks appear to be sensitive to nutrition-related neuro-cognitive effects in infants and toddlers in lower- and middle-income countries