Doctoral Dissertation Research in Economics: The Cognitive Link between Micronutrient Deficiency in Utero and Schooling Attainment in Tanzania

据估计，发展中国家教育的巨大市场回报刺激了政策对改善学校教育投资的兴趣。尽管影响个人上学决定的因素有很多，但影响学习和受教育程度的另一种重要的、尚未研究的机制是——不良的子宫环境从生物学角度限制了认知发展、学习能力和随后的上学需求。通过实地实验，本项目考察了(1)子宫内微量营养素缺乏（特别是叶酸、维生素B6和维生素B12）对认知和儿童学业的因果影响，以及(2)父母分配资源是否弥补或加强了儿童初始禀赋的不平等。为了解决这两个问题，该研究小组将收集一项个人水平随机试验的后续数据，该试验最初于2001年至2004年在坦桑尼亚达累斯萨拉姆进行，向艾滋病毒孕妇提供营养补充剂。神经科学家已经发现，缺乏四种微量营养素——维生素B6、维生素B9、维生素B12和碘——会对个人的认知能力造成不可逆转的、持续的损害。这个项目关注这些营养物质，因为只有它们在个体的一生中对学习产生持久和持续的影响。个体水平随机化和大样本量使研究小组能够检测到因果关系-à-vis先前的研究。研究小组将使用生物标志物数据，并对儿童进行认知测试，分别代表个人的健康状况和认知发展。特别令人感兴趣的是，微量营养素缺乏在解释坦桑尼亚学校教育结果的性别差异方面可能发挥的作用。该研究旨在促进跨学科和学术机构之间的培训、教学和科学合作。一个由哈佛大学经济系、哈佛大学医学院和坦桑尼亚Muhimbili医学院的经济学家、流行病学家、营养学家和统计学家组成的小组正在开展这个项目。研究完成后，主要研究人员将在跨学科会议上展示结果，并将在经济学、社会科学和医学期刊上发表研究结果。

Large estimated market returns to education in developing countries have stimulated policy interest in improving investments in schooling. Though many factors influence individual schooling decisions, an important and unstudied alternative mechanism influences learning and educational attainment -- poor in utero environment biologically constrains cognitive development, learning capacity and therefore subsequent demand for schooling.Using a field experiment, this project examines (1) the causal impact of micronutrient deficiency (specifically for folic acid, B6 and B12) in utero on cognition and children's schooling, and (2) whether parents allocate resources so as to compensate for or to reinforce inequalities in initial endowments across children. To address these two questions, the research team will collect follow-up data on an individual-level randomized trial of nutritional supplements offered to HIV-pregnant women in Dar es Salaam, Tanzania initially conducted between 2001 and 2004.Neuroscientists have identified that deficiency in four micronutrients -- B6, B9 and B12, and iodine -- results in irreversible and continuous damage to individuals' cognitive capacity. This project focuses on these nutrients because only they exert persistent and continuous effect on learning over the lifespan of individuals. Individual level randomization and a large sample size enable the research team to detect causal effects vis-à-vis previous studies.The research team will use biomarker data and will conduct cognitive tests with children to proxy respectively individuals' health status and cognitive development. Of particular interest is the possible role of micronutrient deficiency in explaining gender differences in schooling outcomes in Tanzania. The study aims to promote training, teaching and scientific collaborations across disciplines and academic institutions. A team comprising of economists, epidemiologists, nutrition scientists, and statisticians from Harvard's Economics Department, The Harvard Medical School and the Tanzania-based Muhimbili Medical School are conducting this project. Upon study completion, the principal investigators will present results in interdisciplinary conferences and will publish findings in economics, social science and medical journals.