Manganese (Mn) is both an essential micronutrient and potential neurotoxicant. This dual role underlies a growing body of literature demonstrating that Mn exhibits a biphasic dose-response relationship with neurocognitive outcomes. We reviewed recent epidemiologic studies from 2007–2016 that investigated the relationship between Mn exposure and cognitive outcomes across the lifespan: early life, school-aged children, and adulthood. In total, 27 research articles were included in this review: 12 pediatric and 15 adult studies (10 occupational and five environmental exposures). The majority of these studies provided evidence of the negative effects of Mn exposure on cognition. The pediatric literature provides evidence that both high and low levels of Mn are negatively associated with intellectual development. Future Mn research should include examination of non-linear relationships and multiple neurotoxicants across the lifespan, and particularly during critical developmental windows.

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Fish oil contains omega-3 fatty acids, which play a vital role in fetal growth and development. In utero exposure to omega-3 fatty acids is exclusively dependent on maternal nutrition. Previous studies have suggested that prenatal fish oil supplementation has positive impacts on child neurodevelopment later in life. This study examines the associations between fish oil supplementation both before pregnancy and throughout pregnancy and subsequent child development. Mother-child pairs from the Upstate KIDS Study, a birth cohort consisting of children born between 2008 and 2010, were included. Self-reported prenatal fish oil supplementation data was available for 5,845 children (3807 singletons and 2038 twins). At multiple time points, from 4 months to 3 years of age, child development was reported by the parents on the Ages and Stages Questionnaire (ASQ). Five developmental domains were assessed: fine motor, gross motor, communication, personal-social and problem solving. Generalized linear mixed models were used to estimate odds ratios (OR) while adjusting for covariates. Primary analyses showed that the risk of failing the ASQ problem solving domain was significantly lower among children of women who took fish oil before pregnancy (OR 0.40, 95% CI: 0.18 – 0.89) and during pregnancy (OR 0.43, 95% CI: 0.22 – 0.83). Gender interaction was not statistically significant although stratified results indicated stronger associations among girls. Similarly, associations were primarily among singletons. Prenatal fish oil supplementation may be beneficial in regards to neurodevelopment. Specifically, it is associated with a lower risk of failing the problem solving domain up to 3 years of age.

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