Maternal dietary intake of polyunsaturated fatty acids modifies association between prenatal DDT exposure and child neurodevelopment: A cohort study

Prenatal air pollution and children's autism traits score: Examination of joint associations with maternal intake of vitamin D, methyl donors, and polyunsaturated fatty acids using mixture methods

Background

Maternal nutrient intake may moderate associations between environmental exposures and children's neurodevelopmental outcomes, but few studies have assessed joint effects. We aimed to evaluate whether prenatal nutrient intake influences the association between air pollutants and autism-related trait scores.

Methods

We included 126 participants from the EARLI (Early Autism Risk Longitudinal Investigation, 2009-2012) cohort, which followed US pregnant mothers who previously had a child with autism. Bayesian kernel machine regression and traditional regression models were used to examine joint associations of prenatal nutrient intake (vitamins D, B12, and B6; folate, choline, and betaine; and total omega 3 and 6 polyunsaturated fatty acids, reported via food frequency questionnaire), air pollutant exposure (particulate matter <2.5 μm [PM2.5], nitrogen dioxide [NO2], and ozone [O3], estimated at the address level), and children's autism-related traits (measured by the Social Responsiveness Scale [SRS] at 36 months).

Results

Most participants had nutrient intakes and air pollutant exposures that met US standards. Bayesian kernel machine regression mixture models and traditional regression models provided little evidence of individual or joint associations of nutrients and air pollutants with SRS scores or of an association between the overall mixture and SRS scores.

Conclusion

In this cohort with a high familial likelihood of autism, we did not observe evidence of joint associations between air pollution exposures and nutrient intake with autism-related traits. Future work should examine the use of these methods in larger, more diverse samples, as our results may have been influenced by familial liability and/or relatively high nutrient intakes and low air pollutant exposures.

Literature landscape of neurodevelopment and pesticides: A scoping review of methodologies

Pesticides are highly tested and regulated chemicals. There is currently great interest in the role that pesticides may play in childhood neurodevelopment. The objective was to identify and describe the body of evidence and to assess the ability to synthesize effect estimates. The epidemiologic literature from 2011 to 2022 was searched for publications on the association between pesticide exposure and neurodevelopment, behavior, and/or cognition in children. We identified 114 publications, representing 67 unique studies. While organochlorine and other insecticides were the most common classes of pesticides studied, up to 159 different metabolites or active ingredients were reported. Nine pesticides or their metabolites were reported in >10 publications. Similarly, multiple assessment methods were administered across studies to evaluate outcomes in neurodevelopment at ages which ranged from birth to 18 years of age. This scoping review reveals the heterogeneity among published studies with respect to exposures and health outcomes, in the methods used to assess and classify them, and in combinations of the two. This limits the adequacy of the evidence to evaluate specific risk estimates for a particular exposure-outcome pair. Intentional coordination among researchers to increase consistency in methodologies would facilitate the synthesis of results across studies. Research opportunities also exist to validate assumptions in exposure and outcome assessment which are implicit in many of the studies reviewed. In conclusion, there are many ongoing epidemiologic studies with a focus on pesticides and neurodevelopment. The variety of exposures, exposure assessment methods and tests for each outcome can be overwhelming. Interdisciplinary collaboration is recommended to harmonize data collection and to enable meaningful interpretation of the study results across populations.

Pyrethroid and Chlorpyrifos Pesticide Exposure, General Intellectual Abilities, and Executive Functions of School Children from Montevideo, Uruguay

Children's developing brains are susceptible to pesticides. Less is known about the effect of exposure to chlorpyrifos and pyrethroids on executive functions (EF). We measured urinary 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of chlorpyrifos, and urinary 3-phenoxybenzoic acid (3-PBA), a general, nonspecific metabolite of pyrethroids in first-grade children from Montevideo, Uruguay (n = 241, age 80.6 ± 6.4 months, 58.1% boys). EFs were assessed with the Intra-dimensional/Extra-dimensional shift (IED), Spatial Span (SSP), and Stockings of Cambridge (SOC) tests from the Cambridge Neuropsychological Test Automated (CANTAB) Battery. General intellectual ability (GIA) was assessed using the Woodcock-Muñoz Cognitive battery. Median (range) urinary TCPy and 3-PBA levels were 16.7 (1.9, 356.9) ng/mg of creatinine and 3.3 (0.3, 110.6) ng/mg of creatinine, respectively. In multivariable generalized linear models, urinary TCPy was inversely associated with postdimensional errors on the IED task β [95% CI]: -0.11 [-0.17, -0.06]. Urinary 3-PBA was inversely associated with the total number of trials -0.07 [-0.10, -0.04], and the total number of errors -0.12 [-0.18, -0.07] on the IED task. When TCPy and 3-PBA were modeled together, the associations did not differ from single-metabolite models. We found no evidence of effect modification by blood lead level (BLL). Pesticide exposure may affect EF performance in urban children.

Health Effects of Pesticide Exposure in Latin American and the Caribbean Populations: A Scoping Review

BACKGROUND

Multiple epidemiological studies have shown that exposure to pesticides is associated with adverse health outcomes. However, the literature on pesticide-related health effects in the Latin American and the Caribbean (LAC) region, an area of intensive agricultural and residential pesticide use, is sparse. We conducted a scoping review to describe the current state of research on the health effects of pesticide exposure in LAC populations with the goal of identifying knowledge gaps and research capacity building needs.

METHODS

We searched PubMed and SciELO for epidemiological studies on pesticide exposure and human health in LAC populations published between January 2007 and December 2021. We identified 233 publications from 16 countries that met our inclusion criteria and grouped them by health outcome (genotoxicity, neurobehavioral outcomes, placental outcomes and teratogenicity, cancer, thyroid function, reproductive outcomes, birth outcomes and child growth, and others).

RESULTS

Most published studies were conducted in Brazil (37%, n = 88 ) and Mexico (20%, n = 46 ), were cross-sectional in design (72%, n = 167 ), and focused on farmworkers (45%, n = 105 ) or children (21%, n = 48 ). The most frequently studied health effects included genotoxicity (24%, n = 62 ) and neurobehavioral outcomes (21%, n = 54 ), and organophosphate (OP) pesticides were the most frequently examined (26%, n = 81 ). Forty-seven percent (n = 112 ) of the studies relied only on indirect pesticide exposure assessment methods. Exposure to OP pesticides, carbamates, or to multiple pesticide classes was consistently associated with markers of genotoxicity and adverse neurobehavioral outcomes, particularly among children and farmworkers.

DISCUSSION

Our scoping review provides some evidence that exposure to pesticides may adversely impact the health of LAC populations, but methodological limitations and inconsistencies undermine the strength of the conclusions. It is critical to increase capacity building, integrate research initiatives, and conduct more rigorous epidemiological studies in the region to address these limitations, better inform public health surveillance systems, and maximize the impact of research on public policies. https://doi.org/10.1289/EHP9934.

Exposure to DDT and DDE and functional neuroimaging in adolescents from the CHAMACOS cohort

BACKGROUND

Epidemiological studies suggest that exposure to p,p'-dichloro-diphenyl-trichloroethane (p,p'-DDT) is associated with poorer cognitive function in children and adolescents, but the neural mechanisms underlying this association remain unclear.

OBJECTIVE

We investigated associations of prenatal and childhood exposure to p,p'-DDT and its metabolite p,p'-dichloro-diphenyl-dichloroethylene (p,p'-DDE) with cortical activation in adolescents using functional near-infrared spectroscopy (fNIRS).

METHODS

We administered fNIRS to 95 adolescents from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) aged 15-17 years. We assessed cortical activity in the frontal, temporal, and parietal brain regions while participants completed tasks of executive function, language comprehension, and social cognition. We measured serum p,p'-DDT and -DDE concentrations at age 9 years and then estimated exposure-outcome associations using linear regression models adjusted for sociodemographic characteristics. In secondary analyses, we back-extrapolated prenatal concentrations using prediction models and examined their association with cortical activation.

RESULTS

Median (P25-P75) p,p'-DDT and -DDE concentrations in childhood were 1.4 (1-2.3) and 141.5 (75.0-281.3) ng/g lipid, respectively. We found that childhood exposure to p,p'-DDT and -DDE was associated with altered patterns of brain activation during tasks of cognition and executive functions. For example, we observed increased activity in the left frontal lobe during a language comprehension task (β per 10 ng/g lipid increase of serum p,p'-DDE at age 9 years = 3.4; 95% CI: 0.0, 6.9 in the left inferior frontal lobe; and β = 4.2; 95% CI: 0.9, 7.5 in the left superior frontal lobe). We found no sex differences in the associations of childhood p,p'-DDT and -DDE concentrations with neural activity. Associations between prenatal p,p'-DDT and p,p'-DDE concentrations and brain activity were similar to those observed for child p,p'-DDT and -DDE concentrations.

CONCLUSIONS

Childhood p,p'-DDT and -DDE exposure may impact cortical brain activation, which could be an underlying mechanism for its previously reported associations with poorer cognitive function.

Prenatal Diet as a Modifier of Environmental Risk Factors for Autism and Related Neurodevelopmental Outcomes

PURPOSE OF REVIEW

Environmental chemicals and toxins have been associated with increased risk of impaired neurodevelopment and specific conditions like autism spectrum disorder (ASD). Prenatal diet is an individually modifiable factor that may alter associations with such environmental factors. The purpose of this review is to summarize studies examining prenatal dietary factors as potential modifiers of the relationship between environmental exposures and ASD or related neurodevelopmental outcomes.

RECENT FINDINGS

Twelve studies were identified; five examined ASD diagnosis or ASD-related traits as the outcome (age at assessment range: 2-5 years) while the remainder addressed associations with neurodevelopmental scores (age at assessment range: 6 months to 6 years). Most studies focused on folic acid, prenatal vitamins, or omega-3 fatty acids as potentially beneficial effect modifiers. Environmental risk factors examined included air pollutants, endocrine disrupting chemicals, pesticides, and heavy metals. Most studies took place in North America. In 10/12 studies, the prenatal dietary factor under study was identified as a significant modifier, generally attenuating the association between the environmental exposure and ASD or neurodevelopment. Prenatal diet may be a promising target to mitigate adverse effects of environmental exposures on neurodevelopmental outcomes. Further research focused on joint effects is needed that encompasses a broader variety of dietary factors, guided by our understanding of mechanisms linking environmental exposures with neurodevelopment. Future studies should also aim to include diverse populations, utilize advanced methods to optimize detection of novel joint effects, incorporate consideration of timing, and consider both synergistic and antagonistic potential of diet.

COpenhagen Neuroplastic TRaining Against Contractures in Toddlers (CONTRACT): protocol of an open-label randomised clinical trial with blinded assessment for prevention of contractures in infants with high risk of cerebral palsy

INTRODUCTION

Contractures are frequent causes of reduced mobility in children with cerebral palsy (CP) already at the age of 2-3 years. Reduced muscle use and muscle growth have been suggested as key factors in the development of contractures, suggesting that effective early prevention may have to involve stimuli that can facilitate muscle growth before the age of 1 year. The present study protocol was developed to assess the effectiveness of an early multicomponent intervention, CONTRACT, involving family-oriented and supervised home-based training, diet and electrical muscle stimulation directed at facilitating muscle growth and thus reduce the risk of contractures in children at high risk of CP compared with standard care.

METHODS AND ANALYSIS

A two-group, parallel, open-label randomised clinical trial with blinded assessment (n=50) will be conducted. Infants diagnosed with CP or designated at high risk of CP based on abnormal neuroimaging or absent fidgety movement determined as part of General Movement Assessment, age 9-17 weeks corrected age (CA) will be recruited. A balanced 1:1 randomisation will be made by a computer. The intervention will last for 6 months aiming to support parents in providing daily individualised, goal-directed activities and primarily in lower legs that may stimulate their child to move more and increase muscle growth. Guidance and education of the parents regarding the nutritional benefits of docosahexaenic acid (DHA) and vitamin D for the developing brain and muscle growth will be provided. Infants will receive DHA drops as nutritional supplements and neuromuscular stimulation to facilitate muscle growth. The control group will receive standard care as offered by their local hospital or community. Outcome measures will be taken at 9, 12, 18, 24, 36 and 48 months CA. Primary and secondary outcome measure will be lower leg muscle volume and stiffness of the triceps surae musculotendinous unit together with infant motor profile, respectively.

ETHICS AND DISSEMINATION

Full approval from the local ethics committee, Danish Committee System on Health Research Ethics, Region H (H-19041562). Experimental procedures conform with the Declaration of Helsinki.

TRIAL REGISTRATION NUMBER

NCT04250454.

EXPECTED RECRUITMENT PERIOD

1 January 2021-1 January 2025.

Association Between Midpregnancy Polyunsaturated Fatty Acid Levels and Offspring Autism Spectrum Disorder in a California Population-Based Case-Control Study

Polyunsaturated fatty acids (PUFAs) are critical for brain development and have been linked with neurodevelopmental outcomes. We conducted a population-based case-control study in California to examine the association between PUFAs measured in midpregnancy serum samples and autism spectrum disorder (ASD) in offspring. ASD cases (n = 499) were identified through the California Department of Developmental Services and matched to live-birth population controls (n = 502) on birth month, year (2010 or 2011), and sex. Logistic regression models were used to examine crude and adjusted associations. In secondary analyses, we examined ASD with and without co-occurring intellectual disability (ID; n = 67 and n = 432, respectively) and effect modification by sex and ethnicity. No clear patterns emerged, though there was a modest inverse association with the top quartile of linoleic acid level (highest quartile vs. lowest: adjusted odds ratio = 0.74, 95% confidence interval: 0.49, 1.11; P for trend = 0.10). Lower levels of total and ω-3 PUFAs were associated with ASD with ID (lowest decile of total PUFAs vs. deciles 4-7: adjusted odds ratio = 2.78, 95% confidence interval: 1.13, 6.82) but not ASD without ID. We did not observe evidence of effect modification by the factors examined. These findings do not suggest a strong association between midpregnancy PUFA levels and ASD. In further work, researchers should consider associations with ASD with ID and in other time windows.

Exposure to environmental neurotoxic substances and neurodevelopment in children from Latin America and the Caribbean

Environmental (and occupational) exposure to neurotoxic substances is a worldwide problem that can affect children's neurodevelopment (ND). In Latin American and Caribbean (LAC) countries there are over 300 million children living under the threat of neurodevelopmental delays due to toxic environmental exposure. Large industrial centers, intense mining and agricultural activities, along with changing complex ecosystems constitute a mosaic that drives contamination of air, water and the food chain. Neurotoxic contaminants such as pesticides (organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, and manganese fungicides), chemicals of industrial use (phthalates), and metals (Hg, Pb, Al, As, F, Cd, Mo, Mn) are at the center of environmental exposure studies. Exposure to neurotoxic substances singly or in combination with other compounds or socioeconomic stressors (maternal education, socio-economic and nutritional status) intertwined with occupational and para-occupational exposure can affect ND (motor, cognition, behavior) of children. Significant negative effects of pesticides and neurotoxic elements on ND were found in all studied countries, affecting especially the less-privileged children from laboring families. Studies showed that exposures to the neurotoxicants in human milk are secondary to their more lasting effects during prenatal exposure. This review integrates exposure (prenatal and breastfeeding), metabolism, and ND effects of neurotoxicants. It highlights the overwhelming evidence showing that current levels of exposures are hazardous and detrimental to children's ND in LAC countries. The evidence indicates that a reduction in neurotoxicant exposure is essential to protect children's ND. Therefore, it is urgent to adopt policies and actions that prevent and remediate region-specific children's ND issues.

Maternal Dietary Factors and the Risk of Autism Spectrum Disorders: A Systematic Review of Existing Evidence

Prenatal maternal diet is a critical factor in offspring neurodevelopment. Emerging evidence suggests that prenatal diet may also play a role in the etiology autism spectrum disorder (ASD). This review summarizes studies published in English that examined prenatal nutrients or maternal diet in association with ASD from PubMed as of July 2020. Thiry-six studies from nine countries were included in this systematic review; these focused on multivitamin (n = 5), prenatal vitamin (n = 3), folic acid (FA; n = 14), Vitamin D (n = 11), polyunsaturated fatty acid or fish/supplement intake (n = 7), iron (n = 3), Vitamin B12 (n = 1), calcium (n = 1), magnesium (n = 1), and broad maternal dietary habits (n = 3). Overall, higher or moderate intake of prenatal/multivitamin, FA, and Vitamin D was associated with reductions in odds of ASD, though results have not been uniform and there is a need to clarify differences in findings based on biomarkers versus reported intake. Evidence was inconclusive or insufficient for other nutrients. Differences in the timing and measurement of these dietary factors, as well as potential residual confounding, may contribute to existing discrepancies. Key areas for future research to better understand the role of maternal diet in ASD include the need to address potential critical windows, examine the combined effect of multiple nutrients, and consider interactions with genetic or environmental factors. LAY SUMMARY: Maternal diet during pregnancy is important for child neurodevelopment. We reviewed 36 studies examining maternal diet and autism spectrum disorder (ASD) and found that prenatal vitamin/multivitamin use and adequate intake of folic acid and Vitamin D were each associated with lower likelihood of having a child with ASD. Future studies on these and other dietary factors are needed to better understand the role of maternal diet in the development of ASD. Autism Res 2020, 13: 1634-1658. © 2020 International Society for Autism Research and Wiley Periodicals LLC.

Maternal n-3 PUFAs deficiency during pregnancy inhibits neural progenitor cell proliferation in fetal rat cerebral cortex

The aim of this study was to evaluate the in vivo impacts of maternal n-3 polyunsaturated fatty acids (PUFAs) deficiency during pregnancy on the proliferation of neural progenitor cells (NPCs) in the developing cerebral cortex of fetal rats. Our results showed that about 5 weeks of maternal dietary n-3 PUFAs deprivation resulted in a substantial n-3 PUFA deficiency in fetal rat cerebral cortex. Importantly, by two survival schemes and two quantitative methods, we found that maternal intake of n-3 PUFAs deficient diet during the gestation significantly inhibited the proliferation of NPCs in fetal rat cerebral cortex. Moreover, the decreased cortical NPCs proliferation induced by nutritional n-3 PUFAs restriction did not originate from the increased NPCs apoptosis. Finally, our observations indicated that the down-regulation of cyclin E protein might be involved in the inhibitory effects of maternal n-3 PUFAs deficient diet on the proliferation of cortical NPCs. These findings highlight the importance of maternal intake of appropriate n-3 PUFAs and deepen our understanding of the exact effects of n-3 PUFAs on mammalian brain development.

Polyunsaturated fatty acids and child neurodevelopment among a population exposed to DDT: a cohort study

BACKGROUND

Child neurodevelopment has been positively linked to maternal intake of polyunsaturated fatty acids (PUFAs) during pregnancy; however, it is unknown if that relationship persists among populations exposed to environmental neurotoxicants.

OBJECTIVE

The aim of this work was to assess whether maternal dietary intake of PUFAs during pregnancy is positively associated with child neurodevelopment, whose mothers were environmentally exposed to 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT).

METHODS

A prospective cohort study with 276 mother-child pairs was performed in Mexico. Neurodevelopment was assessed by Bayley Scales II from children age 1 to 30 months. Dietary PUFAs intake was estimated by Food Frequency Questionnaire at 1st and 3rd trimester of pregnancy. DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene, the main metabolite of DDT) maternal serum levels were determined by electron capture gas chromatography. Longitudinal multivariate linear mixed-effects analysis, which combines mental (MDI) and motor (PDI) Bayley scales in a single model, were performed.

RESULTS

Our results show that in a sample environmentally exposed to DDT, maternal ingestion of DPA during the first trimester of pregnancy was positively associated with MDI (β = 0.10, 95% CI 0.02, 0.18) in children from 1 to 30 months. Likewise, our results suggest that dietary ALA may be also related to MDI.

CONCLUSION

DPA may benefit neurodevelopment even in populations exposed to DDT. Our results strengthen the importance of PUFAs intake during the prenatal period.