Sandra Martínez-Medina

Social cognition begins with the perception of socially relevant information conveyed through others' eyes and faces. Epidemiological studies of social cognition have relied primarily on caregiver- and self-reported measures, which may not capture subtle alterations in the biological processes underlying social cognition. In this pilot study, we used eye-tracking as an objective measure of spontaneous gaze behavior to examine associations between prenatal metal mixture exposure and social perception, an early component of social cognition, during adolescence. Thirty-nine adolescents (median age 13.1 years [8.4–15.3], 51% female) completed a naturalistic eye-tracking paradigm of short videos showing peer-to-peer social interactions. Dynamic areas of interest were drawn around characters' eyes, and gaze fixation duration was recorded using a Tobii Pro Fusion eye tracker. Generalized weighted quantile sum (gWQS) regression was used to examine associations between participants’ prenatal exposure to a mixture of copper (Cu), manganese (Mn), lead (Pb), and zinc (Zn) and fixation duration to the eyes, as well as questionnaire-based measures of social cognition. Higher prenatal metal mixture exposure, driven primarily by Mn (39%), was significantly associated with reduced fixation to the eyes (β = -24.8, 95% CI [-46.4, -3.2]), whereas no associations were observed with questionnaire-based measures of social cognition. These findings support eye-tracking as an observer-independent tool to detect environmentally related alterations in social perception that may not be captured by conventional questionnaire-based assessments and underscore the need to integrate objective behavioral phenotyping into environmental epidemiology.

Exposure to neurotoxic metals early in life can disrupt brain development and increase risk of later mental health problems, but vulnerable periods and underlying mechanisms remain unclear. We examined how early life exposures to mixtures of metals affect children’s brain and behavior using naturally shed “baby” teeth as a biomarker of direct exposure. We studied 489 children aged 8 to 14 years and reconstructed weekly concentrations of nine metals from 20 weeks before birth to 40 weeks after birth. We assessed behavior using standardized questionnaires and measured brain structure and function with magnetic resonance imaging. Using lagged weighted quantile sum regression, we identified sensitive developmental windows during which higher exposure to metal mixtures was linked to more behavioral problems, smaller brain volume, reduced brain global efficiency, and weaker white matter integrity. Findings suggest that the developing brain is especially vulnerable to metals in early life, with lasting effects into adolescence.

This study investigated the intricate relationship between sociodemographic factors and mental health indicators among a cohort of pregnant adolescents. We conducted a cross-sectional analysis of 338 primigravidas, aged 11–19 years, systematically collecting sociodemographic data, including age, socioeconomic status, schooling, occupation, marital status, and family structure. Mental health was assessed using validated scales for depressive symptoms (EPDS), state–trait anxiety inventory (STAI), self-esteem (Coopersmith), and perceived stress (PSS-4). A substantial portion of the cohort presented with significant mental health challenges: 33.5% screened positive for depressive symptoms, 18% for state anxiety, 23% for trait anxiety, 67% reported low self-esteem, and 52% experienced high perceived stress. Specifically, working adolescents exhibited markedly higher odds of depressive symptoms (OR 3.516), low self-esteem (OR 1.091), elevated state anxiety (OR 2.803), and increased trait anxiety (OR 2.455). Adolescents living with a partner also showed a greater likelihood of reporting depressive symptoms (OR 1.921), heightened state anxiety (OR 1.772), and increased trait anxiety (OR 2.335). Additionally, lower educational attainment (OR 1.885) and residing in extended family structures (OR 1.894) were associated with diminished self-esteem. These findings underscore the significant influence of occupation, family structure, and marital status on the mental health trajectories of pregnant adolescents. Consequently, promoting educational continuity and fostering greater autonomy in personal life decisions for adolescents could be crucial interventions to improve their emotional well-being during pregnancy.

Background/Objectives: Overweight and obesity during pregnancy are metabolic risk factors that may compromise offspring brain development. The first 1000 days of life represent a critical window in which neurodevelopmental trajectories are shaped by intrauterine and early-life exposures. The 6- and 12-month milestones are key checkpoints where deviations may emerge, and interventions are most effective. This study evaluated the association between maternal pregestational weight status and infant neurodevelopment at 6 and 12 months of age. Methods: Mother and infant pairs from the OBESO perinatal cohort in Mexico City were included. Women in the first trimester of pregnancy were classified as normal weight and overweight/obesity according to their pregestational body mass index (pBMI), calculated from self-reported pre-pregnancy weight. Infant neurodevelopment was assessed at 6 and 12 months using the Bayley Scales of Infant Development III, Third Edition (BSID-III). Descriptive, bivariate and multiple linear regression analyses with mixed effects correction were conducted. Results: Among 97 mother–infant pairs, infants of mothers with overweight/obesity had lower language and socio-emotional scores at 12 months. Higher maternal pBMI was correlated with lower motor scores at 6 and 12 months, and with lower language scores at 12 months. Longitudinal analysis showed that maternal overweight/obesity was associated with a significant decline in language development from 6 to 12 months. (p = 0.002). Conclusions: Maternal pregestational overweight or obesity may negatively influence early neurodevelopment, particularly affecting language and cognitive domains during the first year of life. These early deficits could reflect alterations in intrauterine programming associated with maternal metabolic status.

Prenatal exposure to air pollution is a major public health concern due to its potential to impair fetal brain development. This study examined whether maternal inflammatory and oxidative stress biomarkers mediate the association between trimester-specific air pollutant exposure during pregnancy and infant neurodevelopment at one year. We analyzed 87 mother–infant pairs from the OBESO perinatal cohort in Mexico City. Trimester-specific exposure to CO, PM₁₀, PM_2.5, SO₂, and O₃ was estimated using residential geolocation. Biomarkers were measured in the first and third trimesters by protocol, and intra-pregnancy change was calculated as Δ(3T–1T) for cytokines (IL-1β, IL-6, TNFα) and oxidative stress markers (malondialdehyde (MDA), protein carbonyls (PC), and total antioxidant capacity (TAC). Infant neurodevelopment at 12 months was assessed using Bayley-III. Exploratory mediation analyses were conducted, adjusting for gestational age at birth, pre-eclampsia, gestational diabetes, fetal growth restriction, marital status, mode of delivery, and infant sex; bootstrapping was applied to obtain robust estimates. Third-trimester CO exposure was associated with poorer receptive language (coef = 0.754, p = 0.02). PM_2.5 exposure showed direct effects on expressive language in the first (coef = 0.01, p = 0.04) and third trimesters (coef = 0.007, p = 0.015) in models including IL-1β. Third-trimester O₃ and SO₂ exposures were linked to lower expressive scores in models including TNFα (coef = 0.007, p = 0.02), MDA (coef = 0.008, p = 0.04), and PC (coef = 0.007, 95% p = 0.04). Meanwhile PM₁₀ exposure was associated with socio-emotional outcomes in models with IL-6 and TAC (coef = 0.003, p = 0.04). These findings indicate that maternal inflammation and oxidative stress biomarkers did not mediate the associations between prenatal air pollution exposure and infant neurodevelopment, and this study cannot elucidate their specific biological role in neurodevelopment.

Objective: To determine if prenatal socioeconomic status (SES) is associated with childhood working memory (WM), we constructed a more precise, integrative measure of WM using variables from multiple tasks that may provide a more representative measure of WM. Study Design: We used data from a prospective birth cohort study in Mexico City, Mexico, with N = 515 children aged 6–9 years. Prenatal SES was measured using the Mexican Association of Marketing Research and Public Opinion Agencies (AMAI) index. We created a latent variable for nonverbal working memory using multiple tasks (Cambridge Neuropsychological Test Automated Battery spatial working memory, operant chamber Delayed Match to Sample and Incremental Repeated Acquisition). Structural equation models were used to assess associations between prenatal SES and nonverbal working memory, adjusting for child demographics (e.g., age and sex), prenatal exposures (e.g., exposures to lead, arsenic, and secondhand smoke), and family (current SES, maternal IQ) variables. Results: Children had a mean age of 6.6 years [SD 0.6], and 50.5% were boys. Using confirmatory factor analysis, we constructed a latent variable of nonverbal working memory, which was measurement invariant across child sex. Prenatal SES was associated with childhood nonverbal working memory (standardized factor loading = 0.17; p = 0.004). These associations were modified by child sex. Higher prenatal SES was significantly associated with higher childhood WM in females (standardized factor loading = 0.26; p = 0.002), but not in males. Conclusions: Prenatal socioeconomic status is a predictor of childhood working memory, but it may be a stronger predictor for girls compared with for boys.