Socioeconomic disparities and sexual dimorphism in neurotoxic effects of ambient fine particles on youth IQ: A longitudinal analysis

<div><p>Mounting evidence indicates that early-life exposure to particulate air pollutants pose threats to children’s cognitive development, but studies about the neurotoxic effects associated with exposures during adolescence remain unclear. We examined whether exposure to ambient fine particles (PM_2.5) at residential locations affects intelligence quotient (IQ) during pre-/early- adolescence (ages 9–11) and emerging adulthood (ages 18–20) in a demographically-diverse population (N = 1,360) residing in Southern California. Increased ambient PM_2.5 levels were associated with decreased IQ scores. This association was more evident for Performance IQ (PIQ), but less for Verbal IQ, assessed by the Wechsler Abbreviated Scale of Intelligence. For each inter-quartile (7.73 μg/m³) increase in one-year PM_2.5 preceding each assessment, the average PIQ score decreased by 3.08 points (95% confidence interval = [-6.04, -0.12]) accounting for within-family/within-individual correlations, demographic characteristics, family socioeconomic status (SES), parents’ cognitive abilities, neighborhood characteristics, and other spatial confounders. The adverse effect was 150% greater in low SES families and 89% stronger in males, compared to their counterparts. Better understanding of the social disparities and sexual dimorphism in the adverse PM_2.5–IQ effects may help elucidate the underlying mechanisms and shed light on prevention strategies.</p></div

Population characteristics in relation to the overall^a PM_2.5 exposure 1-year prior to IQ assessment.

<p>Population characteristics in relation to the overall<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188731#t001fn001" target="_blank">^a</a> PM_2.5 exposure 1-year prior to IQ assessment.</p

Population characteristics at baseline in relation to full-scale IQ.

<p>Population characteristics at baseline in relation to full-scale IQ.</p

Associations between PM_2.5 and IQ measures.

<p>Associations between PM_2.5 and IQ measures.</p

Summary of anterior chamber angle parameters at baseline and 1 month after cataract extraction by anterior segment optical coherence tomography.

<p>Summary of anterior chamber angle parameters at baseline and 1 month after cataract extraction by anterior segment optical coherence tomography.</p

Ocular characteristics of 98 study eyes.

<p>Ocular characteristics of 98 study eyes.</p

Pearson Correlation Coefficient, R (<i>P</i> value), among Iris-Related Parameters.

<p>Pearson Correlation Coefficient, R (<i>P</i> value), among Iris-Related Parameters.</p

Estimated Regression Coefficient (β) (±standard error) as well as associated <i>P</i> value.

<p>Estimated Regression Coefficient (β) (±standard error) as well as associated <i>P</i> value.</p

Pearson correlation coefficients (r) between total CPS scores at wave 3 (when brain scans were collected) and brain volumes.

<p>^a The P values shown are two-tailed probability tests.</p><p>Pearson correlation coefficients (r) between total CPS scores at wave 3 (when brain scans were collected) and brain volumes.</p

Iris-related parameters as measured by ASOCT.

<p>A = iris cross-sectional area; RICe = radius of iris centroid; SSL = scleral spur landmark; PR = pupillary radius; AISL = anterior iris surface length; SSL-to-PM = scleral spur landmark to pupillary margin.</p