Socioeconomic status and economic hardship attenuated the associations between early tobacco or nicotine use and brain outcomes in preadolescent children.

Objectives: Early tobacco use (before age 11) is linked to poorer cognition and reduced cortical surface area and volume in young adolescents. This study examined how socioeconomic status (SES) factors - parental education, household income, and economic hardships - influenced these associations.

Methods: Using baseline (N=11,876) and year 3 (N=10,414) datasets from the Adolescent Brain Cognitive Development study, we assessed the impact of baseline tobacco/nicotine use initiation on cognitive scores, cortical volume, thickness, and surface area across the entire cohort and in propensity-matched subgroups. Linear mixed effects models controlled for SES and other covariates, with multiple comparison correction. Analyses were cross-sectional at baseline and longitudinal with both timepoints.

Results: Compared to non-users (N=11,240), early users (N=110) had more advanced pubertal development (p=0.003) and economic hardships (p<0.001), but fewer girls (p=0.04), Hispanics (p=0.02), parents with graduate degrees (p<0.001) and high-income families >$100 K (p=p<0.001). Relative to non-users, early users had poorer cognitive scores (Cohen's d: -0.69 to -0.24), smaller surface areas (Cohen's d: -2.28 to -0.22), similar cortical thickness at both timepoints, and by year 3, smaller cortical volumes (Cohen's d: -1.06 to -1.24). However, SES-adjustments eliminated cognitive scores and volumes differences and reduced cortical surface area effects at both timepoints (Cohen's d: -1.92 to -0.51). After propensity score matching, early users and non-users showed no cognitive or brain differences, regardless of SES adjustments.

Conclusions: Adjusting for SES eliminated the negative impact of early tobacco/nicotine use on cognition and reduced its effect on brain surface area, underscoring the importance of SES in morphometry studies.