Household secondhand smoke exposure and learning difficulties in children and adolescents: A cross-sectional study on the mediating roles of attention, memory, and adaptability

INTRODUCTIONSecondhand smoke exposure is a prevalent and modifiable factor linked to adverse neurodevelopmental outcomes in children and adolescents.However, the mechanisms through which household smoking contributes to learning difficulties remain unclear.Therefore, this study aimed to investigate the association between secondhand smoke exposure and learning difficulties in a nationally representative sample of children and adolescents, and to examine the potential mediating roles of attention difficulties, memory difficulties, and difficulties accepting change.METHODS This pooled secondary data analysis used National Health and Nutrition Examination Survey (NHANES, USA) 2021-2023 data from 2455 participants aged 5-17 years.The exposure was household smoking status; the outcome was parent/self-reported learning difficulties; and potential mediators were attention, memory, and adaptability difficulties.Using weighted multivariable logistic regression, we adjusted for demographics, poverty income ratio, anxiety, and depression.Mediation effects were quantified via the Sobel test. RESULTSThe prevalence of learning difficulties was significantly higher in children from households with smokers (24.6%) compared to those without (17.4%,OR=1.54; 95% CI: 1.24-1.92,p=0.002).After full adjustment for covariates, secondhand smoke exposure remained significantly associated with increased odds of learning difficulties (adjusted odds ratio, AOR=1.43;95% CI: 1.14-1.79,p=0.002).Mediation analysis confirmed significant indirect effects through memory difficulties (52.1% mediated; β=0.192; 95% CI: 0.055-0.335,p=0.006), attention difficulties (44.3%; β=0.164; 95% CI: 0.070-0.265,p<0.001), and difficulties accepting change (36.4%; β=0.135; 95% CI: 0.074-0.199,p<0.001).CONCLUSIONS Household secondhand smoke exposure is independently associated with learning difficulties in US children and adolescents.This association is predominantly mediated through impairments in core cognitive functions, particularly attention, memory, and adaptability.