The associations of secondhand smoke exposure with neurodevelopmental disorders and critical time window identification: A systematic review and meta-analysis.

BACKGROUND: Secondhand smoke (SHS) exposure was harmful for brain development. However, the association between SHS exposure and NDDs diagnosis were unclear. OBJECTIVES: To evaluate associations between SHS exposure and NDDs diagnosis, identify critical time windows, and summarize the strength of evidence. METHODS: To investigate the associations of SHS exposure and the development of NDDs, we searched Ovid, EMBASE, Web of Science, Cochrane Library, and PubMed for all the relevant studies up to 31 March 2023. The risk estimates and standardized mean differences (SMD) for the individuals with any NDDs who were exposed to SHS exposure compared with those unexposed or low-exposed. RESULTS: The results showed that a total of 31,098 citations were identified, of which 54 studies were included. We identified significant associations between SHS exposure and the risks of NDDs including specific types of NDDs like attention deficit hyperactivity disorder (ADHD) and learning disabilities (LD) despite the observed heterogeneity for NDDs and ADHD. We also observed a significant association between cotinine exposure and ADHD. However, inconsistent ratings between the two quality-of-evidence methods for all the meta-analyses indicated the current evidence of the associations and the potential exposure window remained inconclusive. DISCUSSION: Our findings suggested that SHS exposure was associated with a higher risk of developing ADHD and LD, with inconclusive quality-of-evidence. In addition, period-specific associations remained unclear based on current evidence.

Pre-conceptional and prenatal exposure to secondhand smoke and autism spectrum disorder: a national multi-center study in China.

BACKGROUND: Despite extensive research evaluating the association between prenatal exposure to secondhand smoke (SHS) and the development of autism spectrum disorders (ASD), no study has investigated the association by considering the pre-conceptional period. This study aimed to investigate the associations of pre-conceptional and prenatal SHS exposure and the development of ASD among toddlers. METHODS: In this cross-sectional study, parents of 6049 toddlers aged 16-30 months were recruited from 7 tertiary hospitals, 21 communities, and 7 kindergartens located in seven cities in six provinces from five geographical regions of China. We analyzed the associations of SHS exposure and the odds of ASD among toddlers in different exposure windows (pre-conceptional and/or prenatal periods). Data were analyzed from November 2021 to January 2022. RESULTS: Among the 6049 toddlers included in the analysis [22.7 (4.1) months; 44.8% girls], 71 were identified and diagnosed with ASD. Compared with the unexposed toddlers, toddlers with pre-conceptional SHS exposure had higher odds of ASD (OR 2.30, 95% CI 1.36-3.84), while we observed a non-significantly positive association regarding prenatal SHS exposure. When considering both pre-conceptional and prenatal periods, toddlers who were continuously exposed to SHS during these two periods had higher odds than those without SHS exposure (OR 2.32, 95% CI 1.24-4.14). CONCLUSION: We reported positive SHS-ASD associations when exposed during the pre-conceptional period and continuously exposed during pre-conceptional and prenatal periods, emphasizing the critical window of pre-conception for targeted intervention on smoking.

Adherence to 24-hour movement guidelines in children with mental, behavioral, and developmental disorders: Data from the 2016-2020 National Survey of Children's Health.

BACKGROUND: Adopting a healthy lifestyle during childhood could improve physical and mental health outcomes in adulthood and reduce relevant disease burdens. However, the lifestyles of children with mental, behavioral, and developmental disorders (MBDDs) remains under-described within the literature of public health field. This study aimed to examine adherence to 24-hour movement guidelines among children with MBDDs compared to population norms and whether these differences are affected by demographic characteristics. METHODS: Data were from the 2016-2020 National Survey of Children's Health-A national, population-based, cross-sectional study. We used the data of 119,406 children aged 6-17 years, which included 38,571 participants with at least 1 MBDD and 80,835 without. Adherence to the 24-hour movement guidelines was measured using parent-reported physical activity, screen time, and sleep duration. RESULTS: Among children with MBDDs, 20.3%, 37.0%, 60.7%, and 77.3% met the physical activity, screen time, sleep, and at least 1 of the 24-hour movement guidelines. These rates were lower than those in children without MBDDs (22.8%, 46.2%, 66.7%, and 83.4%, respectively; all p < 0.001). Children with MBDDs were less likely to meet these guidelines (odds ratio (OR) = 1.21, 95% confidence interval (95%CI): 1.13-1.30; OR = 1.37, 95%CI: 1.29-1.45; OR = 1.29, 95%CI: 1.21-1.37; OR = 1.45, 95%CI: 1.35-1.56) than children without MBDDs. Children with emotional disorders had the highest odds of not meeting these guidelines (OR = 1.43, 95%CI: 1.29-1.57; OR = 1.48, 95%CI: 1.37-1.60; OR = 1.49, 95%CI: 1.39-1.61; OR = 1.72, 95%CI: 1.57-1.88) in comparison to children with other MBDDs. Among children aged 12-17 years, the difference in proportion of meeting physical activity and screen time guidelines for children with vs. children without MBDD was larger than that among children aged 6-11 years. Furthermore, the above difference of meeting physical activity guidelines in ethnic minority children was smaller than that in white children. CONCLUSION: Children with MBDDs were less likely to meet individual or combined 24-hour movement guidelines than children without MBDDs. In educational and clinical settings, the primary focus should be on increasing physical activity and limiting screen time in children aged 12-17 years who have MBDDs; and specifically for white children who have MBDDs, increasing physical activity may help.