Screen time under 2 years of age and autism risk at 12 years | Image Credit: © Андрей Журавлев - © Андрей Журавлев - stock.adobe.com.

Investigators of a study evaluated the association between screen time among children and autism spectrum disorder (ASD) by using socioeconomic factors as instrumental variables, according to a November 2024 research letter published in JAMA Pediatrics.¹

Background

According to research letter authors Ping-I. Lin, MD, PhD; Weng Tong Wu; and Yue-Liang Leon Guo, MD, PhD, there is an increase of data that has suggested screen time in early childhood (up to 5 years of age) can be linked to risk of ASD. The casual relationship "remains elusive," the study authors wrote.¹

They noted a previously-published study from 2022 that reported a positive association between ASD risk and length of screen time in a sample of over 84,000 children. In another study, results suggested that daily screen time of 8.5 hours or more was associated with an ASD diagnosis.^1,2

"However, such an association was not confirmed in other populations, possibly because of unmeasured confounders," stated the authors.¹

Study details

The investigators used data from the Longitudinal Study of Australian Children, with outcome variables assessed between 2016 and 2018.¹

They defined early childhood screen time as the weekly number of hours of exposure to videos, television, or other internet-based programs at 2 years of age. Using multivariable logistic regression models, authors determined whether early childhood screen time was linked with ASD risk at 12 years of age by adjusting for sex, family income, and maternal education level.¹

"The instrumental variable method was then used to interrogate the association between early childhood screen time and risk of ASD by assuming that some socioeconomic factors can only directly be associated with screen time instead of ASD risk," stated the authors.¹

Statistical significance was set at 2-sided P = .05 using the Wald test.¹

Results

In all, the study sample was made up of 5107 children from the birth cohort in Australia, with a weighted sample size of 243,046 children. At 12 years of age, 145 children had a parent-reported diagnosis of ASD. Based on bivariate analysis, results demonstrated that screen time was significantly positively associated with¹:

• Diagnosis of ASD (adjusted odds ratio [AOR], 1.83; 95% CI, 1.26-2.59; P = .001)
• Male sex (AOR, 1.31; 95% CI, 1.14-1.50; P < .001)
• Lower maternal education attainment (AOR, 1.54; 95% CI, 1.39-1.85; P < .001)
• Lower family income (AOR, 1.49; 95% CI, 1.30-1.71; P < .001).

Results demonstrated that race and ethnicity and other perinatal covariates were not associated with screen time.¹

AORs from regression models demonstrated that ASD risk was "significantly greater in children with more than 14 hours of weekly screen time compared with children with less than 14 hours of weekly screen time," by 2 years of age, the authors wrote (AOR, 1.79; 95% CI, 1.24-2.58), adjusting sex, maternal education, and family income.¹

A study limitation was the possibility of residual confounding effects because the validity of the instrumental variable model depended on the strength of the instruments (maternal education and family income), which may not fully account for unmeasured socioeconomic or environmental factors.¹

Conclusion

"Clinicians could inquire about screen time during early childhood as part of a broader assessment of child development," said the investigators. "Interventions should address underlying socioeconomic factors, providing resources to reduce adverse health impacts of screen time."¹

References:

1. Lin P, Wu WT, Guo YL. Screen Time Before 2 Years of Age and Risk of Autism at 12 Years of Age. JAMA Pediatr. 2025;179(1):90–91. doi:10.1001/jamapediatrics.2024.4432

2. Kushima M, Kojima R, Shinohara R, et al. Association Between Screen Time Exposure in Children at 1 Year of Age and Autism Spectrum Disorder at 3 Years of Age: The Japan Environment and Children’s Study. JAMA Pediatr. 2022;176(4):384–391. doi:10.1001/jamapediatrics.2021.5778