Leisure Screen Time and the Risk of Six Neurodevelopmental Disorders: A Two-Sample Mendelian Randomization Study.

Researchers studied whether screen time might cause or prevent certain developmental conditions in children. They looked at genetic information from over 700,000 people and found that having genes linked to more screen time was connected to lower ADHD risk but higher intellectual disability risk. Screen time didn't seem to affect autism, learning problems, speech issues, or Tourette syndrome. More research is needed to confirm these findings.

This Mendelian randomization study examined potential causal relationships between leisure screen time and six neurodevelopmental disorders using genetic data from 703,901 European participants across 51 studies. Using five statistical methods, researchers found that genetic predisposition to increased leisure screen time was associated with reduced ADHD risk (OR=0.68) but increased intellectual disability risk (OR=1.66). No causal relationships were identified for autism spectrum disorder, learning disability, speech disorder, or Tourette disorder. The findings suggest screen time may have differential effects on neurodevelopmental outcomes, though the authors acknowledge limitations and call for larger longitudinal studies for validation.

Findings suggest screen time effects on neurodevelopment may be condition-specific rather than universally harmful. Clinicians should consider individual risk factors when providing screen time guidance, particularly for families with ADHD or intellectual disability concerns.

Study uses genetic proxies rather than direct screen time measurement, focuses only on European ancestry populations, and cannot establish optimal screen time amounts or account for content quality differences. Causal interpretations require validation through longitudinal studies.

Neurodevelopmental disorders (NDDs)-including autism spectrum disorder, attention deficit hyperactivity disorder (ADHD), intellectual disability, learning disability, speech disorder, and Tourette disorder-impact brain development and impair social, learning, and occupational functioning. We performed a Mendelian randomization (MR) analysis using summary data from global genome-wide association studies to investigate the potential causal relationship between leisure screen time (LST) and NDDs risk. Our dataset comprised 703,901 participants of European ancestry from 51 studies, with 256,725 individuals in the LST-valid sample. We investigated causal associations with six types of NDDs using five MR methods: inverse-variance weighted (IVW), MR Egger, weighted median, simple mode, and weighted mode.

IVW was the primary method due to its efficiency and precision. Heterogeneity and horizontal pleiotropy were assessed using IVW and MR Egger, while the other methods served as sensitivity analyses to confirm robustness. The IVW method revealed that each standard deviation increase in LST was associated with a reduced risk of ADHD (OR = 0.68; 95% CI: 0.52-0.89) and an elevated risk of intellectual disability (OR = 1.66; 95% CI: 1.26-2.18). These associations were consistent with the weighted median analysis (ADHD: OR = 0.68; 95% CI: 0.47-0.98; intellectual disability: OR = 1.51; 95% CI: 1.06-2.14).

Our findings suggest that genetic predisposition to increased LST is causally associated with a lower risk of ADHD but a higher risk of intellectual disability, with no evidence for a causal relatawdionship with the other four NDDs. Larger or longitudinal studies are needed for further validation.