Smartphone use health outcomes in children and adolescents: A systematic review of behavioral, developmental, and environmental risk pathways

Table 6 Neurodevelopmental outcomes associated with smartphone/screen exposure by age group and developmental domain

Age group	Ref.	Sample (n)	Developmental domain	Assessment tool	Exposure measure	Main findings	Direction	Appraisal tool	Primary bias considerations	Overall risk
Infants (approximately 18 months)	Gastaud et al[51], 2023 (Brazil)	470	Global cognitive development	BSID-III	≥ 2 hours/day screen time	≥ 2 hours/day associated with significantly lower cognitive scores (β = -3.6 to -0.5); 58.8% ≥ 1 hour/day	Negative (dose-related)	JBI (analytical)	Strengths: Population-based sample (n = 470); utilized standardized BSID-III for objective cognitive assessment. Limitations: Screen time based on caregiver-reported questionnaires (recall bias)	Low
Preschool (3-5 years)	Chaibal and Chaiyakul[52], 2022 (Thailand)	85	Gross motor	Denver Developmental Screening Test II	Mean 82.8 ± 62.8 minutes/day smartphone/tablet use	Significant correlation between usage duration and gross motor delay	Negative	JBI (analytical)	Strengths: Used the Denver II screening tool for multi-domain developmental assessment. Limitations: Small sample size (n = 85); 7-day retrospective recording of usage may involve estimation errors	Moderate
			Fine motor-adaptive	Denver II	Same	32.9% suspected delay; higher use correlated with poorer outcomes	Negative
			Language	Denver II	Same	9.4% suspected delay; weaker association	Negative (small)
			Personal-social	Denver II	Same	11.8% suspected delay; limited statistical strength	Inconclusive
Children with NDs	Butti et al[53], 2026 (Italy)	407 children (352 families)	Functional regulation, attention, behavioral control	Survey-based parental report	Device type & daily screen exposure	Older children more likely high-use; ADHD associated with difficulty disengaging; parental screen use predicted child exposure	Vulnerability-enhancing	JBI (analytical)	Strengths: Focused on a high-risk clinical population (children with NDs); relatively large sample (n = 407). Limitations: Self-selection bias from online survey distribution; parent-reported data for both child and own usage	Moderate
Educational/therapeutic context (professional training)	Mostowfi et al[54], 2022	30 OT students	Knowledge of NDT	Knowledge questionnaire; QUIS usability scale	Structured educational app use (2 weeks)	Significant improvement in knowledge acquisition; high usability	Positive (structured use)	JBI (quasi-experiment)	Strengths: Includes a control group; pre- and post-intervention knowledge testing. Limitations: Very small sample (n = 30); unblinded intervention in an educational setting	Moderate to high

To evaluate the neurodevelopmental outcomes associated with smartphone and screen exposure, the following Risk of Bias assessment has been performed utilizing the Joanna Briggs Institute checklists for cross-sectional and quasi-experimental studies, as outlined in your methods section. NDs: Neurodevelopmental disorders; OT: Occupational therapy; NDT: Neurodevelopmental treatment; BSID-III: Bayley Scales of Infant Development-III; QUIS: Questionnaire for User Interaction Satisfaction; ADHD: Attention-deficit hyperactivity disorder; JBI: Joanna Briggs Institute.