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

Table 5 Executive function outcomes associated with smartphone use by age group and study design

Age group	Ref.	Study design	Country	Sample size (n)	EF domains assessed	Main findings	Direction of association	Appraisal tool	Primary bias considerations	Overall risk
Preschool (2-6 years)	Lakicevic et al[43], 2025	Cross-sectional	Russia	1016	Cognitive flexibility, verbal working memory, and inhibition	Screen time weakly negatively correlated with flexibility and verbal WM; very weak negative correlation with inhibition	Negative (small effect)	JBI	Strengths: Large, representative sample (n = 1016). Limitations: Reliance on parent-reported screen time; cross-sectional design limits causal interpretation of EF deficits	Low
	Horowitz-Kraus et al[44], 2024	EEG cross-sectional	Israel	4-year-old (n ≈ 80)	Behavioral EF, N200, P300	Longer screen exposure is associated with poorer EF performance and altered executive-related EEG markers	Negative	JBI	Strengths: Use of objective neurophysiological markers (N200, P300) alongside behavioral tasks. Limitations: Small sample size (n ≈ 80); specific to 4-year-old	Moderate
	Oflu et al[45], 2021	Cross-sectional	Turkey	240	Emotional regulation (behavioral EF)	≥ 4 hours/day associated with higher emotional lability and negativity	Negative (dose-related)	JBI	Strengths: Identifies a clear dose-response relationship (at ≥ 4 hours). Limitations: Potential for social desirability bias in parent reports	Moderate
School-age (7-12 years)	Al-Amri et al[46], 2023	Cross-sectional	Saudi Arabia	186	Selective attention accuracy, reaction time	Smartphone addiction associated with reduced attention accuracy; no difference in reaction time	Negative	JBI	Strengths: Assessed specific attentional accuracy rather than general cognition. Limitations: Small sample size (n = 186)	Moderate
	Shekhawat et al[47], 2024	Cross-sectional	India	50	Parent-reported cognitive flexibility	> 4 hours/day associated with cognitive impairment in 66.7%	Negative	JBI	Strengths: Focuses on both cognitive and physical (posture) outcomes. Limitations: Very small sample (n = 50) and use of a self-constructed, unvalidated e-questionnaire	High
Adolescents (13-18 years)	Tauste-Garcia et al[48], 2025	Cross-sectional	Spain	269	Parent-rated EF, performance-based EF	PSU associated with greater parent-reported EF deficits; no difference in lab tasks	Negative (behavioral > performance)	JBI	Strengths: High-quality comparison between subjective (parent-rated) and objective (lab-based) EF tasks	Low to moderate
	Yum et al[49], 2025	RCT protocol	Hong Kong	Planned n = 240	Attention, inhibitory control, and EEG	Trial targeting smartphone overuse in ADHD adolescents; outcomes pending	Not yet available	RoB 2	Strengths: Planned randomization and use of objective EEG markers in a high-risk (ADHD) population. Note: As a protocol, risk assessment is based on design intent	Low (for design)
Young adults (comparative experimental evidence)	Ward et al[50], 2017	Laboratory experimental	United States	> 800	Working memory (OSpan), fluid intelligence (Raven), sustained attention	Smartphone presence (desk vs other room) reduced working memory and fluid intelligence; sustained attention was unaffected	Negative (causal evidence)	RoB 2	Strengths: Large sample size (n > 800); randomized experimental conditions allow for causal claims regarding “brain drain”	Low

The table illustrates that across developmental stages, smartphone exposure is consistently associated with executive function difficulties. In preschool children, studies show small yet consistent negative associations between screen time and core executive function domains, accompanied by emerging neurophysiological correlations. Among school-age children, excessive smartphone use is associated with reduced attentional accuracy and increased parent-reported cognitive impairment. In adolescents, behavioral executive dysfunction is observed more frequently than deficits on laboratory-based tasks, suggesting a greater impact on everyday self-regulation than on isolated cognitive performance. Experimental evidence further reinforces these findings, demonstrating strong causal effects whereby the mere presence of a smartphone can deplete attentional resources and diminish working memory capacity. Assessments of bias of included studies utilized the Joanna Briggs Institute checklist for cross-sectional studies and the Cochrane Risk of Bias framework for experimental designs and randomized controlled trial protocols. EF: Executive function; WM: Working memory; JBI: Joanna Briggs Institute; EEG: Electroencephalography; PSU: Problematic smartphone use; RCT: Randomized controlled trial; ADHD: Attention-deficit hyperactivity disorder; RoB 2: Cochrane Risk of Bias.