Structural and Functional Neural Correlates in Individuals with Excessive Smartphone Use: A Systematic Review and Meta-Analysis

Abstract

Background: Despite known association of internet addiction with a reduced brain volume and abnormal connectivity, the impact of excessive smartphone use remains unclear. Methods: PubMed, Embase, ClinicalTrial.gov, and Web of Science databases were systematically searched from inception to July 2022 using appropriate keywords for observational studies comparing differences in brain volumes and activations between excessive smartphone users and individuals with regular use by magnetic resonance imaging. Results: Of the 11 eligible studies retrieved from 6993 articles initially screened, seven and six evaluated brain volumes and activations, respectively. The former enrolled 421 participants (165 excessive smartphone users vs. 256 controls), while the latter recruited 276 subjects with 139 excessive smartphone users. The results demonstrated a smaller brain volume in excessive smartphone users compared to the controls (g = −0.55, p < 0.001), especially in subcortical regions (p < 0.001). Besides, the impact was more pronounced in adolescents than in adults (p < 0.001). Regression analysis revealed a significant positive association between impulsivity and volume reduction. Regarding altered activations, the convergences of foci in the declive of the posterior lobe of cerebellum, the lingual gyrus, and the middle frontal gyrus were noted. Conclusions: Our findings demonstrated a potential association of excessive smartphone use with a reduced brain volume and altered activations.

AI evidence extraction

Main findings

Across eligible observational MRI studies, excessive smartphone users had smaller brain volumes than controls (g = −0.55, p < 0.001), particularly in subcortical regions, with a more pronounced effect in adolescents than adults. Regression analysis showed a positive association between impulsivity and volume reduction. Altered activation foci convergences were noted in the declive of the posterior cerebellum, lingual gyrus, and middle frontal gyrus.

Outcomes measured

• Brain volume (MRI)
• Brain activation patterns (MRI/fMRI foci convergence)
• Association between impulsivity and brain volume reduction

Limitations

• Included studies were observational (as stated in methods), limiting causal inference
• Specific exposure metrics (e.g., RF-EMF dose, call time, SAR) not described in the abstract

{
    "study_type": "meta_analysis",
    "exposure": {
        "band": null,
        "source": "smartphone",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Individuals with excessive smartphone use vs regular smartphone use (adolescents and adults)",
    "sample_size": null,
    "outcomes": [
        "Brain volume (MRI)",
        "Brain activation patterns (MRI/fMRI foci convergence)",
        "Association between impulsivity and brain volume reduction"
    ],
    "main_findings": "Across eligible observational MRI studies, excessive smartphone users had smaller brain volumes than controls (g = −0.55, p < 0.001), particularly in subcortical regions, with a more pronounced effect in adolescents than adults. Regression analysis showed a positive association between impulsivity and volume reduction. Altered activation foci convergences were noted in the declive of the posterior cerebellum, lingual gyrus, and middle frontal gyrus.",
    "effect_direction": "harm",
    "limitations": [
        "Included studies were observational (as stated in methods), limiting causal inference",
        "Specific exposure metrics (e.g., RF-EMF dose, call time, SAR) not described in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "excessive smartphone use",
        "MRI",
        "brain volume",
        "brain activation",
        "adolescents",
        "impulsivity",
        "systematic review",
        "meta-analysis"
    ],
    "suggested_hubs": []
}

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