Smartphone ownership at age 12 was associated with a greater likelihood of several eating disorder symptoms 2 years later, with self-worth tied to weight showing the strongest association at approximately twice the risk.
Researchers analyzed data from 8,957 adolescents in the Adolescent Brain Cognitive Development Study, a longitudinal cohort recruited from 21 US sites. Data collected from 2018 to 2024 were used for cross-sectional analyses at age 12 years and longitudinal analyses at age 14 years. Overall, 6,225 participants (70%) owned a smartphone at age 12 years. The analyses were weighted to approximate US sociodemographic characteristics and adjusted for demographic and socioeconomic characteristics, depressive and attention-deficit/hyperactivity symptoms, pubertal status, body weight, parental monitoring, ownership of other devices, and study site.
Eating disorder (ED) symptoms were assessed using the Kiddie Schedule for Affective Disorders and Schizophrenia. Adolescents reported whether they experienced binge-eating, inappropriate compensatory behaviors to prevent weight gain, worry about weight gain, or self-worth tied to weight. Researchers examined each symptom and the presence of any ED symptom at ages 12 and 14 years. Longitudinal analyses additionally accounted for ED symptoms at age 12 years.
In adjusted longitudinal analyses, adolescents who owned a smartphone at age 12 years had a 49% higher risk of reporting any ED symptom at age 14 years compared with those who did not. Smartphone ownership was also associated with a 67% higher risk of binge-eating symptoms, a 50% higher risk of inappropriate compensatory behaviors, and approximately twice the risk of self-worth tied to weight. No association was found with worry about weight gain.
Cross-sectional analyses showed a similar pattern at age 12 years. Smartphone ownership was associated with a 61% higher prevalence of binge-eating symptoms, more than twice the prevalence of self-worth tied to weight, and a 36% higher prevalence of any ED symptom. Smartphone ownership was not associated with compensatory behaviors or worry about weight gain in the adjusted cross-sectional analyses.
Among adolescents who owned smartphones, 16% reported at least 1 ED symptom at age 12 years compared with 24% at age 14 years. At age 14 years, inappropriate compensatory behaviors were the most prevalent symptom among smartphone owners, reported by 21%.
Smartphone ownership was associated with greater worry about weight gain among female adolescents but not male adolescents. Worry about weight gain was uncommon in the overall sample, which may have limited the researchers' ability to detect differences by smartphone ownership.
The study had several limitations. Smartphone ownership was not randomized, reverse causation could not be excluded, and residual confounding may have remained despite adjustment for numerous potential confounders, preventing causal conclusions. Potential influences, including school or online bullying, neurodevelopmental conditions, and pre-existing or emerging mental health problems, were not accounted for. Smartphone ownership also did not capture the content adolescents consumed orhow they used their smartphones. ED symptoms were self-reported and coded dichotomously, limiting assessment of symptom severity. Participants excluded because of missing data differed from the analytic sample in some demographic and socioeconomic characteristics, which may have introduced sampling bias and limited generalizability.
The researchers emphasized that further research is needed to determine the mechanisms underlying the observed associations. “Future studies are needed to better characterize the mechanisms underlying the association between early smartphone ownership and subsequent ED symptoms in adolescents,” wrote first author Jason M. Nagata, MD, of the University of California, San Francisco, and colleagues.
The authors reported no conflicts of interest. The study and the ABCD Study received NIH and other federal funding.
Source: JAMA Network Open