Associations of changes in physical activity and screen time and social-emotional development among toddlers

BACKGROUND: Early childhood is a critical window of rapid neurocognitive and social-emotional development. Toddlerhood (age 1-2 years), in particular, is characterized by rapid changes in both screen media exposure and movement behaviors. This study examined associations between changes in daily screen time and moderate- to vigorous-intensity physical activity (MVPA) from ages 1.5 to 2.5 years and social-emotional functioning at age 2.5 years. METHODS: This study analyzed data from the Child and Mother Physical Activity Study (CAMPAS). Daily screen time was proxy-reported by mothers, and MVPA was measured using hip-worn ActiGraph accelerometers. Social-emotional functioning at age 2.5 years was assessed using the Strengths and Difficulties Questionnaire (SDQ). Multivariable linear regression models predicted SDQ scores at age 2.5 years, including annualized changes in screen time and MVPA as primary predictors, adjusting for age, sex, neighborhood resources, and baseline SDQ scores. RESULTS: Analysis included 116 children (53% female) who completed the SDQ at age 2.5 years. From age 1.5 to 2.5 years, mean daily screen time increased from 43 (SD = 46) to 69 min (SD = 60), and mean daily MVPA increased from 72 (SD = 22) to 90 min (SD = 22). Longitudinal changes in screen time were not correlated with changes in MVPA (r=-0.08; p = 0.42). A multivariable regression model estimated that a 30-minute annualized increase in daily screen time was associated with a 0.5-point higher SDQ total difficulty score (p = 0.04) and a 30-minute annualized increase in daily MVPA was associated with a 1.0-point lower SDQ total difficulty score (p = 0.04). CONCLUSIONS: During toddlerhood, increases in physical activity and screen time were independently associated with social-emotional functioning in opposite directions. These findings highlight toddlerhood as a sensitive window for promoting physical activity and minimizing screen exposure to support healthy social-emotional development.