Table 1.
Sample characteristics of Adolescent Brain Cognitive Development (ABCD) Study participants included in the current analysis (N = 4,718)
| Sociodemographic characteristics | Mean (SD) |
|---|---|
| Age at the time of screen time and Fitbit data collection (years) | 12.0 (0.7) |
| Sex, n (%) | |
| Female | 2,244 (47.6%) |
| Male | 2,474 (52.4%) |
| Race/ethnicity, n (%) | |
| White | 2,609 (55.3%) |
| Latino / Hispanic | 726 (15.4%) |
| Black | 854 (18.1%) |
| Asian | 267 (5.7%) |
| Native American | 206 (4.4%) |
| Other | 56 (1.2%) |
| Household income, n (%) | |
| Less than $75,000 | 1,600 (36.5%) |
| 75,000 or more | 2,782 (63.5%) |
| Parent education, n (%) | |
| High school education or less | 605 (12.9%) |
| Some college education or more | 4,104 (87.2%) |
| Parent marital status, n (%) | |
| Parent married/partnered | 3,547 (75.7%) |
| Parent not married/unpartnered | 1,137 (24.3%) |
| Physical activity variables (step count) | |
| Total steps per day | 9722.2 (3346.7) |
| Step categories, n (%) | |
| 1,000 to 6,000 steps per day | 654 (18.4%) |
| > 6,000 to 12,000 steps per day | 2,440 (68.5%) |
| > 12,000 steps per day | 468 (13.1%) |
| Screen time (hours) | |
| Total recreational screen time | 6.6 (5.6) |
| Screen time categories, n (%) | |
| 0 to 4 h per day | 1,962 (41.7%) |
| > 4 to 8 h per day | 1,446 (30.8%) |
| > 8 h per day | 1,293 (27.5%) |
| Cardiovascular disease risk measures | |
| Systolic blood pressure percentile (n = 4,042) | 41.7 (29.2) |
| Diastolic blood pressure percentile (n = 4,042) | 43.4 (24.2) |
| Hemoglobin A1c (percent, n = 1,588) | 5.2 (0.3) |
| Total cholesterol (mg/dL, n = 1,540) | 156.9 (28.8) |
| HDL cholesterol (mg/dL, n = 1,538) | 56.0 (12.8) |
| Data collection period, n (%) | |
| Before the COVID-19 pandemica | 2,886 (81.9%) |
| Before and during the COVID-19 pandemicb | 183 (5.2%) |
| During the COVID-19 pandemicc | 453 (12.9%) |
SD = standard deviation. Cells may not add up to 4,718 due to missing data
a All physical activity data collected before March 13, 2020
b Physical activity data collection started before March 13, 2020 but ended on or after March 13, 2020
c All physical activity data collected on or after March 13, 2020