Abstract
Background: Watching television in childhood and adolescence has been linked to a number of adverse health indicators including obesity, poor fitness, smoking and raised cholesterol. However, there have been no longitudinal studies of childhood viewing and adult health. We explored these associations in a birth cohort followed to age 26.
Methods: Approximately 1000 unselected individuals born in Dunedin, New Zealand in 1972-1973 have been assessed at regular intervals up to age 26. The associations between earlier television viewing and Body Mass Index (BMI), cardio-respiratory fitness (maximum aerobic power assessed by a submaximal cycling test), serum cholesterol, smoking status and blood pressure at age 26 were examined using regression analyses.
Findings: Average weeknight viewing hours between age 5 and 15 were associated with increased BMI, lower cardio-respiratory fitness, increased cigarette smoking and raised serum cholesterol (P values <0ยท05). There was no significant association with blood pressure. Except for cholesterol, these associations persisted after adjustment for potential confounding factors including childhood socio-economic status, age 5 BMI, parental BMI, parental smoking, and age 15 physical activity and dietary indicators. Population attributable fractions indicate that 17% of overweight, 15% of raised serum cholesterol, 16% of smoking and 15% of poor fitness at age 26 could be attributed to watching television for more than 2 hours a day during childhood and adolescence. Interpretation: Television viewing in childhood and adolescence is associated with overweight, poor fitness, smoking and raised cholesterol in adulthood. Excessive viewing may have long-lasting adverse effects on health.