From Medscape Medical News…
TV Exposure in Early Childhood Predicts Developmental Risks Years Later
May 13, 2010 — A new study of more than 1300 Canadian children has documented wide-ranging and long-term negative psychosocial, behavioral, and cognitive consequences from increased television exposure in early childhood.
In the study, children exposed to more television at 29 months had increased risk for problems in school and poorer health behaviors many years later — as late as the fourth grade, according to research published in the May issue of the Archives of Pediatrics & Adolescent Medicine.
“The study reminds us that television can be a toxic factor in the environment — it’s not merely an innocuous piece of furniture,” lead researcher Linda Pagani, PhD, of the Universite de Montreal, Quebec, Canada, told Medscape Psychiatry. “It’s a public health issue. The results are compelling because we found significant effects [from childhood television exposure] even after a long time lag,” she said.
Dr. Pagani and colleagues examined the influence of television exposure at 29 months and changes in exposure by 53 months on psychosocial, academic, and lifestyle characteristics in the fourth grade.
At 29- and 53-month follow-ups for 1314 children from the Quebec Longitudinal Study of Child Development, parents were asked about the number of hours their children spent watching television each day.
When these children reached the fourth grade, teachers rated their academic performance, including mathematics and reading achievement, and psychosocial adjustment, including the child’s level of aggression and victimization by other children. Teachers also rated children on “classroom engagement” — a score that measured task orientation, compliance, and persistence.
Parents were also asked to report hours of video game use during a typical week, physical activity, and dietary consumption of soft drinks, sweet snacks, and fruits and vegetables. Body mass index was measured by trained independent examiners.
Reduced Academic Achievement
Results revealed that every additional hour of television exposure at 29 months resulted in a 7% decrease in classroom engagement (95% confidence interval [CI], −0.02 to −0.004) and a 6% decrease in math achievement (95% CI, −0.03 to 0.01), as well as a 10% increase in victimization by classmates (95% CI, 0.01 – 0.05) in fourth grade.
Each additional hour of television viewing also resulted in a 13% decrease in time spent in physical activity (95% CI, 0.81 – 2.25) and a 9% decrease in activities that required physical effort (95% CI, −0.04 to 0). For every added hour they spent watching television in early childhood, those in the fourth grade had a 9% higher consumption of soft drinks (95% CI, 0 – 0.04), a 10% higher intake of sugary snacks (95% CI, 0 – 0.02), and a 5% increase in BMI (95% CI, 0.01 – 0.05).
The researchers controlled for a wide array of variables that could have influenced the study’s outcomes, including the child’s sex, temperament, behavior problems, and hours of sleep at 17 months of age. They also controlled for factors such as family makeup, family dysfunction, and maternal education during the same period.
“We’ve never seen this kind of statistical control in a study that assessed childhood television exposure,” Dr. Pagani said. She also noted that previous studies on the effects of television exposure have focused mostly on older children, and the duration between exposure and outcomes has been more short-lived than in the Canadian study.
The American Academy of Pediatrics recommends no television exposure during infancy and less than 2 hours per day beyond 2 years of age. However, the researchers found that television exposure among the children they studied ranged from a mean of 8.82 hours per week at 29 months to 14.85 hours per week at 53 months.
Although exposure to television at the age of 29 months provided the most striking evidence of its negative effects on later outcomes, preschool increases in exposure (at the age of 53 months) also contributed to developmental risks, Dr. Pagani said.
Sedentary Lifestyle — Mentally and Physically
“The study confirms that television exposure at a young age is a sedentary activity both on an intellectual level and on a physical level,” she said. She noted that children who spend too many hours in front of the television may not have the time or opportunity to develop skills for healthy social interaction. Too much television viewing also encourages unhealthy behaviors, such as snacking on sweets and lack of physical activity in young children — even if the programs are educational in nature.
“If you’re spending a lot of time in front of the TV, it’s not going to teach you how to problem solve, how to handle social situations, and how to stay mentally engaged in activities that require intellectual or physical effort,” she said.
“This study is an important advance in our understanding of the relationship between early television viewing and subsequent child development,” commented Frederick Zimmerman, PhD, chair and associate professor in the Department of Health Services at the UCLA School of Public Health, Los Angeles, California.
Dr. Zimmerman has studied the effects of different types of media exposure on developmental outcomes in childhood. “Parents should not take the results of this study for granted but should strive to limit the amount and type of television viewing they allow their children,” he told Medscape Psychiatry.
Dr. Zimmerman noted that an important limitation of the Canadian study was that it did not analyze the effects of different types of television content on later childhood development.
“Since we know from previous studies that content matters, the effects noted in this study would presumably be larger if we looked only at commercial content and smaller if we looked at educational content. Parents who feel they must rely on some TV can help themselves and their children by limiting their child’s viewing to high-quality educational shows,” he said.
The study was funded by Canada’s Social Science and Humanities Research Council International Collaboration Fund. Dr. Pagani and Dr. Zimmerman have disclosed no relevant financial relationships.
Arch Pediatr Adolesc Med. 2010;164:425-431