PEDIATRICS Vol. 114 No. 5 November 2004, pp. 1372-1373 (doi:10.1542/peds.2004-0954)
Does Children's Watching of Television Cause Attention Problems? Retesting the Hypothesis in a Danish Cohort
Carsten Obel, MD, PhDPerinatal Epidemiological Research Unit
Department of Obstetrics and Pediatrics
Aarhus University Hospital
8200 Aarhus N, Denmark
Danish Epidemiological Science Centre
Department of Epidemiology and Social Medicine
Aarhus University
8000 Aarhus C, Denmark
Tine Brink Henriksen, MD, PhD
Perinatal Epidemiological Research Unit
Department of Obstetrics and Pediatrics
Aarhus University Hospital
8200 Aarhus N, Denmark
Søren Dalsgaard, MD, PhD
Psychiatric Hospital for Children and Adolescents
Aarhus University Hospital
8240 Risskov, Denmark
Karen Markussen Linnet, MD
Perinatal Epidemiological Research Unit
Department of Obstetrics and Pediatrics
Aarhus University Hospital
8200 Aarhus N, Denmark
Elisabeth Skajaa, RN
Perinatal Epidemiological Research Unit
Department of Obstetrics and Pediatrics
Aarhus University Hospital
8200 Aarhus N, Denmark
Per Hove Thomsen, MD, DMSC
Psychiatric Hospital for Children and Adolescents
Aarhus University Hospital
8240 Risskov, Denmark
Jørn Olsen, MD, PhD
Danish Epidemiological Science Centre
Department of Epidemiology and Social Medicine
Aarhus University
8000 Aarhus C, Denmark
To the Editor.
In a recent issue of Pediatrics, Christakis et al1 reported an association between the number of hours of watching television close to 2 and 4 years and parents' report on their children's behavior in early school age.
Based on the findings, the authors suggest that we generally limit young children's television use. This is probably a good idea, but we question whether this report creates additional evidence for this advice.
The authors reported a 9% increase in risk of attention problems for each daily hour of television-watching. The measure of adverse behavior was based on a score of maternal report of child behavior including restlessness, concentration problems, impulsiveness, confusion, and obsession. A similar association was found at both ages of reported television-watching, which would be unexpected if the association was caused by an influence on brain development.
A log-linear association is anticipated, but whether such a relationship is actually present in the data is obscure. This particular strategy of analysis may provide more statistical power, but the assumption of a log-linear association is strong and implies that any additional hour of watching television provides the same log-linear increase in risk, whereas a threshold effect or other nonequidistant associations may very likely be present.
We retested the hypothesis in a part of the Aarhus Birth Cohort, which consists of all children born from 1990 at the Aarhus University Hospital, Denmark. As part of a follow-up program for children born in 1991–1992 and examined at 8 months of age,2 participating mothers were asked about their child's television-watching on the day previous to completion of the questionnaire when children were 31/2 years old. The relevant child behavior at that age was evaluated by a questionnaire developed for preschoolers by Behar3 based on the Rutter scale.
The behavior of the children was evaluated further at the age of 10 to 11 years by the mother using an "ADHD [attention-deficit/hyperactivity disorder] problem score" based on a selection of 12 questions from the Child Behavior Checklist4 identified by their relation to the ADHD diagnosis in a previous Danish study.5 The following year, teachers and parents filled in the Strength and Difficulties Questionnaire,6 and their reports were summarized to identify probable and likely ADHD cases.7
We found no significant association between hours of watching television and behavioral problems in any of the age groups, although the results do not rule out such an effect, especially not for those who spend the longest time in front of the television (Table 1).
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US children apparently watch much more television than Danish children, and if there is a threshold level for effect, we may not be able to detect an association. Our data indicate that a threshold for no effect may exist.
It is a clinical experience that watching television can engage children with ADHD for some time, probably because of the constant visual and auditory stimuli they receive from these media. The parents of these children may therefore be more likely to allow them to watch television for longer periods of time. The children in our study, who were watching >11/2 hour of television at the age of 31/2 years, were more likely to have ADHD-like behavior already at this age. The direction of causality may very well be the opposite of what is concluded by Christakis et al.
We cannot exclude the possibility that watching television in childhood may cause behavioral problems, but we need better studies to further elucidate this association.
REFERENCES
1. Christakis DA, Zimmerman FJ, DiGiuseppe DL, McCarty CA. Early television exposure and subsequent attentional problems in children.
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2. Obel C, Henriksen TB, Hedegaard M, Secher NJ, Ostergaard J. Smoking during pregnancy and babbling abilities of the 8-month- old infant. Paediatr Perinat Epidemiol. 1998;12 :37 –48[CrossRef][Web of Science][Medline]
3. Behar LB. The Preschool Behavior Questionnaire. J Abnorm Child Psychol. 1977;5 :265 –275[CrossRef][Web of Science][Medline]
4. Achenbach TM. Manual for the Child Behaviour Checklist/4-18 and 1991 Profile. Burlington, VT: University of Vermont; 1993
5. Bilenberg N. The Child Behavior Checklist (CBCL) and related material: standardization and validation in Danish population based and clinically based samples. Acta Psychiatr Scand Suppl. 1999;398 :2 –52[Medline]
6. Goodman R. The Strengths and Difficulties Questionnaire: a research note. J Child Psychol Psychiatry. 1997;38 :581 –586[Web of Science][Medline]
7. Goodman R, Ford T, Simmons H, Gatward R, Meltzer H. Using the Strengths and Difficulties Questionnaire (SDQ) to screen for child psychiatric disorders in a community sample.
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PEDIATRICS (ISSN 1098-4275). ©2004 by the American Academy of Pediatrics
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