Early head injury and attention deficit hyperactivity disorder: retrospective cohort studyBMJ 2008; 337 doi: https://doi.org/10.1136/bmj.a1984 (Published 07 November 2008) Cite this as: BMJ 2008;337:a1984
- Heather T Keenan, associate professor1,
- Gillian C Hall, consultant2,
- Stephen W Marshall, associate professor 3
- 1Department of Pediatrics, University of Utah, Salt Lake City, UT 84158, USA
- 2Grimsdyke House, Ravenscroft Park, Barnet, Hertfordshire EN5 4ND
- 3Department of Epidemiology, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27699, USA
- Correspondence to: H T Keenan
- Accepted 8 September 2008
Objective To explore the hypothesis that medically attended head injury in young children may be causal in the later development of attention deficit hyperactivity disorder.
Design Retrospective cohort study.
Setting Health improvement network database (1988-2003), a longitudinal UK general practice dataset.
Participants All children registered in the database from birth until their 10th birthday.
Main outcome measures Risk of a child with a head injury before age 2 developing attention deficit hyperactivity disorder before age 10 compared with children with a burn injury before age 2 and children with neither a burn nor a head injury.
Results Of the 62 088 children who comprised the cohort, 2782 (4.5%) had a head injury and 1116 (1.8%) had a burn injury. The risk of diagnosis of attention deficit hyperactivity disorder before 10 years of age after adjustment for sex, prematurity, socioeconomic status, and practice identification number was similar in the head injury (relative risk 1.9, 95% confidence interval 1.5 to 2.5) and burn injury groups (1.7, 1.2 to 2.5) compared with all other children.
Discussion Medically attended head injury before 2 years of age does not seem to be causal in the development of attention deficit hyperactivity disorder. Medically attended injury before 2 years of age may be a marker for subsequent diagnosis of attention deficit hyperactivity disorder.
We thank Mary Thompson and the team from EPIC for providing the health improvement network data and the general practitioners for their continued support of the dataset.
Contributors: HTK designed the study, analysed the results, and wrote the manuscript. SWM assisted with the study design and analytical methods. GCH gave special insight into the use of the health improvement network data. HTK, SWM, and GCH all participated in the interpretation of the data, revised the manuscript critically for important intellectual content, and approved the version to be published. HTK is the guarantor.
Competing interests: None declared.
Ethical approval: Oxfordshire Multicentre Research Ethics Committee (ID# 06/Q1605/32) and the Institutional Review Board of the University of Utah gave approval for use of the health improvement network data.
Provenance and peer review: Not commissioned; externally peer reviewed.
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