Objective To investigate associations between concussion and the risk of follow-up diagnoses of attention-deficit hyperactivity disorder (ADHD), mood and anxiety disorders (MADs), dementia and Parkinson’s disease.
Design A retrospective population-based cohort study.
Setting Administrative health data for the Province of Manitoba between 1990–1991 and 2014–2015.
Participants A total of 47 483 individuals were diagnosed with a concussion using International Classification of Diseases (ICD) codes (ICD-9-CM: 850; ICD-10-CA: S06.0). All concussed subjects were matched with healthy controls at a 3:1 ratio based on age, sex and geographical location. Associations between concussion and conditions of interest diagnosed later in life were assessed using a stratified Cox proportional hazards regression model, with adjustments for socioeconomic status and pre-existing medical conditions.
Results 28 021 men (mean age ±SD, 25±18 years) and 19 462 women (30±21 years) were included in the concussion group, while 81 871 men (25±18 years) and 57 159 women (30±21 years) were included in the matched control group. Concussion was associated with adjusted hazard ratios of 1.39 (95% CI 1.32 to 1.46, p<0.001) for ADHD, 1.72 (95% CI 1.69 to 1.76; p<0.001) for MADs, 1.72 (95% CI 1.61 to 1.84; p<0.001) for dementia and 1.57 (95% CI 1.41 to 1.75; p<0.001) for Parkinson’s disease.
Conclusion Concussion was associated with an increased risk of diagnosis for all four conditions of interest later in life.
- public health
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Contributors Concept and design: MPM, JRSL, HJP, JW. Acquisition, analysis or interpretation of data: MPM, JRSL, HJP, RBT. Drafting of manuscript: MPM, JRSL, HJP, RBT, JW. Critical revision of the manuscript for important intellectual content: MPM, JRSL, HJP, RBT, JW. Statistical analysis: MPM, JRSL, HJP, RBT. Obtained funding: JW, JRSL. Administrative, technical or material support: HJP, JRSL. Supervision: JRSL, JW.
Funding This study was funded by the Pan Am Clinic Foundation. MPM was supported by a Canadian Institutes of Health Research Frederick Banting and Charles Best Canada Graduate Scholarship.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethical approval was obtained from the University of Manitoba Research Ethics Board (H2013:402), the Health Information Privacy Committee (#2015/2016-50), the Winnipeg Regional Health Authority and the Manitoba Centre for Health Policy (#2016-014).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. De-identified population-based administrative health data were accessed through the Manitoba Population Research Data Repository. Access to this repository is managed by the Manitoba Centre for Health Policy. More information can be found here: http://umanitoba.ca/faculties/health_sciences/medicine/units/chs/departmental_units/mchp/resources/access.html.
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