Study: ADHD May Diminish Brain Tolerance to Subconcussive Head Impacts
Repetitive subconcussive head impacts, or hits to the head that don’t result in overt concussion symptoms, may be more harmful to the brains of individuals with ADHD than they are to brains of those without the disorder.
November 13, 2020
Brain tolerance to repetitive subconcussive head impacts may be diminished by attention deficit hyperactivity disorder (ADHD or ADD), according to a study of soccer players recently published in the Journal of Attention Disorders.1 In high school and college athletes, ADHD increases the risk for concussion, “accompanied by amplified concussion symptoms, prolonged recovery, and impaired performance on working memory tasks.”2 The majority of college athletes with ADHD participate in contact sports, where they can “sustain several hundred to a thousand subconcussive head impacts per season.”3 Subconcussive head impacts are defined as hits to the head that don’t result in overt concussion symptoms.
Researchers conducted a case-control intervention study of 51 adults with ADHD who had at least 5 years of soccer heading experience, and a control cohort of similar athletes without ADHD. Cognitive assessment, using ImPACT, and plasma levels of neurofilament-light, Tau, glial-fibrillary-acidic protein (GFAP), and ubiquitin-C-terminal hydrolase-L1 (UCH-L1) were measured. Among the main findings were:
- Researchers observed a higher degree of impairment in verbal memory function among participants with ADHD following 10 soccer headings
- All domains of cognitive functions in participants without ADHD were able to tolerate 10 soccer headings
- Plasma GFAP (a protein released only after cell death or injury) and UCH-L1 levels were acutely elevated after soccer headings endured by participants with ADHD only
- Acute elevations of GFAP after soccer headings were correlated to acute verbal memory declines in the ADHD group
Though the study did not make any diagnostic claim of concussive or subconcussive injury after 10 soccer headings, the evidence was enough to lead researchers to conclude that ADHD may cause reduced tolerance to acute subconcussive head impacts.
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1Nowak MK, Ejima K, Quinn PD, et al. ADHD May Associate With Reduced Tolerance to Acute Subconcussive Head Impacts: A Pilot Case-Control Intervention Study. Journal of Attention Disorders. November 2020. doi:10.1177/1087054720969977
2Biederman, J., Feinberg, L., Chan, J., Adeyemo, B. O., Woodworth, K. Y., Panis, W., McGrath, N., Bhatnagar, S., Spencer, T. J., Uchida, M., Kenworthy, T., Grossman, R., Zafonte, R., Faraone, S. V. (2015). Mild traumatic brain injury and attention-deficit hyperactivity disorder in young student athletes. Journal of Nervous & Mental Disease, 203(11), 813−819. https://doi.org/10.1097/NMD.0000000000000375
3Bailes, J. E., Petraglia, A. L., Omalu, B. I., Nauman, E., Talavage, T. (2013). Role of subconcussion in repetitive mild traumatic brain injury. Journal of Neurosurgery, 119(5), 1235−1245. https://doi.org/10.3171/2013.7.JNS121822