Wednesday, April 17, 2024
4/17/2024
PROJECT SUMMARY/ABSTRACT Subconcussive head impacts (SHI), defined as an impact that does not trigger clinically detectable concussion symptoms, are incredibly common among the nearly 3 million youth and college athletes in contact sports, who incur an average of 400 to 650 SHI per season from, for example, soccer headings and football tackles. Our preliminary data coupled with the recent concussion literature suggest that individuals with attention- deficit/hyperactivity disorder (ADHD) may have a heightened vulnerability to SHI. Approximately 6.5% to 10.1% of contact-sport athletes are diagnosed with and treated for ADHD. Our data show that when ADHD individuals experience 10 acute controlled soccer headings, their verbal and visual memory functions are significantly impaired in a series of follow-up time points, whereas non-ADHD individuals are not significantly affected by 10 headings. If this is true, ADHD may be a predisposing factor to chronic neurological deficits from SHI. However, our knowledge regarding the interaction between ADHD and SHI is limited to our preliminary data. Therefore, the proposed study aims to delineate ADHD individuals’ neural responses to SHI by using neural-injury blood biomarkers and functional and diffusion MRI techniques. The overall goal of this study is to identify a panel of fluid and imaging biomarkers that can reflect subtle and subclinical, but detectable, levels of neuronal damage in individuals with ADHD. The panel of biomarkers will be useful in a future longitudinal field study to track ADHD athletes’ exposure to SHI and long-term neurological outcomes. Our central hypothesis is that SHI from 10 acute controlled soccer headings will induce neuronal structural and functional impairments in both ADHD and non- ADHD individuals, but the degree of impairments will be greater in ADHD individuals than in non-ADHD individuals. This hypothesis is substantiated by three specific aims: (1) To assess neuronal, axonal, and astroglia damage through the response profile of blood biomarkers (NF-L, Tau, UCH-L1, GFAP) in ADHD and non-ADHD individuals after repetitive SHI; (2) To identify regional changes in fMRI activation during memory and attention tasks in ADHD and non-ADHD individuals after repetitive SHI; (3) To examine changes in axonal microstructural integrity in ADHD and non-ADHD individuals after repetitive SHI using diffusion tensor imaging and neurite- orientation dispersion and density imaging. The clinical implications of the study include: (i) Providing evidence of ADHD-specific responses to acute SHI; (ii) Informing clinicians that athletes with ADHD may require personalized safety protocols with periodic cognitive assessments; and (iii) Generating a well-controlled, multimodal dataset for a future longitudinal study to test long-term effects of SHI in athletes with ADHD.
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