PROJECT SUMMARY
There are nearly three million mild traumatic brain injuries (mTBIs) in the U.S. each year, and most occur in
patients less than 21 years of age. Clinical assessment of mTBI relies on symptom surveys that cannot
accurately predict the duration of symptoms or objectively identify brain recovery. A biologic test would allow
physicians to provide individualized recommendations for school and athletics participation, prescribe timely
pharmacologic treatments, or initiate early psychosocial services in patients at risk for persistent post-
concussion symptoms (PPCS). Non-coding ribonucleic acids (ncRNAs), such as microRNAs, are epi-
transcriptional molecules that are altered in patients with mTBI. They can be measured in peripheral biofluids
such as serum, or even saliva. Our previous research demonstrates that ncRNA changes in cerebrospinal fluid
are reflected in saliva, and that saliva ncRNA levels can predict PPCS. Validation of these findings in a large,
independent cohort could yield a biologic measure of PPCS risk (Aim 1), and guide individualized clinical
management decisions (Aim 2). This scientific premise forms the basis for our proposed multi-center study. We
will enroll 750 adolescents (ages 13-18 years) with mTBI, defined by the World Health Organization and Berlin
Consensus Criteria. We will measure levels of saliva ncRNAs enriched in neuronal and glial exosomes at
acute (<48 hours), sub-acute (7 days), and chronic (30 days) post-injury time points. PPCS will be defined by
persistence of ≥ 3 symptoms on day 30 (compared with pre-injury state, determined by the Post-Concussion
Symptom Inventory; PCSI). In 250 participants (training set), we will use a LASSO technique to refine a
multivariate model, that employs acute and sub-acute ncRNA levels, along with clinical, social, and
psychologic factors, to predict PPCS (while controlling for biologic covariates). Accuracy of the model will be
externally validated in the remaining 500 participants (test set). Sensitivity and specificity will be compared to
the validated “5P” clinical prediction tool. We will also examine the relationships between concussive symptom
phenotypes and ncRNA levels with a factor analysis and hierarchical clustering. In Aim 2, we will use LASSO
in a training set (n=250) to refine a second multivariate model, that uses acute and chronic ncRNA levels,
along with clinical, social, and psychologic factors to identify concussion recovery. Recovery will be defined by
self-report of “no difference from pre-injury” on the PCSI. Accuracy of the model will be externally validated in
the test set, and compared to the accuracy of reaction time performance across acute and chronic time points.
Our multi-disciplinary team includes experts in pediatrics, neurology, molecular biology, psychology, and
emergency medicine with a published track record of collaboration and the expertise necessary for this
proposal’s success. The study will yield an objective measure of PPCS risk, concussion phenotype, and
clinical recovery. When paired with medical, social, and psychologic assessments, this technology will allow
researchers to study mTBI therapies in biologically-defined patient subsets and personalize concussion care.