Virginia Research Day 2025

Medical Student Research Clinical

02 IGF-1 as a Biomarker for Symptom Severity in Adult Traumatic Brain Injury: Evidence from an Observational Study

Justin Weppner, DO; Kimberly Rosenthal, MD; Varun Mishra, MSIII; Melissa Martinez, NP; Jennifer Bath, DNP; Tonja Locklear, PhD; Joshua Stodghill, DO Corresponding author: jlweppner@carilionclinic.org

Carilion Clinic Brain Injury Center Virginia Tech Carilion School of Medicine Eastern Virginia Medical School Edward Via College of Osteopathic Medicine Introduction: Traumatic brain injury (TBI)- related growth hormone deficiency is often undertreated, despite documented physical, metabolic, and neuropsychiatric effects. Insulin-like growth factor (IGF-1), with neuroreceptors located in brain regions responsible for learning, memory, and mood, regulates cerebral blood flow, neurogenesis, and neuroplasticity. Aim: To determine associations between IGF-1 levels and post-TBI symptom severity, anxiety, and depression. Design: This retrospective observational study at an Academic Brain Injury Center included participants evaluated 3-12 months post-TBI who had available IGF-1 values and complete RPQ-13,

GAD-7, and PHQ-9 responses. Patients under 18 or over 65 and those with incomplete questionnaires or missing IGF-1 values were excluded. Data extraction included questionnaire results recorded prior to IGF-1 blood draws. Patients were grouped by TBI severity: mild TBI (mTBI GCS 13-15) and moderate-to-severe TBI (msTBI GCS <13). IGF-1 Z-scores were used for age and gender standardization. Median Two-Sample and Fisher’s Exact Tests were used to compare mild (n=138) and moderate-to-severe (n=102) TBI groups. Kendall Tau correlations analyzed IGF-1 with RPQ-13, PHQ-9, and GAD-7 scores. Analyses were performed with SAS Enterprise Guide 8.3 with α=0.05 for significance. Results: Kendall Tau correlations were statistically significant (p<0.0001) and negative across all TBI severity groups; as IGF

1 Z-scores increased, RPQ-13, GAD-7, and PHQ-9 scores significantly decreased. A moderate, negative correlation between IGF-1 Z-scores and PHQ-9 (tau = -0.39, p<0.0001) and GAD-7 (tau = -0.47, p<0.0001) scores was observed for mTBI. In msTBI, a very strong, negative correlation between IGF-1 Z-scores and RPQ-13 scores (tau = -0.76, p<0.0001) was seen. Conclusion: Significant negative correlations were found between IGF-1 levels and RPQ-13, GAD-7, and PHQ-9 scores. Lower IGF-1 Z-scores correlated with higher TBI symptoms, depression, and anxiety, especially at Z-scores of -2 or below. Findings suggest that decreased IGF-1 is linked to increased post-injury symptom severity, depression, and anxiety. Future studies should explore IGF-1 as a biomarker for TBI symptom severity.

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