Relationships between vestibular dysfunction and cognitive performance in military veterans with mild to moderate TBI

Objective: Vestibular dysfunction is common following mild-to-moderate traumatic brain injury (TBI) and impacts quality of life. However, little is known regarding the persistence and stability of vestibular symptoms over time and their effects on cognition. This study examined self-reported vestibular symptoms 1 to 2 years following mild-to-moderate TBI in a Military/Veteran cohort. We further evaluated the association of vestibular symptoms with 5-year post-TBI cognitive outcomes. Method: Military service members and Veterans enrolled in the VA TBI Model Systems (TBIMS) completed follow-up interviews at 1-, 2-, and 5-years post-TBI, with valid symptom and performance validity. Study 1 examined vestibular symptom change from 1 to 2 years with the Neurobehavioral Symptom Inventory (N = 76). Study 2 examined the association between year 2 vestibular symptoms and year 5 cognitive performance on Brief Test of Adult Cognition by Telephone (BTACT), controlling for demographics, posttraumatic amnesia duration, and mood symptoms (N = 67). Results: Vestibular symptoms were stable between 1- and 2-year follow-up (88% with no reliable change, 63% with disruptive vestibular symptoms at both time points). Year 2 vestibular symptoms did not predict year 5 BTACT Verbal Memory or Executive Function composites after controlling for covariates. Older age and greater depression symptoms predicted worse executive function. Conclusions: Although vestibular symptoms did not predict cognitive performance, we describe chronic disruptive vestibular symptoms and mood effects on executive functioning for years following mild-to-moderate TBI. Despite study limitations, large effect size differences between TBI-severity groups warrants further exploration to potentially mitigate influence of persistent vestibular symptoms on health outcomes.