Tinnitus, or ringing in the ears even when it’s quiet, is the number one disability within the U.S. Veterans Administration, accounting for 10.5% of disability claims in 2017. Not to be dismissed as a minor nuisance, tinnitus produces effects such as irritability, sleep difficulty, anxiety, and depression; all symptoms characteristic of post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI). Indeed, Service members exposed to weapons-fire and explosive devices in theater often have one or more of TBI, PTSD, hearing loss, and tinnitus; however, no longitudinal study has identified predictors of tinnitus symptom maintenance, progression, or exacerbation.
In a recent publication in Military Medicine1, collaborators from Veterans Affairs (VA), University of California San Diego, and the VA Center of Excellence for Stress and Mental Health analyzed a subset of previously-recruited active-duty Marines from the longitudinal Marine Resiliency Study2. This all-male subset (N = 2,600; mean age = 23.3; 86.0% Caucasian) underwent extensive hearing, tinnitus, and mental health testing one month prior to a seven-month deployment to Iraq or Afghanistan, and were tested again at one week and three months after deployment. The study was designed to determine which clinical, demographic, or deployment-related variables predicted three-month post-deployment tinnitus progression (defined as new or worsening tinnitus symptoms).
Overall, 495 (19.0%) Marines had tinnitus prior to deployment. At three months after deployment, 706 (27.2%) experienced tinnitus, comprising 408 cases of new-onset tinnitus and 298 cases of ongoing tinnitus. Intuitively, pre-deployment tinnitus was the largest predictor of post-deployment onset or exacerbation of tinnitus. In fact, relative to those without pre-deployment tinnitus, Marines with constant tinnitus (i.e., continuous ear-ringing) prior to deployment were at far greater risk – nearly 30 times – of post-deployment tinnitus. Additionally, hearing loss, particularly of both high and low frequencies, increased post-deployment risk of tinnitus progression by a factor of almost six.
Additional clinical characteristics predicted post-deployment tinnitus symptom progression. Marines with PTSD symptoms were twice as likely to experience post-deployment tinnitus, and TBI enhanced tinnitus likelihood by a factor of 1.59. Notably, post-deployment tinnitus risk was magnified in Marines having experienced blast TBI (twice as likely) or moderate/severe TBI (by a factor of 2.57). Other descriptive elements such as Battalion alignment and rank did not significantly impact tinnitus outcome measures.
While this study cannot determine what causes tinnitus, predictive factors of tinnitus may allow for personalized and targeted protection of vulnerable Service members. Accordingly, treatments addressing tinnitus symptoms that overlap with coexisting PTSD or TBI symptoms can be tailored to maximize effectiveness and reduce cost.
1 Clifford RE, Baker D, Risbrough VB, Huang M, Yurgil KA. Impact of TBI, PTSD, and Hearing Loss on Tinnitus Progression in a US Marine Cohort. Military medicine. 2019.
2 Baker DG, Nash WP, Litz BT, et al. Predictors of risk and resilience for posttraumatic stress disorder among ground combat Marines: methods of the Marine Resiliency Study. Preventing chronic disease. 2012;9: E97.
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