Neurobiological Similarities of Tinnitus and PTSD

Tinnitus and posttraumatic stress disorder (PTSD) are two of the most common service-connected disabilities for active-duty Service Members and Veterans. Tinnitus and PTSD are highly co-morbid, yet distinct disorders. Tinnitus is an auditory disorder in which an illusory auditory percept is experienced, usually as ringing, buzzing, or whooshing sounds, despite no external objective noise source. On the other hand, PTSD is a trauma-related disorder, and is identified by intrusions of the traumatic event, avoidance of reminders, negative alterations in cognition and mood, and hypervigilance or hyperarousal. Similarities between tinnitus and PTSD have been documented among Cambodian refugees, as well as among U.S. Veteran samples. Moreover, the latest neuroimaging data from a recent clinical trial indicated that the auditory-vigilance network was the most dysregulated among active-duty service members with PTSD, compared to combat controls and civilian controls. Due to similar symptoms between tinnitus-related distress and PTSD, and similar dysregulated resting-state brain networks, it remains important to more fully understand how these two distinct disorders may be related. This study will be the first to prospectively examine the overt emotional, behavioral, and cognitive symptoms related to tinnitus-related distress and PTSD, and the overlapping functional connectivity between tinnitus and PTSD. Investigators will examine the overlapping symptoms and neurobiological mechanisms by conducting audiometric and psychological assessments and resting-state functional magnetic resonance imaging (fMRI) among 120 participants (30 with tinnitus and PTSD, 30 with only PTSD, 30 with only tinnitus, and 30 healthy controls). Participants will be recruited from the Frank Tejeda PTSD Clinic and the Audiology Clinic within the South Texas VA Health Care System, and the Hearing Center of Excellence at Lackland Air Force Base. Canonical correlations will be conducted to examine the symptom overlap between tinnitus and PTSD (Aim 1). Investigators aim to neurobiologically characterize tinnitus and PTSD, both separately and conjointly, by conducting fMRI (Aim 2). Investigators also aim to apply modeling to psychometric and neurofunctional data to identify specific regions of the auditory-vigilance network associated with distress related to tinnitus and PTSD. Understanding the shared cognitive, emotional, and behavioral symptoms and neurobiology associated with tinnitus and PTSD will help clinicians and researchers fully understand tinnitus and PTSD independently and conjointly. Results will lead to the identification of neurobiological markers for tinnitus and PTSD, identification of a different phenotype for individuals with both conditions, and development of behavioral and neuro-modulatory therapies that can reduce distress and impairment.