Background: Tinnitus is common among veterans with blast exposure and associated with an increase in severity and diagnosis of anxiety, depression, sleep disturbances and chronic pain. While questions regarding the neurobiological basis of tinnitus remain, current models suggest critical roles for non-auditory networks related to the attentional, emotional, and perceptual processes of the condition. This study sought to determine whether changes in resting state functional connectivity associated with tinnitus are independent from common comorbidities.
Methods: A sample of 255 post-9/11 veterans (56% with tinnitus) were included in the study. Tinnitus status, combat exposure, sleep quality, pain, and clinical interviews for psychological, mood, and TBI assessments were gathered from each subject. Subjects also completed two resting-state scans which were concatenated and preprocessed. ROIs were assigned to one of 13 networks. Functional connectivity density (FCD) was then calculated as a global measure of connectivity.
Results: Analyses showed that those with tinnitus exhibited reduced global connectivity compared to those without tinnitus (t(253)=3.05, p=0.0025). Findings also suggest that there are global network-level decreases in FCD within somatosensory, cingulo-opercular, auditory, and default-mode networks as well as decreases in between-network FCD for the auditory, cerebellar, default-mode networks, and ventral attention networks. Importantly, multiple linear regression showed that mean FCD is associated with the tinnitus condition (t=-3.66, p<0.001) when PTSD, depression, anxiety, sleep and pain are included as covariates.
Conclusion: The current results suggest that widespread decreases in FCD occur in those with tinnitus and that cerebellar connectivity may play a crucial role in the condition. Notably, the effects of tinnitus on FCD in this sample of veterans also appear to be independent of common psychiatric, behavioral, and neurological conditions.
Live Zoom Session – March 9th
Francesca C. Fortenbaugh, PhD, Julia M. Brau, BA, Michael Esterman, PhD, Jennifer R. Fonda, PhD, Catherine Fortier, PhD, William Milberg, PhD, Regina E. McGlinchey, PhD
Francesca Fortenbaugh, PhD