Using sympathetic nervous system responses to evaluate distressing tinnitus: a pupillometry and skin conductance feasibility study.

Objective. There is no universal measure of tinnitus apart from subjective reports. Therefore, to improve Veteran health and wellbeing, it is crucial that objective tools be developed that distinguish between the presence of tinnitus and tinnitus distress. Tinnitus distress is a high impact area of study in

Veterans because tinnitus is consistently the most-common service-connected disability. The Cognitive Behavioral Model of Tinnitus Distress predicts that one of the proposed mechanisms behind tinnitus distress is that it increases the cognitive demands on the listener, which interfere with their ability to

concentrate. The application of cognitive resources towards a listening task is commonly referred to as listening effort. Increased listening effort increases sympathetic nervous system activity, and pupillometry can reliably capture these changes. The Cognitive Behavioral Model of Tinnitus Distress

asserts that bothersome tinnitus increases arousal and distress, which also increase sympathetic nervous system activity. Skin conductance measurements reliably increase when participants view or listen to arousing images and sounds; they also covary with pupil responses. Therefore, this proposal will use pupillometry and skin conductance to explore how distressing tinnitus alters listening effort and

affective processing. Design. The proposed study will employ a cross-sectional design and quantify sympathetic nervous system activity that has been associated with listening effort and affective processing. Adult Veterans and non-Veterans will be recruited and grouped into one of three categories: 1) adult controls without

hearing loss or distressing tinnitus, 2) adults with hearing loss but not distressing tinnitus, 3) adults with hearing loss and distressing tinnitus. Methods. Participants will listen to sentences, view affective images, and listen to affective sounds. Pupillometry and skin conductance responses will be simultaneously recorded for all stimuli. These

methods will be used to address the following aims: Aim 1: Quantify the “selective monitoring and attention” component of the Cognitive-Behavioral Model of Tinnitus Distress by assessing listening effort in Veterans with and without distressing tinnitus. The working hypothesis is that distressing tinnitus is associated with increased listening effort.

Participants with tinnitus distress will exhibit larger pupil dilations while listening to sentences, particularly in quiet, compared to adults without tinnitus distress. Skin conductance responses are not anticipated to be sensitive to listening effort. Aim 2: Quantify the “arousal and distress” component of the Cognitive-Behavioral Model of

Tinnitus Distress by assessing physiological responses to affective visual and auditory stimuli in Veterans with and without distressing tinnitus. The working hypothesis is that distressing tinnitus is associated with amplified physiological responses to affective auditory and visual stimuli. Participants

with tinnitus distress will exhibit larger pupil dilations and covarying skin conductance responses to affective stimuli compared to adults without tinnitus distress. The rationale for these aims is that they will lead to the development of high impact tools that will allow future research to 1) objectively measure therapeutics designed to reduce tinnitus distress and 2)

examine how different comorbidities such as blast exposure, TBI, and PTSD affect tinnitus distress.