PP1309 - Reactivity to Stress and Noise in Tinnitus Depends on Psychological Profile and Tinnitus Duration

Abstract:
This study investigates the interactions between autonomic reactivity and psychological traits in tinnitus individuals, with the hypothesis that autonomic plasticity occurs as tinnitus becomes chronic. Adults with acute and chronic tinnitus and controls without tinnitus were exposed to stress and noise while recording electrocardiographic and electrodermal activity. Tinnitus groups were hyporeactive to stress but hyperreactive to noise compared to controls. Tinnitus distress, hyperacusis, and coping strategies influenced autonomic responses differently depending on tinnitus duration. Autonomic activation was related to changes in tinnitus perception. This study is the first to explore relationships between autonomic activity, tinnitus duration, and psychological traits.

Summary:
Rationale
Tinnitus individuals often report changes in tinnitus perception when exposed to stress or noise. The autonomic nervous system (ANS), which regulates stress responses, is thought to show plastic changes in these individuals. The present study investigates autonomic activity during acute stress and noise exposure, with the hypothesis that autonomic plasticity occurs as tinnitus becomes chronic. The influence of some psychological factors on autonomic reactivity was also investigated.

Design
Participants with Acute ( < 6 months) and Chronic ( > 3 years) tinnitus and Matched Controls were exposed to a stress (mental calculation) and a noise (low frequency broadband noise) task. Electrodermal and cardiac activity were continuously recorded to extract skin conductance level (SCL) and heart rate variability (HRV), robust biomarkers of sympathetic and parasympathetic activity. Psychological traits were assessed using validated questionnaires for perceived stress (PSS), coping strategies (BRIEF-Cope), tinnitus severity (TFI) and hyperacusis (HQ). Stress responses were analyzed by segmenting signals in 30-s time windows. Linear mixed effects models were used to determine effects of groups and time on physiological responses and Pearson correlations between questionnaire scores and physiological data were run.

Results
Autonomic biomarkers changed dynamically over time. Compared to Controls, both tinnitus groups showed blunted responses for both SCL and HRV during the arithmetic task, but enhanced SCL in response to noise, indicating maladaptive autonomic responses related to the presence of tinnitus. Notably, the Acute group showed the highest maladaptive responses in both tasks compared to the two other groups, suggesting progressive autonomic adaptation as tinnitus becomes chronic. In the Acute group, lower (maladaptive) reactivity to mental stress was associated with higher hyperacusis scores (r= -.60), and higher (maladaptive) reactivity to noise to lower coping abilities (r= -.63), greater hyperacusis (r= .49). Those with higher tinnitus distress showed lower reactivity to noise (r= -.78). In the Chronic group, no factor influenced responses to noise, but lower responses during mental stress were associated with greater tinnitus severity (r= -.49).

Conclusions
This is the first study to investigate autonomic activity during noise and stress exposure, taking into account the duration of tinnitus. The main finding is that both tinnitus groups were hypo-reactive to stress and hyper-reactive to noise compared to Controls, suggesting autonomic dysregulation related to the presence of tinnitus. In addition, individuals with Acute tinnitus showed higher maladaptive responses during both noise and mental stress than those with Chronic tinnitus. This suggests that ANS perceives noise stimuli as more threatening in the early stages after tinnitus onset, overall suggesting autonomic adaptation as tinnitus progresses. Tinnitus severity, coping strategies and hyperacusis levels were correlated to autonomic reactivity and differentially affected by tinnitus duration. This study is an important step towards understanding the role of stress in the transition from acute to chronic tinnitus and highlights the importance of early assessment and intervention.