Larger auditory brainstem responses in chronic tinnitus patients with higher levels of anxiety and tinnitus distress

• Auditory brainstem responses (ABRs) were larger in chronic tinnitus patients with higher psychological distress levels. • ABR amplitudes were predicted by anxiety levels, sex, hyperacusis, and ABR measurement system, but neither hearing loss nor age. • These results question the common assumption that ABRs are independent of the psychological state of the subject being tested. The click-evoked auditory brainstem response (ABR) is a standard diagnostic tool for assessing the lower auditory pathways. However, the factors that determine the ABR amplitudes are poorly understood, particularly in the context of chronic tinnitus. Here, we tested the hypothesis that psychological distress, which is often very high among chronic tinnitus patients, acts as gain factor of the ABR. We used a large, multivariate clinical dataset (N = 149) comprising ABR recordings, hearing- and tinnitus-related audiometric measures, sociodemographic and health-related information, as well as psychometric questionnaires scores to identify variables that affect the ABR amplitudes. Significant positive correlations between ABR amplitudes and psychological distress levels (anxiety and tinnitus distress) were observed throughout. Stepwise-selected regression modelling moreover showed that the anxiety level (i.e., HADS A scores) was a significant predictor of the ABR wave I, III, and V amplitudes. Additionally, wave III and V amplitudes were smaller in male patients and wave V amplitudes were larger in patients with additional hyperacusis, while no effects of age and hearing loss were found. Even at the level of the brainstem, psychometric data proved important for explaining auditory-evoked electrophysiological responses in patients with chronic tinnitus. These results question the common assumption that ABRs represent a purely objective measure of auditory functioning.