Increased risk of psychiatric disorder in patients with hearing loss: a nationwide population-based cohort study.

BACKGROUND: Hearing loss has been shown to be a risk factor for psychiatric disorders. In addition, long-term hearing loss is associated with increased hospitalization and mortality rates; however, the increased risk and duration of effect of hearing loss in combination with other chronic diseases on each psychiatric disorder are still not clearly defined. The purpose of this article is to clarify the risk of hearing loss for each disorder over time. METHODS: This was a retrospective cohort study, and a national health insurance research database in Taiwan was utilized. All (n = 1,949,101) Taiwanese residents who had a medical visit between 2000 and 2015 were included. Patients with hearing loss and a comparative retrospective cohort were analyzed. Every subject was tracked individually from their index date to identify the subjects who later received a diagnosis of a psychiatric disorder. The Kaplan‒Meier method was used to analyze the cumulative incidence of psychiatric disorders. Cox regression analysis was performed to identify the risk of psychiatric disorders. RESULTS: A total of 13,341 (15.42%) and 31,250 (9.03%) patients with and without hearing loss, respectively, were diagnosed with psychiatric disorders (P < 0.001). Multivariate analysis indicated that hearing loss significantly elevated the risk of psychiatric disorders (adjusted HR = 2.587, 95% CI 1.723-3.346, p < 0.001). CONCLUSION: Our findings indicate that patients with hearing loss are more likely to develop psychiatric disorders. Furthermore, the various psychiatric disorders are more likely to occur at different times. Our findings have important clinical implications, including a need for clinicians to implement early intervention for hearing loss and to pay close attention to patients' psychological status. Trial registration TSGHIRB No. E202216036.

C-Phycocyanin Attenuates Noise-Induced Cochlear Synaptopathy via the Inhibition of Oxidative Stress and Intercellular Adhesion Molecule-1 in the Cochlea.

The synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) are the most vulnerable structures in the noise-exposed cochlea. Cochlear synaptopathy results from the disruption of these synapses following noise exposure and is considered the main cause of poor speech understanding in noisy environments, even when audiogram results are normal. Cochlear synaptopathy leads to the degeneration of SGNs if damaged IHC-SGN synapses are not promptly recovered. Oxidative stress plays a central role in the pathogenesis of cochlear synaptopathy. C-Phycocyanin (C-PC) has antioxidant and anti-inflammatory activities and is widely utilized in the food and drug industry. However, the effect of the C-PC on noise-induced cochlear damage is unknown. We first investigated the therapeutic effect of C-PC on noise-induced cochlear synaptopathy. In vitro experiments revealed that C-PC reduced the H2O2-induced generation of reactive oxygen species in HEI-OC1 auditory cells. H2O2-induced cytotoxicity in HEI-OC1 cells was reduced with C-PC treatment. After white noise exposure for 3 h at a sound pressure of 118 dB, the guinea pigs intratympanically administered 5 µg/mL C-PC exhibited greater wave I amplitudes in the auditory brainstem response, more IHC synaptic ribbons and more IHC-SGN synapses according to microscopic analysis than the saline-treated guinea pigs. Furthermore, the group treated with C-PC had less intense 4-hydroxynonenal and intercellular adhesion molecule-1 staining in the cochlea compared with the saline group. Our results suggest that C-PC improves cochlear synaptopathy by inhibiting noise-induced oxidative stress and the inflammatory response in the cochlea.