Hamza Yasmeen, Zeng Fan-Gang
Center for Hearing Research, Department of Anatomy and Neurobiology, Biomedical Engineering, Cognitive Sciences, Otolaryngology-Head and Neck Surgery, University of California, Irvine, Irvine, CA, United States.
Front Neurosci. 2021 Oct 28;15:735950. doi: 10.3389/fnins.2021.735950. eCollection 2021.
Because hearing loss is a high-risk factor for cognitive decline, tinnitus, a comorbid condition of hearing loss, is often presumed to impair cognition. The present cross-sectional study aimed to delineate the interaction of tinnitus and cognition in the elderly with and without hearing loss after adjusting for covariates in race, age, sex, education, pure tone average, hearing aids, and physical well-being. Participants included 643 adults (60-69 years old; 51.3% females) from the National Health and Nutrition Examination Survey (NHANES, 2011-2012), and 1,716 (60-69 years old; 60.4% females) from the Hispanic Community Health Study (HCHS, 2008-2011). Multivariable linear and binary logistic regression was used to assess the association between tinnitus and cognition in the two sub-cohorts of normal hearing (NHANES, = 508; HCHS, = 1264) and hearing loss (NHANES, = 135; HCHS, = 453). Cognitive performance was measured as a composite z-score from four cognitive tests: The Consortium to Establish a Registry for Alzheimer's Disease (CERAD)-word learning, CERAD-animal fluency, CERAD-word list recall, and the digit symbol substitution test (DSST) in NHANES, and a comparable Hispanic version of these four tests in HCHS. Multivariable linear regression revealed no association between tinnitus and cognition, except for the NHANES (non-Hispanic) participants with hearing loss, where the presence of tinnitus was associated with improved cognitive performance (Mean = 0.3; 95% CI, 0.1-0.5; , 0.018). Using the 25th percentile score of the control (i.e., normal hearing and no tinnitus) as a threshold for poor cognitive performance, the absence of tinnitus increased the risk for poor cognitive performance (OR = 5.6, 95% CI, 1.9-17.2; , 0.002). Sensitivity analysis found a positive correlation between tinnitus duration and cognitive performance in the NHANES cohort [(4,140), 2.6; , 0.037]. The present study finds no evidence for the assumption that tinnitus impairs cognitive performance in the elderly. On the contrary, tinnitus is associated with improved cognitive performance in the non-Hispanic elderly with hearing loss. The present result suggests that race be considered as an important and relevant factor in the experimental design of tinnitus research. Future longitudinal and imaging studies are needed to validate the present findings and understand their mechanisms.
由于听力损失是认知衰退的高风险因素，耳鸣作为听力损失的一种共病情况，常被认为会损害认知。本横断面研究旨在在对种族、年龄、性别、教育程度、纯音平均值、助听器使用情况和身体健康状况等协变量进行调整后，描绘有无听力损失的老年人中耳鸣与认知之间的相互作用。参与者包括来自美国国家健康与营养检查调查（NHANES，2011 - 2012年）的643名成年人（60 - 69岁；51.3%为女性），以及来自西班牙裔社区健康研究（HCHS，2008 - 2011年）的1716名成年人（60 - 69岁；60.4%为女性）。多变量线性和二元逻辑回归用于评估正常听力亚组（NHANES，n = 508；HCHS，n = 1264）和听力损失亚组（NHANES，n = 135；HCHS，n = 453）中耳鸣与认知之间的关联。认知表现通过四项认知测试的综合z分数来衡量：在NHANES中为阿尔茨海默病注册协会（CERAD）单词学习、CERAD动物流畅性、CERAD单词列表回忆和数字符号替换测试（DSST），在HCHS中为这四项测试的可比西班牙裔版本。多变量线性回归显示耳鸣与认知之间无关联，但在NHANES（非西班牙裔）有听力损失的参与者中除外，在这些参与者中耳鸣的存在与认知表现改善相关（均值 = 0.3；95%可信区间，0.1 - 0.5；P = 0.018）。以对照组（即正常听力且无耳鸣）的第25百分位数分数作为认知表现不佳的阈值，无耳鸣会增加认知表现不佳的风险（比值比 = 5.6，95%可信区间，1.9 - 17.2；P = 0.002）。敏感性分析发现NHANES队列中耳鸣持续时间与认知表现呈正相关[（4140），2.6；P = 0.037]。本研究没有发现证据支持耳鸣会损害老年人认知表现这一假设。相反，在有听力损失的非西班牙裔老年人中，耳鸣与认知表现改善相关。目前的结果表明，在耳鸣研究的实验设计中应将种族视为一个重要且相关的因素。未来需要进行纵向和影像学研究来验证目前的发现并了解其机制。
