Comorbidity of Chronic Tinnitus and Psychological Stress - Which Came First, the Chicken or the Egg?

Subjective tinnitus is a frequent, debilitating hearing disorder causing severe emotional stress and psychological suffering. Likewise, many reports show that the onset of tinnitus occurs at the time of high stress or after a period of stress. It is also common for existing tinnitus to become worse during exposure to stress. However, in clinical practice the association between tinnitus and stress is often neglected. Extensive search of the Web of Science database has shown a low ratio of scientific articles about coexistence of stress and tinnitus compared to other stress-related conditions. Specifically, there are about sixteen times more articles investigating comorbid stress in chronic pain, about six times more in chronic fatigue, and about four times more in fibromyalgia. Previous studies of biological markers of stress in tinnitus patients showed normal diurnal levels of stress hormone cortisol. However, experimental studies of tinnitus subjects showed a blunted reactive cortisol response after a psychosocial stress test, exposure to noise in the laboratory and a dexamethasone suppression test. In addition, tinnitus subjects showed increased sympathetic tone, and weakened sympathetic response after exposure to mental arithmetic task. In tinnitus subjects oxidative metabolism shows imbalance with shift from antioxidant enzyme preponderance towards oxidative stress predominance. Relaxation therapeutic programs reduce stress-sensitive immunological parameter tumor necrosis factor alpha. Although existing data indisputably proves existence of comprehensive connections between tinnitus and psychological stress, there is still no empirical evidence to show whether stress as a etiological, or just contributing factor. Further research should give the ultimate answer on this subject.