Does tinnitus distress depend on age of onset?
From: PLoS One. 2011;6(11):e27379
Tinnitus is the perception of sound in the absence of an auditory stimulus. Averaged over all age groups 5–15% of the western population experience some form of tinnitus. Many people can cope with chronic tinnitus, but about 1–2% of the population experience significant impairments in their quality of life due to their tinnitus.
The prevalence of chronic tinnitus increases with increasing age, peaking at 14.3% in people between 60 and 69 years of age. The increase in tinnitus prevalence with age is at least partly explained by the fact that hearing loss is an important risk factor for tinnitus and hearing loss prevalence also increases with age.
Neuroplastic processes play a crucial role both in the generation of tinnitus and in the amount of suffering. Imaging studies reveal that neuroplastic changes in the central auditory system are generating the tinnitus percept and that coactivation of nonauditory structures in the frontal cortex and the limbic system are involved in tinnitus related distress.
Studies in animals and humans have shown that the mechanisms of cortical plasticity change over the lifetime with a tendency of decreased and less efficient neuroplastic potential as demonstrated by decreased induction and maintenance of long-term-potentiation and reduced long-term depression-like effects with advancing age.
With these changes in the neuroplastic potential across the life span, age may not only have an influence on the incidence of tinnitus, but also on tinnitus related distress. A first hint for such a relation is given by a large epidemiological study demonstrating that people with bothersome tinnitus are elder than those with non-bothersome tinnitus. Considering that tinnitus duration also influences its annoyance the authors focused here especially on the role of tinnitus onset. In detail the authors hypothesized that the age of tinnitus onset may influence the perceived tinnitus related distress. More specifically, they assumed that early tinnitus onset is associated with less distress than later tinnitus onset.
The main finding of this analysis is an influence of the age at tinnitus onset on tinnitus related distress. Higher age at tinnitus onset is associated with higher tinnitus related distress. To the authors knowledge this is the first report about an influence of age of tinnitus onset on tinnitus severity. This effect is independent from the age at tinnitus assessment, the duration of tinnitus and the type of tinnitus onset (gradual versus abrupt).
A large variety of different variables have been identified in the past as contributing factors to tinnitus distress, among them tinnitus loudness, hearing loss, vertigo/dizziness, hyperacusis, depression, anxiety and personality factors. This study adds “age of onset” as an additional influencing factor underscoring the relevance of time related aspects in the pathophysiology of tinnitus. Earlier studies identified age and tinnitus duration as relevant factors. Age is strongly influencing tinnitus prevalence and tinnitus duration plays an important role for response to treatment. Though the effect of age of onset is statistically highly significant, it is rather small. However, considering the many variables, which exert a known influence on tinnitus related distress, this is not surprising.
Even though we cannot derive direct implications of the results on the clinical management of tinnitus patients, they may be relevant for a better understanding of both physiologic changes of brain function with increasing age and the pathophysiologic mechanisms involved in the generation of tinnitus distress. Many aspects of brain structure, brain function and brain plasticity are changing with age in a complex way. These changes also involve adaptive and compensatory neural mechanisms. Both the generation of tinnitus and the amount of tinnitus distress are thought to depend on adaptive and compensatory brain mechanisms. In this context higher tinnitus distress at higher age of onset suggests an age-related decline in the efficiency of this compensatory mechanism for tinnitus. Thus the finding is in line with the observation that a decrease of cognition is related to higher tinnitus related distress. Future studies are invited to further characterize the interactions between age related changes in neuroplastic potential, cognitive function and their influence on tinnitus distress.
Tinnitus related distress is influenced by many variables such as tinnitus loudness, hearing loss, vertigo/dizziness, hyperacusis, depression, anxiety and personality factors. Here the authors suggest that the age at tinnitus onset might be an additional factor. Patients with a later onset of tinnitus in their life report greater distress than patients with an early tinnitus onset. The decline of neuroplasticity with advancing age might be an underlying mechanism for this observation.