Dogma and belief: the primary lesion in age-related hearing loss is old news

Presbycusis, or age-related hearing loss, is the most common sensory deficit globally, and the biggest modifiable risk factor for a later dementia diagnosis. Despite its ubiquity, however, the primary pathology contributing to presbycusis is reportedly contentious, particularly the relative role of damage to the sensory outer hair cells compared to the stria vascularis, an important inner ear structure that maintains the ionic concentration of inner ear fluids that surround it. To determine what might be the "dogma" of the field regarding the primary pathology in presbycusis, we conducted an online Google survey (https://forms.gle/GPreoePmRxBBkchc7) asking relevant respondents in the field their opinions on the matter. In Question (Q1), respondents were asked to rate in your opinion from least likely to most likely (on a scale 1 to 4 [being most likely]) what is the primary pathology contributing to presbycusis? in terms of damage to: i) the inner hair cells, ii) outer hair cells (OHCs), iii) spiral ganglion, iv) stria vascularis. The term dogma suggests that the proportion of people in the field who believe that the main cause of presbycusis is damage to the stria vascularis is at least 50%. The results of our survey estimated this proportion to be 19/101 = 0.188 (95% CI [0.124 0.275]) and a two-sided test of the null hypothesis that this proportion is at least 0.5 was rejected (p < 10-10). When it came to opining what other professionals in the field consider to be the primary pathology contributing to presbycusis (Q2), the tendency to rank damage to OHCs as being the primary pathology was 45%. Stria vascularis was least likely to be ranked 4 (11%) by professionals in the field opining about the beliefs of others. Even when noise damage was excluded as a factor (Q3), the most likely contributing factor to presbycusis was stated to be damage to the OHCs (42%). Our data suggest the dogma of the field is that damage to outer hair cells is the primary pathology in presbycusis.