Presbycusis phenotypes form a heterogeneous continuum when ordered by degree and configuration of hearing loss.
Many reports have documented age-by-frequency increases in average auditory thresholds in various human populations. Despite this, the prevalence of different patterns of hearing loss in presbycusis remains uncertain. We examined 'presbycusis phenotypes' in a database of 960 subjects (552 female, 408 male, 18-92 years) that each had 30 measures of peripheral hearing sensitivity: pure tone audiograms for left and right ears from 0.25 to 8 kHz and DPOAE for each ear with F(mean)=1-6.4 kHz. Surprisingly, the hearing phenotypes did not naturally separate into discrete classes of presbycusis. Principal component (PC) analysis revealed that two principal components account for 74% of the variance among the 30 measures of hearing. The two components represent the overall degree (PC1) and configuration of loss (Flat vs. Sloping; PC2) and the phenotypes form a continuum when plotted against them. A heuristic partitioning of this continuum produced classes of presbycusis that vary in their degree of Sloping or Flat hearing loss, suggesting that the previously reported sub-types of presbycusis arise from the categorical segregation of a continuous and heterogeneous distribution. Further, most phenotypes lie intermediate to the extremes of either Flat or Sloping loss, indicating that if audiometric configuration does predict presbycusis etiology, then a mixed origin is the most prevalent.
Department of Neurobiology and Anatomy, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Box 603, Rochester, NY 14642, USA. paul_allen@urmc.rochester.edu
Paul D
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Allen
David A
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Eddins
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D016000:Cluster Analysis; D019992:Databases as Topic; D005260:Female; D006309:Hearing; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011237:Predictive Value of Tests; D011304:Presbycusis / Q000145:classification* / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D025341:Principal Component Analysis; D012720:Severity of Illness Index; D012737:Sex Factors; D055815:Young Adult