Less Hearing Loss in Future Generations?
Cruickshanks and Wichmann (2012) report hearing loss (like cardiovascular disease and perhaps dementia) may be on the decline as modifiable risk factors impact the eventual outcome. That is, hearing loss increases with age, but may be decreasing over time.
The authors note the Beaver Dam (Wisconsin) study included 3,753 people ages 48 to 94 years. For participants between ages 48 to 59 years, 21 percent had hearing impairment. For those over age 80 years, 90 percent had hearing impairment. After 10 years of follow-up, the cumulative incidence of hearing loss was 37 percent for those who entered the study with normal hearing (1,925 people). The adult off-spring of the original 3,753 people (above) included 3,285 people ages 21 to 84 years (evaluated between the years 2005 and 2008). Of those, 14 percent had hearing impairment. Specifically, for offspring between 21 and 34 years, 3 percent had hearing impairment and for those between 65 and 84 years, 43 percent had hearing impairment.
The authors report Zahn, Cruickshanks, Klein et al (2010) analyzed the (above) data and found the prevalence of hearing impairment declined by year of birth. Specifically, a male born in 1950 would have half the likelihood of acquiring hearing loss as a male born 20 years sooner (1930). The authors report two likely contributing factors to this trend (lesser hearing impairment in younger generations). The shift from blue to white collar jobs in the second half of the 20th century and, the implementation of occupational noise rules and regulations. Cruickshanks and Wichmann report epidemiologic studies based on cancer patients indicate rapid changes in disease occurrence rates tend to support environmental or behavioral changes impacting the result, as genetic changes occur quite slowly (perhaps hundreds or thousands of generations). Cruickshanks and Wichmann suspect more people in the 21st century will maintain good hearing into their later years, than cohorts from the 20th century.
For More Information, References, and Recommendations
Cruickshanks, KJ, Wichmann MA. (2012) Hearing Impairment and Other Health Conditions in Older Adults—Chance Associations or Opportunities for Prevention. Seminars in Hearing 33(3):217-224.
Zhan W, Cruickshanks KJ, Blein BEK et al. (2010) Modifiable Determinants of Hearing Impairment in Adults. Am J Epidemiol 171:260-266.