Studies show unique factors in hearing loss across ethnicities
We all know hearing loss doesn’t discriminate. Affecting 48 million people in the U.S., hearing loss crosses the racial and cultural divide. Now, across the country, studies are being conducted comparing the rates of hearing loss in different races and ethnicities. These studies serve to highlight the roles factors such as biology and socioeconomics play in hearing loss.
In the largest study of hearing loss among Hispanic/Latino adults in the U.S., researchers looked at different subgroups of the Hispanic culture to determine whether there were differing degrees of hearing loss among them, and how the rate of hearing loss compared to the general population. 16,400 Latinos between the ages of 16 and 74 were exposed to different tones and pitches. The criteria for hearing loss used the World Health Organization’s definition for hearing loss, which is not being able to hear sounds at 25 decibels.
The study, done by the NIH/National Institute on Deafness and Other Communication Disorders, show that, on average, 15 percent of Hispanics in the United States have at least some degree of hearing loss, which is a rate comparable to the general population. However among the subgroups, researchers found that Puerto Ricans living in the United States have the greatest amount of hearing loss among the Latinos living in the U.S, at a rate of 21 percent (unilateral hearing loss). Chicanos, Hispanics of Mexican origin or descent, actually have the lowest incidence of unilateral hearing loss at 11 percent.
Researchers found the rate of hearing loss is strongly associated with socioeconomic factors, noise exposure and abnormal glucose metabolism. Diabetics and prediabetics, for example, had a much higher rate of hearing loss at 57 percent and 37 percent respectively. Even education plays a role; the study found those with high school diplomas were 30 percent less likely to have hearing loss. And people earning more than 75,000 a year were 42 percent less likely to have hearing loss than people earning less than $10,000 per year.
Other findings which are comparable to the general population concluded:
- Men were 66 percent more likely to have hearing loss;
- Adults age 65-74 years old were 18 times more likely to have hearing loss than younger adults age 18-44;
- Those exposed to loud noises were 30 percent more likely to have hearing loss.
According to James F. Battey, director of the NIH’s National Institute on Deafness and Other Communication Disorders (NIDCD), even mild deafness can hurt daily life interactions. “Hearing loss can affect a person’s overall quality of life, and has been linked to depression and dementia in older adults,” Battey said in a statement released by the NIH. “This study paints a detailed picture of hearing loss among a large and diverse group of Hispanic/Latino participants, and could help inform the development of intervention strategies to meet the needs of this growing population in the United States.”
"Now that we've identified some potential risk factors in Hispanics/Latinos, we need to follow up with long-term studies that determine if these modifiable factors predict the development of hearing impairment," said Karen J. Cruickshanks, Ph.D., lead author of the study and professor of population health sciences at the University of Wisconsin, Madison.
Another study, conducted at Johns Hopkins University, explored how biological factors come into play when it comes to hearing loss. The study was based on the demographic data from the National Health and Nutrition Examination Survey and used data collected over the past 40 years and combined with a current study of 717 participants. When looking at the rate of hearing loss in Caucasians as compared to African Americans, results showed that Caucasian participants were three times more likely than African Americans to experience hearing loss.
One important reason might be skin pigmentation. The researchers believe that melanin, produced by the cell pigments in the skin called melanocytes, plays a vital role. Though researchers note that further study is needed to completely confirm these results, it is suspected the melanin produced by the cells in the skin and inner ears of African-Americans might offer protection from the damage that can lead to hearing loss. And in an earlier study, noise-related hearing loss was examined and compared in both African American and Caucasian metal factory workers. The study concluded that that African Americans had a lower rate of hearing loss than their Caucasian colleagues.
Frank Lin, M.D., otologist at John Hopkins Hospital and lead researcher, thinks the findings could have a positive impact on future hearing loss treatments. “This finding could lead to pharmacological drugs that would be targeted to protect against hearing loss and specifically they would target the inner ear,” Dr. Lin said.