Cigarette Smoking Connected to Hearing Loss in Population-Based Study
We know that genetic, environmental, and lifestyle factors help determine an individual’s susceptibility to hearing loss in later age, but those factors may also play a role in the development of presbycusis, or age-related hearing loss. Cigarette smoking is a well-known risk factor for other chronic diseases, and it’s a lifestyle choice that may — through a combination of chemical effects on the human body — be a factor in hearing loss later in life.
The purpose of the study “Cigarette Smoking and Hearing Loss: The Epidemiology of Hearing Loss Study,” published in the Journal of the American Medical Association, was to evaluate the association between cigarette smoking and hearing loss in a large population of 3,753 adults aged 48 to 92 years. The average age of the participants was 65.8 years, and 57.7 percent were women. Cigarette-smoking status at the time of the baseline hearing examination in 1993 through 1995 was determined by self-report, and hearing loss was defined as a loss of at least 25 dB (a mild hearing loss) in the worse ear.
The results indicated that current smokers were 1.69 times as likely to have a hearing loss as nonsmokers, and that nonsmoking participants who lived with a smoker were more likely to have a hearing loss than those who were not exposed. In age-specific analyses, smoking history was associated with hearing loss in all but the oldest age group, and in each age group, the prevalence of hearing loss was higher among current smokers than nonsmokers.
The smoking and hearing loss relationship remained statistically significant in participants with both a history of occupational noise exposure and those without. Participants in the highest exposure category were 1.27 times as likely to have a hearing loss as those who were exposed to fewer than 10 packs of cigarettes per year. There was no significant interaction between gender and smoking. Overall, 45.9 percent of participants had a mild or greater hearing loss, 46 percent of participants were nonsmokers, 39.3 percent were ex-smokers, and 14.7 percent were current smokers.
These results are consistent with early clinical studies reporting worse hearing in smokers compared to nonsmokers, animal studies showing cochlear damage after exposure to cigarette smoke, and population-based self-reported data.
Studies involving animals have identified nicotinic-like receptors in the hair cells of the cochlea — the innerear organ responsible for sending hearing signals to the brain — which suggests that cigarette smoking may have direct ototoxic effects on hair cell function and an effect on the transmission of those hearing signals. These data, along with several other studies that have tied smoking to increased risk of hearing loss in humans, suggest that cigarette smoking may negatively affect hearing through ototoxic effects or by affecting oxygen in the blood that supplies the auditory system.