Obese adolescents are more likely than their normal-weight peers to suffer hearing loss, scientists, including one of Indian-origin, have claimed.
US researchers found that obese teenagers suffered increased hearing loss across all frequencies and were almost twice as likely to have unilateral (one-sided) low-frequency hearing loss than their counterparts.
"This is the first paper to show that obesity is associated with hearing loss in adolescents," said study first author Anil K Lalwani, professor and vice chair for research, Department of Otolaryngology/Head & Neck Surgery, Columbia University Medical Center.
The study found that obesity in adolescents is associated with sensorineural hearing loss across all frequencies (the frequency range that can be heard by humans); sensorineural hearing loss is caused by damage to the inner-ear hair cells.
The highest rates were for low-frequency hearing loss 15.16 per cent of obese adolescents compared with 7.89 per cent of non-obese adolescents.
People with low-frequency hearing loss cannot hear sounds in frequencies 2,000 Hz and below; they may still hear sounds in the higher frequencies (normal hearing range is from 20 Hz to 20,000 Hz).
Often they can still understand human speech well, but may have difficulty hearing in groups or in noisy places.
Although the overall hearing loss among obese adolescents was relatively mild, the almost two-fold increase in the odds of unilateral low-frequency hearing loss is particularly worrisome, the study said.
The study analysed data from nearly 1,500 adolescents from the National Health and Nutrition Examination Survey – a large, nationally representative sample of adolescents between the ages of 12 and 19, conducted from 2005 to 2006 by the National Center for Health Statistics of the Centers for Disease Control and Prevention.
Participants were interviewed at home, taking into account family medical history, current medical conditions, medication use, household smokers, socioeconomic and demographic factors, and noise-exposure history.
Lalwani and his colleagues speculate that obesity may directly or indirectly lead to hearing loss. Although additional research is needed to determine the mechanisms involved, they theorise that obesity-induced inflammation may contribute to hearing loss.
The study was published in The Laryngoscope, a journal published by the American Laryngological, Rhinological and Otological Society.