April Flowers for redOrbit.com – Your Universe Online
A new study led by researchers at Columbia University Medical Center shows obese adolescents are more likely to have hearing loss problems than their normal-weight peers. The study findings, published in The Laryngoscope, demonstrated that obese adolescents have increased hearing loss across all frequencies and were almost twice as likely to have unilateral (one-sided) low-frequency hearing loss.
“This is the first paper to show that obesity is associated with hearing loss in adolescents,” said Anil K. Lalwani, professor and vice chair for research, Department of Otolaryngology/Head & Neck Surgery, Columbia University Medical Center.
Obesity in adolescents is associated with sensorineural hearing loss — caused by damage to the inner-ear hair cells — across all frequencies in the range that can be heard by humans, according to the study. The highest rates of hearing loss were for low-frequencies — over 15 percent of obese adolescents compared with almost 8 percent of non-obese adolescents. Low-frequency hearing loss sufferers cannot hear sounds in frequencies 2,000 Hz and below, although they may still hear sounds in the higher frequencies. Normal human hearing range is from 20 Hz to 20,000 Hz. Such sufferers can often still understand human speech, but may have difficulty hearing in groups or in noisy places.
“These results have several important public health implications,” said Dr. Lalwani, who is also an otolaryngologist at New York Presbyterian Hospital/Columbia University Medical Center. “Because previous research found that 80 percent of adolescents with hearing loss were unaware of having hearing difficulty, adolescents with obesity should receive regular hearing screening so they can be treated appropriately to avoid cognitive and behavioral issues.”
In general, overall hearing loss among obese adolescents is relatively mild, the study found, although the nearly two-fold increase in the odds of unilateral low-frequency hearing loss is particularly worrisome. The findings suggest early, and possibly ongoing, injury to the inner ear that could progress as the adolescents become obese adults. The researchers say more research is needed on the adverse effects of this early hearing loss on social development, academic performance and behavioral and cognitive function.
“Furthermore, hearing loss should be added to the growing list of the negative health consequences of obesity that affect both children and adults — adding to the impetus to reduce obesity among people of all ages,” said Dr. Lalwani.
Nearly 17 percent of children in the US are obese, which is defined as having a body mass index (BMI) of 95 percentile. Unlike adult BMI, which is expressed as a number based on weight and height, BMI in children is expressed as a percentile. Previous research has identified obesity and its associated morbidities have been identified as a risk factor for hearing loss in adults.
The research team analyzed data from almost 1,500 individuals who participated in the National Health and Nutrition Examination Survey. Conducted from 2005 to 2006 by the National Center for Health Statistics of the Centers for Disease Control and Prevention (CDC), the survey was a large, nationally representative sample of adolescents between the ages of 12 and 19.“¯Participating adolescents were interviewed in their homes, taking into account family medical history, current medical conditions, medication use, household smokers, socioeconomic and demographic factors, and noise-exposure history.
The research team suggests obesity may directly or indirectly lead to hearing loss. More research is necessary to determine the mechanisms involved; however, the team theorizes that obesity-induced inflammation may contribute to hearing loss.“¯Obese children have been found to have low levels of the anti-inflammatory protein adiponectin, which is secreted from adipose tissue. In obese adults, low levels have been associated with high-frequency hearing loss, which affects a person’s ability to understand speech. Secondary diseases often associated with obesity — which include type 2 diabetes, cardiovascular disease and high cholesterol — have all been reported to be associated with loss of peripheral hearing (relating to the outer, middle, and inner ear) and could also contribute indirectly to hearing loss.