Hearing impairment in older adults may indicate increased risk of faster cognitive decline with age, a study claims. Researchers from University of California San Diego in the US tracked 1,164 participants for up to 24 years.
All had undergone assessments for hearing acuity and cognitive function between the years 1992 to 1996 and had up to five subsequent cognitive assessments at approximately four-year intervals. None used a hearing aid.
The study, published in the Journal of Gerontology: Series A Medical Sciences, found that almost half of the participants had mild hearing impairment, with 16.8 per cent suffering moderate-to-severe hearing loss.
Those with more serious hearing impairment showed worse performance at the initial visit on a pair of commonly used cognitive assessment tests. Hearing impairment was associated with greater decline in performance on these tests over time, both for those with mild hearing impairment and those with more severe hearing impairment.
However, the association of mild hearing impairment with rate of cognitive decline was modified by education. Mild hearing impairment was associated with steeper decline among study participants without a college education, but not among those with higher education. Moderate-to-severe hearing impairment was associated with steeper MMSE decline regardless of education level.
"We surmise that higher education may provide sufficient cognitive reserve to counter the effects of mild hearing loss, but not enough to overcome effects of more severe hearing impairment," said Linda K McEvoy, a professor at University of California, San Diego.
Degree of social engagement did not affect the association of hearing impairment with cognitive decline. The findings show the need for physicians to be aware that older patients with hearing impairments are at greater risk for cognitive decline.
Researchers also emphasised the importance of preventing hearing loss at all ages, since hearing impairment is rarely reversible. One important way to protect hearing, they said, is to minimise loud noise exposure since this is the largest modifiable risk factor for hearing impairment.