When such efforts are made, Dr. Buchman added, his own clinical experience parallels that of Dr. Lin’s. “It’s very common for us to see older patients with hearing loss experience some general slowing of their cognitive decline when we treat them for their condition,” he said.
Explore this issue:May 2013
Richard K. Gurgel, MD, an assistant professor of surgery in the division of otolaryngology-head and neck surgery at the University of Utah Health Care in Salt Lake City, sides with Dr. Lin when it comes to appreciating the link between hearing loss and cognitive decline in older patients. He and his colleagues presented a study, funded in part by a grant from the NIH, demonstrating the strength of that link at the annual meeting of the American Otological Society (held in conjunction with the Combined Sections Meeting) in Orlando in April.
The prospective, case-controlled cohort study included 4,463 men and women aged 65 years or older who did not have dementia at baseline, as determined by clinical assessment and expert consensus. Of those patients, 700 had hearing loss, based on observation of hearing difficulties or the use of hearing aids. In the hearing loss group, Dr. Gurgel and his colleagues reported, 16.3 percent developed dementia over the course of the study, compared with 12.1 percent of those without hearing loss. Mean time to dementia was 10.3 years in the hearing loss group vs. 11.9 years for patients with normal hearing.
The researchers controlled for important variables, including gender, education and the presence of apolipoprotein E alleles, which have been shown in some studies to be associated with sensorineural hearing loss (Neurobiol Aging. 2012;33:2230.e7-2230.e12). Once those factors were accounted for, the investigators found that hearing loss was an independent predictor of the development of dementia. When they analyzed the rate at which those cognitive declines occurred, they found that scores on the Modified Mini-Mental State (3MS) examination declined at a rate of 0.26 more points per year in hearing loss patients than in those with normal hearing.
These findings “suggest that hearing impairment may be a marker for central, cognitive dysfunction in adults aged 65 years and older,” Dr. Gurgel and his coinvestigators reported. But he was quick to point out the limits of the study. “There’s a difference between correlation and causation,” he told ENTtoday. “We don’t yet know whether the observed findings are due to a true neurobiological causative effect of hearing loss on dementia or whether the two simply correlate due to other yet-to-be-determined factors.”