Hearing loss is independently associated with faster cognitive decline and more incidence of cognitive impairment in older adults, a study found, and the rates of declines were associated with the severity of the loss.
Researchers conducted a prospective observational study among nearly 2,000 older adults (mean age, 77.4 years) without cognitive impairment (Modified Mini-Mental State Examination [3MS] score, 80 or more). Hearing was defined at baseline and cognitive testing by the 3MS and the Digit Symbol Substitution test were done over a period of 11 years. Cognitive impairment was defined as a 3MS score of less than 80 or a decline of more than 5 points.
Results appeared Jan. 21 at JAMA Internal Medicine.
The nearly 1,200 people who lost hearing had annual rates of decline in 3MS and Digit Symbol Substitution test scores that were 41% and 32% greater, respectively, than those among individuals with normal hearing.
Compared to those with normal hearing, individuals with hearing loss at baseline had a 24% (hazard ratio, 1.24; 95% CI, 1.05-1.48) increased risk for cognitive impairment. Rates of cognitive decline and the risk for incident cognitive impairment were linearly associated with the severity of an individual's baseline hearing loss.
Researchers noted that those who lost some hearing would require 7.7 years to decline by five points on the 3MS compared with 10.9 years in individuals with normal hearing.
"Our results demonstrate that hearing loss is independently associated with accelerated cognitive decline and incident cognitive impairment in community-dwelling older adults," the authors comment. "The magnitude of these associations is clinically significant, with individuals having hearing loss demonstrating a 30% to 40% accelerated rate of cognitive decline and a 24% increased risk for incident cognitive impairment during a six-year period compared with individuals having normal hearing."