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Hearing loss expedited cognitive decline in seniors

Hearing loss appears to be associated with accelerated cognitive decline and risk for incident cognitive impairment in older adults, according to new research published in JAMA Internal Medicine.

“The prevalence of dementia is projected to double every 20 years because of the aging of the world population,” the researchers wrote. “Therefore, identifying factors and understanding mechanistic pathways that lead to cognitive decline and dementia in older adults represent a public health priority.”

Frank R. Lin, MD, PhD, of the department of otolaryngology at The Johns Hopkins School of Medicine, and colleagues studied 1,984 older adults (mean age, 77 years) who were enrolled in a larger prospective observational study that began in 1997-1998. At baseline, none of the study participants had prevalent cognitive impairment. Hearing tests were conducted at baseline and during year 5 of the study, and the adults were followed up for 6 years. Cognitive tests were performed during years 5, 8, 10 and 11.

A total of 1,162 older adults with baseline hearing loss had annual rates of decline in global and executive function that were 41% and 32% greater, respectively, than older adults with normal hearing. Older adults with baseline hearing loss were at a 24% greater risk for incident cognitive impairment (HR=1.24; 95% CI, 1.05-1.48) vs. those with normal hearing.

The severity of baseline hearing loss was also linearly associated with the rates of cognitive decline and the risk for incident cognitive impairment.

According to Lin and colleagues, there are several possible explanations for the association between hearing loss and cognitive decline, including poor verbal communication — which may confound cognitive testing — or a shared neuropathic origin between hearing and cognition. Hearing loss may also lead to social isolation and loneliness, which have been linked to cognitive decline in previous research.

However, the researchers said additional studies are necessary to better understand the relationship.

“Further research is needed to investigate what the mechanistic basis of this observed association is and whether such pathways would be amenable to hearing rehabilitative interventions,” they wrote.

Disclosure: Lin reports financial relationships with Pfizer and unpaid relationships with Cochlear Europe.