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Monday, February 4, 2019

New Study Links Hearing Loss with Greater Risk of Cognitive Decline

A new study links hearing loss with increased risk of subjective cognitive decline, adding more key evidence to the connection between these conditions.

Researchers from Brigham and Women's Hospital and Harvard Medical School analyzed data collected over eight years on 10,107 men aged 62 years and over who were asked about their hearing status and hearing aid use. They found that those who reported having hearing loss had a higher risk of cognitive decline—30 percent higher for men with mild hearing loss than those with normal hearing and 42 percent for those with moderate hearing loss. Among study participants with severe hearing loss, those who used hearing aids had 37 percent higher risk while those who didn't wear hearing aids had 54 percent higher risk of cognitive decline.

The participants received questionnaires about diseases and health-related topics like smoking, physical activity, and medications taken, explained lead author Sharon G. Curhan, MD. "We assessed subjective cognitive function (SCF) scores based on responses to a 6-item questionnaire administered in 2008, 2012, and 2016," she noted. "SCF decline was defined as a new report of at least one SCF concern during follow-up." Questionnaires on the participants' detailed dietary information were also administered in four-year intervals.

Considering the study's large sample size and prospective study design with long-term follow-up, it's a notable addition to current investigations into the connection between hearing loss and dementia.

"The challenges were considerable in conducting a longitudinal study of this scope, in an ongoing cohort of this large size, achieving such high rates of follow-up, using detailed validated measures to assess cognition and the many demographic, medical, dietary, and lifestyle factors that were considered as covariates in our multivariable analyses," Dr. Curhan noted. "We were also able to consider age, race, occupation, body mass index, waist circumference, smoking, physical activity, hypertension, diabetes, hypercholesterolemia, detailed dietary intake, aspirin, acetaminophen and NSAID use, and depression."

The researchers also looked at how hearing aid use affected the participant's trajectory of cognitive decline.  

"We found that among men with severe hearing loss, the size of the elevated risk of cognitive decline was somewhat smaller but was not statistically significantly different than the risk among men with severe hearing loss who used hearing aids," Dr. Curhan said. "However, we did not have detailed information on the many factors that can influence the effectiveness of hearing aid use." Thus, further investigations are needed to see if specific hearing-related management strategies could influence the risk of cognitive decline in this population.

"Another notable finding in our study is that in a sensitivity analysis that did not include questions potentially influenced by hearing status in the SCF score, the size of the relations was somewhat attenuated," Dr. Curhan told The Hearing Journal. "This suggests that some measures typically used in cognitive research could be sensitive to hearing ability. Therefore, hearing status could be an important methodologic consideration in studies of cognitive decline and dementia."