The Risk of Hearing Loss for Dementia
A new meta-analysis published by the Lancet Commission focused on the rising rates of dementia globally. Currently, an estimated 47 million people worldwide suffer from dementia, with that number expected to triple by 2050. The global cost of dementia in 2015 was estimated to $818 billion, with nearly 85 percent of that total attributed to family and social costs, rather than medical care.
One of the main goals of the article was to consolidate the huge progress made regarding prevention and management of dementia. Specifically, the commission considered modifiable risk factors for dementia, based on estimating the population attributable fraction (PAF), which is the percentage reduction in new cases over a given time if a particular risk factor was completely eliminated. To date, the modifiable risk factors have focused on cardiovascular risk factors for dementia (e.g., diabetes, hypertension), plus obesity, physical inactivity, smoking, depression, and low childhood educational attainment.
For the first time, however, hearing loss was included as a preventable risk factor for PAF calculation, based on recent peer-reviewed studies that have appeared in the literature. The risk of hearing loss for dementia in a meta-analysis of three studies was conducted; the commission stated clearly that the mechanism underlying cognitive decline associated with peripheral hearing loss is not yet clear, as well as whether the use of hearing aids may prevent or delay the onset of dementia. Notably, however, they stated that hearing loss might add to the "cognitive load" of a vulnerable brain, lead to social isolation or depression or brain atrophy, all of which COULD contribute to the accelerated cognitive decline.
Analysis reported in the study suggested that the risk of hearing loss for dementia in the meta-analysis was higher than the risks from other individual risk factors listed above, but was also of concern because the age-related prevalence of hearing loss was higher than for the other risk factors, affecting nearly one-third of those over 55 years of age. This resulted in a weighted PAF of 9.1 percent for hearing loss—higher than ANY other single risk factor, including hypertension, childhood education, or smoking.
This study has important societal implications—for the first time, hearing loss is being identified as a modifiable risk factor for one of the most significant age-related global health conditions, and this is certain to continue to raise awareness for the importance of healthy hearing in the aging population.
Livingston G, Sommerlad A, Orgeta V, Costafreda SG, Huntley J, Ames D, Ballard C, Banerjee S, Burns A, Cohen-Mansfield J, Cooper C, Fox N, Gitlin LN, Howard R, Kales HC, Larson EB, Ritchie K, Rockwood K, Sampson EL, Samus Q, Schneider LS, Selbæk G, Teri L, Mukadam M. (2017) Dementia prevention, intervention, and care. The Lancent Commissions July 20. www.thelancet.com.