Hearing Loss and Dementia

Exploring the link between hearing loss and increased risk of dementia.

According to the World Health Organization (WHO), there are 35.6 million people with dementia and there are 7.7 million new cases every year worldwide. Dementia is one of the major causes of disability and dependency among older people and has physical, psychological, social and economic impact on caregivers, families and society.

About 360 million people worldwide have disabling hearing loss (loss greater than 40dB in the better hearing ear in adults and a hearing loss greater than 30dB in the better hearing ear in children).

A study by Lin et al, published in Archives of Neurology, looked at the link between hearing loss and dementia. For the study, Frank Lin, M.D., Ph.D., and his colleagues used information from the ongoing Baltimore Longitudinal Study of Aging to compare brain changes over time between adults with normal hearing and adults with impaired hearing. The Baltimore Longitudinal Study of Aging was started in 1958 by the National Institute on Aging to track various health factors in thousands of men and women. Participants whose hearing was already impaired at the start of the sub-study had accelerated rates of brain atrophy compared to those with normal hearing. Those with impaired hearing also had significantly more shrinkage in particular regions, including the superior, middle and inferior temporal gyri, brain structures responsible for processing sound and speech.

The Link

  1. People with hearing loss tend to isolate themselves and isolation is a risk factor for dementia whether you’re hearing or hearing-impaired.
  1. Hearing loss stresses cognitive load. When you aren’t hearing very well, a lot of effort goes towards straining to hear what the other person said. So much effort is spent on decoding the information that it is very hard to absorb the information.  The study author, Lin, theorized: “When the clarity of words is garbled, the brain has to reallocate resources to hear at the expense of other brain functions.”
  1. The third possible explanation is the one that is most alarming and it’s the one that scientists like Dr. Lin and others are beginning to look at, and that’s that there’s an underlying pathological mechanism that has an influence on both hearing loss and dementia. It could be something environmental. It could be something genetic. They just don’t know. Although the brain becomes smaller with age, the shrinkage seems to be fast-tracked in older adults with hearing loss, according to the results of a study by researchers from Johns Hopkins and the National Institute on Aging. The findings add to a growing list of health consequences associated with hearing loss, including increased risk of dementia, falls, hospitalizations, and diminished physical and mental health overall.

The study also gives some urgency to treating hearing loss rather than ignoring it. "If you want to address hearing loss well," Lin says, "you want to do it sooner rather than later. If hearing loss is potentially contributing to these differences we're seeing on MRI, you want to treat it before these brain structural changes take place."

Treating existing hearing loss should now be added to the list of things people can do to help prevent dementia. Other items on the list include keeping your mind active, exercise, maintaining a healthy blood pressure, and eating a healthy diet.


Belluck, Pam (2/11/2013). Could Hearing Loss and Dementia Be Connected? The New York Times. Accessed 01/27/2015 from http://www.nytimes.com/2013/02/12/science/could-hearing-loss-and-dementia-be-connected.html?pagewanted=1&_r=0 

Hearing Loss Linked to Accelerated Brain Tissue Loss (1/22/2014). Johns Hopkins Medicine. Accessed 1/27/2015 from http://www.hopkinsmedicine.org/news/media/releases/hearing_loss_linked_to_accelerated_brain_tissue_loss 

Lin FR, Metter EJ, O’Brien RJ, Resnick SM, Zonderman AB, Ferrucci L. Hearing loss and incident dementia. Arch Neurol. 2011;68(2):214-220. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3277836/#__ffn_sectitle - See more at http://www.hearingreview.com/2014/01/update-on-dementia-and-hearing-loss/#sthash.BtZMy9Ac.dpuf 

Hampton, D. Update on dementia and hearing loss. Hearing Review. 2014, January: 42 - See more at http://www.hearingreview.com/2014/01/update-on-dementia-and-hearing-loss/#sthash.BtZMy9Ac.dpuf 

Mayo Clinic Staff (n.d.) Dementia Prevention. Mayo Clinic. Accessed 1/27/2015. 

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