Two studies by researcher Dr. Frank Lin Johns Hopkins School of Medicine have found a relationship between hearing loss and dementia.
In a poignant article in the New York Times, author
Katherine Bouton describes her personal experiences with hearing loss and
studies that point to a link between hearing loss and dementia. “Cognitive
overload” is how she views the sensory challenge of straining to hear words to
the point that her brain seems to have no processing power left to search through the
storerooms of memory for a response.
The term is actually a variation on
a very real condition identified as “cognitive load” by Dr. Frank Lin, an otolaryngologist
and epidemiologist at Johns Hopkins School of Medicine. Dr. Lin has examined
the results of two studies— the Baltimore Longitudinal
Study of Aging and the Health ABC
Study—and found a relationship between hearing loss and dementia. Of the
639 subjects in the first study —who were between the ages of 60 and 80 and
were followed for 18 years—none had dementia at the beginning of the study.
Some did have hearing loss. Dr. Lin found that “Compared to individuals with
normal hearing, those individuals with a mild, moderate, and severe hearing
loss, respectively, had a 2-, 3- and 5-fold increased risk of developing
dementia over the course of the study.” The worse the hearing loss, the
greater the risk of developing dementia. The correlation remained true even
when age, diabetes and hypertension — other conditions associated with dementia
— were ruled out.
The second study reinforced the results of the first one,
but also found that those with hearing loss had a “30 to 40 percent faster rate
of loss of thinking and memory abilities” over a six-year period compared with
people with normal hearing. Again, the worse the hearing loss, the worse the
rate of cognitive decline was in the study.
These findings reinforce my own observation over many years
of treating patients with hearing loss. Dr. Lin speculates that possible
explanations include social isolation, which is often associated with hearing
loss and a known risk factor for dementia. Another possibility is the cognitive
load described above, and a third is some pathological process that causes both
hearing loss and dementia.
In the article, Ms. Bouton says common sense suggests that
if you don’t have to work so hard to hear, you have greater cognitive power to
listen and understand — and remember. And the sense of perceived isolation,
another risk for dementia, is reduced. My experience is that hearing aids can
assist in this process but they need to be programmed optimally for the user
and used consistently.
To read results of the latest study,
click here for the JAMA article: