Past research has shown a link between hearing loss and steeper cognitive decline in old age, but few have tracked that relationship over a quarter century.
"With a large sample size and 25 years of follow-up of participants, this study clearly confirms that hearing loss is associated with cognitive decline in older adults," said the study's lead author, Helene Amieva. "Using hearing aids attenuates cognitive decline in elders presenting with hearing loss."
- The design behind the hearing aid, CBC Radio's The Current
- Hearing aid costs too high to bear alone, say seniors
Amieva, a researcher at the University of Bordeaux in France, pointed out that about 30 per cent of people age 65 and older have some degree of hearing loss and that's true of 70 per cent to 90 per cent of those aged 85 and older.
To see if hearing loss contributes to cognitive decline with age, and if hearing aids might offset that effect, the researchers used data from a large, long-term study of people in France who were 65 and older and living at home, rather than in institutional settings, when they were first recruited in 1989-1990.
Of this group, 137 people reported at the outset that they had major hearing loss, another 1,139 had moderate hearing problems such as trouble following conversations with several people talking or in a noisy background and 2,394 had no hearing troubles.
Cognitive decline was measured with a 30-point questionnaire often used to screen for dementia, which includes questions such as what year it is and asks individuals to repeat simple phrases. The participants' ability to perform activities of daily living well, and their degree of depressive symptoms were also assessed.
Overall, people with hearing loss scored lower for cognitive skills at the beginning of the study compared to the people without hearing loss.
"It is a significant decline, both from a clinical and statistical point of view," Amieva said.
"One thought is when individuals do have hearing loss, what happens is they miss bits and pieces of information and so it isolates them," said Thomas Zalewski of Bloomsburg University of Pennsylvania, who was not involved in the study. "So when people are isolated, they aren't communicating as much and what happens is this vicious cycle."
The study team concludes that auditory rehabilitation programs should be considered for older people who can't hear well. Such programs include listening and communication skills, as well as instruction in the use of hearing aids.