Multiple studies have shown a connection between loss of sensory functions such as vision and hearing with a loss of cognitive abilities, Jane E. Brody writes for The New York Times.
This potential connection matters in particular because the number of adults struggling with poor vision is expected to double by 2050; two-thirds of adults older than 70 deal with hearing loss; and instances of dementia are doubling every 20 years.
One study published in JAMA Ophthalmology examined 33,000 participants and found an association between poor vision and poor cognition. “While this association doesn’t prove vision loss causes cognitive decline, intuitively it makes sense that the less engaged people are with the world, the less cognitive stimulation they receive, and the more likely their cognitive function will decline,” said lead author Dr. Suzann Pershing, ophthalmologist at Stanford University School of Medicine.
Other evidence suggests that hearing loss can more swiftly bring about cognitive decline, though researchers are unsure whether wearing good hearing aids can reduce dementia risk or delay onset, Brody writes.
Dr. Frank R. Lin, otolaryngologist at the Johns Hopkins Center on Aging and Health, discussed three possible reasons bad hearing and dementia are connected. One, the brain has to work harder to interpret the garbled sounds it receives. Two, the inability to hear properly sometimes socially isolates people. Three, hearing loss causes more brain atrophy in the hearing portion of the brain; this portion also helps with memory, learning and thinking.
People 40 to 54—even with no symptoms of or risk factors for vision loss—should have a full eye exam every two to four years, and people 55-64 should have one every year, according to the American Academy of Ophthalmology, Brody reports. Everyone should get a hearing test at least every 10 years, and those over 50 should get one every three years, the American Speech-Language-Hearing Association recommends.