A new study has found that inner ear impairment plays a major role in the increased risk of falling faced by Alzheimer’s patients.
The research, conducted at Johns Hopkins Medicine and published in the Journal of Alzheimer’s disease, found that patients with faulty vestibular systems — the sensory system within the ear that informs your brain about balance — had a risk of falling that was 50 per cent greater than Alzheimer’s patients with normal vestibular function. The study is believed to be the first to link the chances of these patients losing their balance with inner-ear issues.
The vestibular system is a ‘sixth hidden sense’
“We call the vestibular system the sixth hidden sense because it functions almost at a subconscious level,” said Yuri Agrawal, the study’s senior author and a professor of otolaryngology — head and neck surgery at the Johns Hopkins Medicine University School of Medicine. “It’s always ‘on’ and operates normally to keep us oriented as we move through space, sensing what’s up and what’s down and around us.”
When the system isn’t working properly, he added, “people experience vertigo — a disorienting, inability to navigate the world.”
Researchers decided to target the vestibular system because impairment to the canals and bony structures deep within the ear is a known cause of dizziness and vertigo in otherwise healthy individuals. “Falls are a major problem in people with Alzheimer’s disease, who fall at twice the rate compared with healthy older adults, and this often leads to injury, nursing home placement and early mortality,” Agrawal said.
To better understand the vestibular connection to the disease, researchers recruited 48 patients (27 female) with a mild or moderate Alzheimer’s diagnosis who were treated at Johns Hopkins Memory and Alzheimer’s Treatment Center and the Johns Hopkins Alzheimer’s disease Research Center between March 2018 and January 2020. Participants, who had a mean age of 65, were observed for a two-year period and subjected to devices that can track and mirror vestibular function.
Researchers found that participants who demonstrated impairment on these tests over time were 50 per cent more likely to fall than those with normal vestibular function. According to Agrawal, inner ear impairment results in an increased sway that leads to more falls.
With much of Alzheimer’s research currently focused on countering cognitive impairment, Agrawal suggested further study of the vestibular system as a way to improve the health and well-being of patients. “Vestibular impairment is treatable with balance exercises performed under the care of a physical therapist,” she said. “That could enhance the quality of life for both patients and caregivers.”
Alzheimer’s disease, the most common cause of dementia, is a degenerative condition that is believed to be the result of the accumulation of certain proteins in the brain that leads to the slow death of neurons. This process can eventually produce balance issues and symptoms of memory loss, difficulty thinking and changes in mood and behaviour.
There are over 500,000 Canadians living with dementia today, with another 25,000 diagnosed with the progressive disease every year, according to the Alzheimer Society. Two-thirds of those diagnosed over the age of 65 are women. At the rate at which the disease is growing, it currently costs over $10-billion a year to care for patients.
Dave Yasvinski is a writer with Healthing.ca