How Are Hearing Loss and Dementia related?
It (hearing loss) not only increases age-related memory loss, it increases the incidents of Alzheimer’s disease so if you can prevent the onset of Alzheimer’s disease or delay it with good hearing devices that’s a major public health advance.
Quote by Erik Kandel, Recipient of the Nobel Prize in Physiology or Medicine
Hearing Loss impacts over 48 Million people in the U.S. and is listed by the Department of Health and Human Services as the 3rd most common chronic disorder affecting today’s seniors. Unfortunately, for most of us, age-related hearing loss is inevitable; impacting nearly 50% of seniors between the ages of 60-70, almost 2/3rd of people between the age of 70-80, and nearly 80% of individuals over the age of 80. Age-related hearing loss is characterized by the progressive loss of receptor (hair) cells in the ear, that consequently reduces the quantity, and quality, of neural connections from the ear to the brain. This slow-onset disease can have a significant impact on several key brain areas, including the memory, hearing, speech and language portions of cognition. Several key research studies have pointed to the potential links of hearing loss and Dementia, including the groundbreaking work from Dr. Lin and his colleagues at Johns Hopkins Medical Center that indicate hearing loss can increase the risk of Dementia by 200-500% (see summary data in Figure 1).
Every 3-4 seconds another patient is diagnosed with Dementia. Rates of Dementia are estimated to triple in the next 30 years. Unlike some other diseases, with Dementia the physical body is estimated to outlive the individual’s mental capabilities by 10 or more years. There is no cure for this catastrophic disease, but there are treatments available, including several ways to decrease your risk of developing Dementia.
Recent research has found that hearing loss can increase the risk of developing Dementia by 200-500%. This report, from researchers at Johns Hopkins Medical Center and the National Institute on Aging found that individuals with hearing loss (when compared to participants with normal hearing) are at a significantly higher risk of developing Dementia over time. The more hearing loss they had, the higher their likelihood of developing the memory-robbing disease. “A lot of people ignore hearing loss because it’s such a slow and insidious process as we age,” Dr. Frank Lin (of Johns Hopkins Medical Center) says. “Even if people feel as if they are not affected, we’re showing that it may well be a more serious problem.”
Three risk factors associated with hearing loss and Dementia include Social Isolation, Cerebral Atrophy and Cognitive Overload.
- Hearing Loss and Social Isolation
Withdrawal from social situations is common in individuals with hearing loss. Many studies cite feelings of embarrassment, fear of making mistakes in conversations, and feeling like you are not part of the conversation as the common rational for individuals with hearing impairment to separate themselves from family, friends and community. This retreat from social activity has even been found in individuals with a mild degree of hearing loss. In addition, individuals with hearing loss are less likely to engage in physical activity. Both increased social isolation and reduced physical activity are strong risk factors for the development of Dementia.
- Hearing Loss and Cerebral Atrophy (brain shrinkage)
The association of a shrinking brain, resulting from the loss of neurons, with Dementia has been long documented. Even people with MCI (Mild Cognitive Impairment) show signs of significant cerebral atrophy. In recent years, scientific studies using advanced brain imaging techniques (including fMRI – Functional Magnetic Resonance Imaging) have demonstrated that hearing impairment is associated with accelerated brain atrophy in both the overall brain, as well as even more advanced reductions in volume associated with the memory, hearing, speech and language portions of the brain.
- Hearing Loss and Cognitive Overload
Hearing loss is not normal, and neither is the excess strain that is puts on your brain. While hearing loss may be more common as we age, it is critical that hearing loss be treated. With hearing loss, the brain is constantly on ‘overload’ trying to fill in the missing pieces, and follow the conversation. Increased cognitive load is considered a risk factor for developing Dementia. Cognitive load, as measured by pupillometry, is a measurement of how hard your brain is working to follow a conversation. Recent research has found that individuals who treat their hearing loss do not work as hard to listen (i.e. have a reduced cognitive load) and have as much as a 20% increase in memory recall when following a conversation.