Multiple recent studies have shown that having a hearing loss can increase the likelihood of cognitive problems and dementia. In 2013 Frank Lin, M.D., Ph.D., an otologist and epidemiologist at Johns Hopkins University, and his fellow researchers followed the overall cognitive abilities of roughly 2000 individuals with an average age of 77 over the course of six years. In just that short timeframe, the adults who began the program with a hearing impairment significant enough to interfere with conversations demonstrated a 24 percent higher probability of having their cognitive function diminish. Therefore, the researchers concluded that the presence of the hearing loss accelerated the age-related cognitive decline. In this blog, we will discuss this correlation between hearing loss and dementia.
In a much longer previous study in 2011 that focused on dementia specifically, Dr. Lin and his colleagues tracked the cognitive health of over 600 people who began the study with sharp mental ability for 12 to 18 years. The results were surprising. What they discovered was that the higher the degree of hearing loss, the greater the risk the individual would develop dementia.
More Studies on Hearing Loss and Dementia
More recently, Dr. Lin, reported in the journal Neuroimage that people with hearing loss had accelerated rates of brain atrophy when compared with those who have normal hearing. Furthermore, the scientists found that subjects with hearing impairment lost one cubic centimeter more of brain tissue per year than their normal hearing counterparts. They also had more shrinkage in the areas of the brain responsible for processing sound and speech. While startling, the results were not completely surprising since portions of the brain tend to atrophy, similar to muscles, without stimulation. If the ear cannot detect sounds, then no signal will be transmitted to stimulate the brain’s auditory cortex leading to atrophy and shrinkage of the brain. Dr. Arthur Wingfield, Brandeis University Professor of Neuroscience, found similar results when using MRI to examine hearing loss and its effects on the brain. In addition he said, “Even if you have just a mild hearing loss that is not being treated, cognitive load increases significantly.”
Now research is focusing on how to prevent and reverse hearing loss and dementia. It seems there is consensus that the key is detecting hearing loss early and addressing it right away. The longer people wait, and the more severe the hearing loss becomes, the more detrimental the cognitive effects, up to and including dementia. Preliminary research is showing that the use of amplification may even have the result of being able to reverse some cognitive decline and dementia, but further study must be completed to determine the extent to which dementia might be able to be reversed with hearing aids. However, it makes sense that it is easier to prevent troubles rather than reverse them. As Dr. Lin put it, “If you want to address hearing loss well, you want to do it sooner rather than later. If hearing loss is potentially contributing to these differences we’re seeing on MRI, you want to treat it before these brain structural changes take place.” So treat it rather than ignore it.