Causes of Dreaded Dementia : Prevention?

"Although the brain becomes smaller with age, the shrinkage seems to be fast-tracked in older adults with hearing loss, according to the results of a study by researchers from Johns Hopkins and the National Institute on Aging. The findings add to a growing list of health consequences associated with hearing loss, including increased risk of dementia, falls, hospitalizations, and diminished physical and mental health overall."

"For the study, Frank Lin, M.D., Ph.D., and his colleagues used information from the ongoing Baltimore Longitudinal Study of Aging to compare brain changes over time between adults with normal hearing and adults with impaired hearing. The Baltimore Longitudinal Study of Aging was started in 1958 by the National Institute on Aging to track various health factors in thousands of men and women."

"Previous research from other studies had linked hearing loss with marked differences in brain structure compared to those with normal hearing, both in humans and animals. In particular, structures that process information from sound tended to be smaller in size in people and animals with impaired hearing. Lin, an assistant professor at the Johns Hopkins University schools of medicine and public health, says it was unknown, however, whether these brain structural differences occurred before or after hearing loss."
Johns Hopkins Medicine ... January 22, 2014

Adults with hearing loss are significantly more likely than adults with normal hearing to develop dementia. — Istock

"The sharpness of an individual’s hearing has cascading consequences for various aspects of cognitive function. We’re only just beginning to understand how far-reaching these consequences are."
"Even if you have just a mild hearing loss that is not being treated, cognitive load increases significantly. You have to put in so much effort just to perceive and understand what is being said that you divert resources away from storing what you have heard into your memory."
Brandeis University Professor of Neuroscience, Dr. Arthur Wingfield

There seems to be general agreement in the highly specialized medical/scientific community that a link between hearing loss and dementia has been firmly established. That there are many potential causes of dementia, among which are depression, smoking, a sedentary lifestyle, social isolation, high blood pressure, lack of formal education as a child, and lastly peripheral hearing loss.

The prestigious medical journal Lancet had decided to strike a commission of several dozen experts in the field of cognition and risks of age-related cognitive decline. When the report was completed smoking and obesity were listed as major factors in the prevalence of dementia onset. Both smoking and obesity are well enough known as lifestyle predictors of a whole host of physical ills, not the least of which are cancer, heart disease, diabetes and stroke.

The commission authors studied the preventable risk factors potentially leading to dementia, then they estimated how much risk they believed to represent the intensification of each factor in establishing dementia. They settled on a global "population attributable fraction" by which to measure each of the possible underlying drivers toward dementia. As, for example, eliminating smoking would result in how much of a reduction in dementia?

Smoking, as it turned out, using the yardstick of the highest-to-lowest PAF on the established formula, ranked number three, while late-in-life depression (considered to be a preventable social issue) came in at number four. Further down the list of triggers to dementia came social isolation and physical inactivity, and so did high blood pressure. As for the second-placed trigger for mental decline, lack of secondary education fit that niche.

Lack of formal childhood education was placed in the "lifestyle factor" category, the risk given a 60 percent likelihood of potentially precipitating mental decline. Leaving school before attaining age eleven scored a high PAF, and it was ascertained through the calculations that 40 percent of the world population bears this risk factor. None however, ranked as high for the potential to move individuals into mental decline as peripheral hearing loss.

Studies have established the theory that people suffering peripheral hearing loss at or around age 55 double the ordinary individual's risk of dementia. Peripheral deafness is defined as hearing loss with no obvious central nervous system or brain causation, and as such the use of a hearing aid would alleviate the loss. Even so, the Lancet group concludes that it is unknown whether hearing aids have the capacity in their function to aid in halting cognitive decline.

So then, though midlife deafness may contribute to dementia as some neurologists posit, because the effort in attempting to interpret speech monopolizes "cognitive resources", it is still a theory. Theories abound, including one that loss of hearing leaves  the individual feeling sad which ages the individual more swiftly. Still others feel that hearing loss might possibly represent one of dementia's early symptoms.

There is obviously a long way to go in understanding the process, let alone establishing that some cases of dementia can be preventable.