Study finds a common medical condition could put you at high risk for dementia

Photo: metacynic via Flickr

In a recent report published in the journal JAMA Neurology, it was revealed that dementia might actually be three times more deadly than official records imply.

In the wake of this news, it stands to reason that researchers are even more curious about the predictors that energize the elusive disease.

Impaired memory and cognitive decline often precede dementia diagnosis but sometimes the warning signs are more subtle.

According to a new study published in the journal, Neuron, hearing loss might not only increase one’s risk for developing dementia, but it also may help neurologists develop preventive measures.

“Epidemiological studies identify midlife hearing loss as an independent risk factor for dementia, estimated to account for 9% of cases. We evaluate candidate brain bases for this relationship. These bases include a common pathology affecting the ascending auditory pathway and multimodal cortex, depletion of cognitive reserve due to an impoverished listening environment, and the occupation of cognitive resources when listening in difficult conditions,” the authors wrote in the report.  In particular, we consider how aberrant activity in the service of auditory pattern analysis, working memory, and object processing may interact with dementia pathology in people with hearing loss. “

The research team is based out of Newcastle University, in the United Kingdom.

Hearing loss has been shown to be linked to dementia in previously conducted epidemiological studies:  These indicate that a tenth of the 47 million dementia diagnoses that occur worldwide are closely associated with hearing loss. Even still there has been no direct literature on this correlation hitherto

“We highlight how the effect of hearing interventions on dementia depends on the specific mechanism and suggest avenues for work at the molecular, neuronal, and systems levels to pin this down,” the authors continued.

The potential mechanisms were as follows:  a lack of sound-related input that induces t brain shrinking; and cognitive impairment that causes people to assess other brain resources to compensate for their hearing loss.

The temporal lobe is one of the four major lobes located in the cerebral cortex. and it is ear level within the skull.

On balance, the temporal lobe is most often associated with conscious and long-term memory but the researchers were interested in its function with respect to auditory storage and processing.

A meta-analysis of 36 cross-sectional studies (each measuring cognitive function and pure tone audiometry) yielded a significant association between hearing loss and both cognitive impairment and dementia.

When risk factors like sex, age, race, and smoking weed controlled for,  a stratified risk as a function of hearing loss, 41 of 79 (51%) incident cases were successfully linked to nonvascular dementia and 38 incident cases were vascular.

Although the data is limited thus far, this is a huge breakthrough that warrants more literature.

“This will require extensive further work and debate involving epidemiologists, clinicians treating hearing loss, clinicians treating dementia, and basic scientists,” the authors concluded. “We hope that precise definition of the possible mechanisms will lead to helpful further testing by basic scientists working at the molecular, neuronal, and systems levels.”