Literature Review

Impaired senses, especially smell, linked to dementia


“Sheds further light”

Commenting on the study, Jo V. Rushworth, PhD, associate professor and national teaching fellow, De Montfort University Leicester (England), said it “sheds further light on the emerging links” between multisensory impairment and cognitive decline leading to dementia. “The authors show that people with even mild loss of function in various senses are more likely to develop cognitive impairment.”

Dr. Rushworth was not involved with the study but has done research in the area.

The current results suggest that measuring patients’ hearing, vision, sense of smell, and touch might “flag at-risk groups” who could be targeted for dementia prevention strategies, Dr. Rushworth noted. Such tests are noninvasive and potentially less distressing than other methods of diagnosing dementia. “Importantly, the relatively low cost and simplicity of sensory tests offer the potential for more frequent testing and the use of these methods in areas of the world where medical facilities and resources are limited.”

This new study raises the question of whether the observed sensory impairments are a cause or an effect of dementia, Dr. Rushworth noted. “As the authors suggest, decreased sensory function can lead to a decrease in social engagement, mobility, and other factors which would usually contribute to counteracting cognitive decline.”

The study raises other questions, too, said Dr. Rushworth. She noted that the participants who experienced more severe sensory impairments were, on average, 2 years older than those with the least impairments. “To what degree were the observed sensory deficits linked to normal aging rather than dementia?”

As well, Dr. Rushworth pointed out that the molecular mechanisms that “kick-start” dementia are believed to occur in midlife – so possibly at an age younger than the study participants. “Do younger people of a ‘predementia’ age range display multisensory impairments?”

Because study participants could wear glasses during vision tests but were not allowed to wear hearing aids for the hearing tests, further standardization of sensory impairment is required, Dr. Rushworth said.

“Future studies will be essential in determining the value of clinical measurement of multisensory impairment as a possible dementia indicator and prevention strategy,” she concluded.

The study was funded by the National Institute on Aging, the National Institute of Nursing Research, and the Alzheimer’s Association. Dr. Brenowitz and Dr. Rushworth have reported no relevant financial relationships.

A version of this article originally appeared on


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