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New tool uses audio, visual stimuli to help detect cognitive decline
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Responses to audio and video stimuli were effective as a cognitive impairment screening tool, according to findings recently published in Scientific Reports.
“Age-related changes characteristically have a negative impact on sensory, perceptual, emotional and higher-order, memory-related and executive functions. Yet, healthy older adults typically show an enhancement in the gain resulting from multisensory integration of redundant cross-sensory, but not unisensory, information compared to younger adults. [Multisensory integration] is known to provide a wide range of benefits across both behavior and neural processing,” Micah M. Murray, a professor at the Laboratory for Investigative Neurophysiology, at the University Hospital Center and University of Lausanne, Switzerland, and colleagues wrote.
“Considering the disruptive influence of age-related neurodegenerative conditions such as [mild cognitive impairment] and [Alzheimer’s disease] on visual and auditory systems, sensory dominance patterns are likely clinically important. Aging may push individuals towards being typically more visual/auditory, which in turn may modulate the magnitude or even presence of benefits in multisensory perception tasks. Existing, scant studies employing multisensory detection tasks showed more or less explicitly that healthy older individuals might be overall visually dominant,” they added.
Researchers timed the responses of 98 participants — 18 healthy young adults, 35 healthy older adults, and 18 older adults with mild cognitive decline — to audio or visual stimuli or a combination of both. Tests took place in the participants’ home, a quiet, private room at a university in England, or a private, residential care home.
In the first round of tests, Murray and colleagues found there were generally slower response times in the healthy older adults than the healthy young adults and older adults with mild cognitive impairment. A follow-up test, which researchers conducted “despite no explicit effort on our part to titrate stimulus efficacy,” found that the healthy older adults and the older adults with mild cognitive impairment responded faster to the audio stimuli than the video stimuli vs. the healthy young adults.
“We are particularly excited about this work because it shows how very simple tests can help clinical practice by reaching a wider population, at a lower cost. We are happy that our findings clarify the link between our vision and hearing and their role in supporting memory (dys-)function; it becomes increasingly clear that how preservedour cognitive skills are as we age depends on how intact our senses are,” Murray said in a press release.
"Our findings open the exciting possibility that a simple perceptual task could be a valuable complementary screening and assessment tool for [mild cognitive impairment],” Trudi Edginton, a cognitive neuroscientist and clinical psychologist at City, University of London, added in the press release. – by Janel Miller
Disclosures: Healio Family Medicine was unable to determine authors' relevant financial disclosures prior to publication.
Perspective
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Heather E. Whitson, MD, MHS
This line of research is important because we believe that a major barrier to developing successful treatments for Alzheimer’s disease has been the lack of reliable tools to detect the condition in very early stages. By the time the symptoms of dementia are obvious, the brain has already sustained significant damage. We hope that treatments may be more effective if we could identify individuals in the earliest stages of the disease, when the symptoms may be so subtle that the patients don’t even notice them.
One of the most sophisticated things that our brains do is to manage all the sensory stimuli that we receive. Even though we are not consciously aware of it, our brains process stimuli from multiple sensory organs (eg, eyes, ears, nose), prioritize the input, and use the information to make decisions and react. These authors are investigating whether subtle changes in that very complex process may be an early warning sign for dementia.
An exciting feature of the testing platform that Murray, et al studied is that patients could administer it to themselves, on a computer or iPad, in the privacy of their home. This could help the screen reach more people at a low cost. When tests have to be administered by an examiner, many patients feel nervous and embarrassed (so may avoid screening) and the examiners must have some level of training and proficiency to administer the tests in a reliable way.
Although this is an exciting avenue of research, the screening tool will require further validation before it is ready for use in clinics. The study sample, especially the mild cognitive impairment group, was relatively small. This mild cognitive impairment group was identified based on their scores on a different cognitive screening tool, so we don’t know whether those participants are truly in the early stages of Alzheimer’s disease/dementia or are simply bad test takers.
The groups may have differed on important factors besides cognitive diagnosis that could have accounted for the results seen here. For example, the two groups of older adults were not well-matched in age, so it’s possible that age (not brain pathology) accounted for the difference in performance. Also, the visual ability of the participants was not well-characterized. There is some evidence that vision impairments and cognitive impairments co-occur more often than expected by chance, so it’s possible that the group with lower cognitive scores also had worse visual ability (visual acuity, contrast sensitivity, or visual fields) and in that case, their performance on the task may have been different because of differences in their vision, not due to underlying brain disease.
Bottom line is that the study had some methodological limitations that could be addressed by future research, but it is an exciting area and promising initial results.
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