- Abnormal functionality in regions of the brain that process speech sound, the brainstem and auditory cortex, could be a new potential predictor of early dementia.
- This decline in brain function related to communication could be the first sign that manifests before the individuals become aware of these problems.
- This functional biomarker could help to identify people who should be monitored more closely for their risk of developing dementia.
Though cognitive impairment like decline in memory and thinking problems are often an early indicator of dementia and Alzhemer's disease, older adults should be vigilant about their hearing and communication problems.
New findings by researchers from Baycrest Centre for Geriatic Care and University of Memphis suggest that abnormal functionality in regions of the brain that process speech, the brainstem and auditory cortex, could be a new potential predictor of early dementia.
This abnormal function decline in brain function related to communication could be the first sign of dementia that manifests before the individuals become aware of these problems.
The study examined 23 older adults between the ages of 52 and 86 years with no known history of neurological or psychiatric illnesses with similar hearing acuity.
Participants were separated into two groups based on their results on a dementia screening test.
They were made to watch a video and the brain activity in the brainstem was measured. While participants were identifying vowel sounds, brain activity in the auditory cortex was measured.
Researchers combined both sets of brain activity, using statistical methods, to predict mild cognitive impairment.
"This opens a new door in identifying biological markers for dementia since we might consider using the brain's processing of speech sounds as a new way to detect the disease earlier," says Dr. Claude Alain, the study's senior author and senior scientist at Baycrest's Rotman Research Institute (RRI) and professor at the University of Toronto's psychology department.
The brain activity within the brainstem of these older adults demonstrated abnormally large processing of speech sound within 7-10 milliseconds of the signal hitting the ear. This could be sign of greater communication problems in the future.
"Losing the ability to communicate is devastating and this finding could lead to the development of targeted treatments or interventions to maintain this capability and slow progression of the disease." Alain added.
"When we hear a sound, the normal aging brain keeps the sound in check during processing, but those with MCI have lost this inhibition and it was as if the flood gates were open since their neural response to the same sounds were over-exaggerated," says Dr. Gavin Bidelman, first author on the study, a former RRI post-doctoral fellow and assistant professor at the University of Memphis.
"This functional biomarker could help identify people who should be monitored more closely for their risk of developing dementia." Bidelman added.
The researchers used electroencephalogram (EEG) to measure electrical activity using in these brain regions. This technique also helped predict mild cognitive impairment (MCI), with 80% accuracy.
This test could be developed into a cost-effective and objective diagnostic assessment for older adults.
"MCI is known to cause changes in different senses, such as vision or touch," says Dr. Alain. "If we could incorporate these changes into a wireless EEG test, we could combine all this information and develop a better biomarker. One day, doctors could administer a short, 10-minute assessment and instantly provide results."
"This could offer a new diagnostic assessment that tests a person's cognitive abilities, such as their ability to communicate, and objectively measure physiological changes in the brain that reflect early signs of dementia," says Dr. Bidelman.
The study is published online in the Journal of Neuroscience.
- Claude Alain et al. Mild cognitive impairment is characterized by deficient brainstem and cortical representations of speech. Journal of Neuroscience; (2017) doi.org/10.1523/JNEUROSCI.3700-16.2017