Evaluating the utility of fNIRS in detecting and diagnosing AD/ADRD

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Project Abstract The US Census Bureau projects that people over the age of 65 years will number 77 million by 2034, indicating a rapidly aging population. The World Health Organization projects a steady increase in the number of individuals with dementia, with 82 million individuals by 2030. Further, according to the Alzheimer’s Association, an estimated 6.5 million people are living with Alzheimer’ dementia, and the percentage of dementia increases with age, 5.0% of people age 65 to 74, 13.1% of people age 75 to 84, and 33.2% of people age 85 and older have Alzheimer’s dementia 1. While there are a cluster of neurodegenerative disorders that constitute dementia 2, mild cognitive impairment (MCI)3, fronto-temporal dementia spectrum disorders 4, 5 that includes primary progressive aphasia 6, 7 and posterior cortical atrophy 8 are all characterized by language, cognitive and memory deficits. All these individuals experience changes or subtle decline in their everyday abilities that are hard to detect, however, once diagnosis is made these symptoms have deteriorated significantly. It is therefore important to rigorously evaluate approaches that can detect and diagnose degenerative disorders early and during daily activities where instances of abnormalities and changes first arise. To be able to detect and diagnose degenerative disorders, we need to be able to continuously track human brain function and behavior in the Everyday World. In the parent grant, we are developing the “Neuroscience in the Everyday World” hardware, an fNIRS/EEG system with an integrated computer vision and eye tracking device to measure brain and behavioral function in healthy adults, individuals with stroke or Parkinson’s Disease as they go about their everyday lives. In this supplement, we aim to evaluate the utility of fNIRS as a tool to examine the neurophysiological mechanisms underlying early language and cognitive changes in individuals with AD/ADRD. In Aim 1, we will extend our wearable fNIRS system used to measure everyday interaction, attention, working memory and walking in healthy adults, post-stroke individuals with aphasia to adults with AD/ADRD and MCI. Building on our previous work, we will evaluate cortical activity during conversation, walking and perceptual tasks in adults with AD/ADRD and MCI. We expect to detect differences in the fNIRS signal between ADRD and healthy age-matched controls (collected as part of the parent grant) as they perform these behavioral tasks. In Aim 2, we evaluate the relationship between behavioral (e.g., language and cognitive) function and neural signatures in the fNIRS profiles in adults with AD/ADRD relative to healthy controls. We will compare behavioral performance on the task measures with the magnitude of the fNIRS signal, hypothesizing that individuals with AD/ADRD with higher behavioral performance will show greater fNIRS signal magnitude relative to the ones with poorer behavioral performance. The proposed work has a high impact as it allows the examination of neural and behavioral markers of early neurological dysfunction during everyday activities such as interaction or dual task walking (multi-tasking while walking) leading to future research on understanding the mechanisms of early neurological changes in AD/ADRD.