ABSTRACT
Introduction: Alzheimer's disease (AD) is neurodegenerative dementia that causes neurovascular dysfunction and cognitive impairment. Currently, 50 million people live with dementia worldwide, and there are nearly 10 million new cases every year. There is a need for relatively less costly and more objective methods of screening and early diagnosis. Methods: Functional near-infrared spectroscopy (fNIRS) systems are a promising solution for the early Detection of AD. For a practical clinically relevant system, a smaller number of optimally placed channels are clearly preferable. In this study, we investigated the number and locations of the best-performing fNIRS channels measuring prefrontal cortex activations. Twenty-one subjects diagnosed with AD and eighteen healthy controls were recruited for the study. Results: We have shown that resting-state fNIRS recordings from a small number of prefrontal locations provide a promising methodology for detecting AD and monitoring its progression. A high-density continuous-wave fNIRS system was first used to verify the relatively lower hemodynamic activity in the prefrontal cortical areas observed in patients with AD. By using the episode averaged standard deviation of the oxyhemoglobin concentration changes as features that were fed into a Support Vector Machine; we then showed that the accuracy of subsets of optical channels in predicting the presence and severity of AD was significantly above chance. The results suggest that AD can be detected with a 0.76 sensitivity score and a 0.68 specificity score while the severity of AD could be detected with a 0.75 sensitivity score and a 0.72 specificity score with ≤5 channels. Discussion: These scores suggest that fNIRS is a viable technology for conveniently detecting and monitoring AD as well as investigating underlying mechanisms of disease progression.
ABSTRACT
BACKGROUND: Multiple Sclerosis (MS) is a neuroinflammatory, neurodegenerative, demyelinating disease that causes cognitive, olfactory, and other neurological dysfunctions. Radiologically Isolated Syndrome (RIS), in which only radiological findings are monitored, is accepted as the preclinical stage of demyelinating disease and is considered an important period for disease pathology. Therefore, in this study, we aimed to evaluate the olfactory and cognitive functions and their clinical correlation in RIS and Relapsing-Remitting MS (RRMS) patients and a healthy control group. METHODS: Our study included 10 RRMS patients, 10 RIS patients, and 10 healthy controls. We conducted an olfactor evaluation via the "Sniffin' Sticks" test. The subjects underwent a neuropsychometric test battery to evaluate cognitive functions, including memory, visuospatial, and executive functions. Depression was evaluated using the Beck depression scale. Fatigue and daily life activity were evaluated using the Fatigue Severity Scale (FSS) and the 36-Item Short Form Survey (SF-36), respectively. Disability assessment was done with the Expanded Disability Status Scale (EDSS). RESULTS: RRMS and RIS patients' olfactory test scores were significantly different from those in the control group (p < 0.05). There was a significant difference between the odor threshold scores of patients in the RRMS and RIS groups. There was a significant correlation between memory-oriented cognitive tests and olfactory tests in the RRMS and RIS groups. CONCLUSION: Olfactory dysfunction can be seen in RIS patients, like in RRMS patients. Cognitive and olfactory dysfunction may be together a sign of degeneration in demyelinating diseases.
