Assessment of Functional Near-infrared Spectroscopy by Comparing Prefrontal Cortex Activity

Abstract

Many studies have suggested the possibility of using functional near-infrared spectroscopy (fNIRS) devices as neuroimaging tools in various patients. We aimed to evaluate whether fNIRS to measure the prefrontal cortex (PFC fNIRS) is suitable as a screening tool for cognitive impairments. Sixty participants, divided into normal, mild cognitive impairment, and dementia groups, were instructed to wear an fNIRS device during cognitive assessments to assess whether there is a significant difference in the PFC activity between the groups. A significant difference in PFC activity between the groups was observed during the verbal fluency test. Moreover, the PFC activity during the verbal fluency test significantly correlated with the existing cognitive screening tool score. These results suggested that PFC fNIRS can be used as a cognitive impairment screening tool for mild cognitive impairment and dementia. A larger sample size is needed to validate the potential of PFC fNIRS as a cognitive impairment screening tool.

A systematic review of near-infrared spectroscopy in dementia

“…Schematic representation of the semantic verbal fluency task. Right Healthy controls have higher pre-frontal cortex activity compared to both mild cognitive impairment and dementia groups [27]. (D) Left .…”

“…Interestingly resting state oxygenation during such challenges reflects oxygenation increases caused by acupuncture therapy and galantamine treatment in MCI [20], VaD [21], [22], and AD [23]. In contrast, purely resting state data does not appear to differentiate between AD [24]–[26] and MCI [27], and controls.…”

“…Subjects are presented with a sequence of letters and must indicate whether the presented letter was the same as that just before (one-back) or before last (two-back). Two studies observed blunted haemodynamic responses in MCI [39], [40], with a gradation from healthy controls to MCI to AD [24], whereas three found no difference in functional response [27], [41] or connectivity [31] between MCI and controls. Interestingly, one study identified hyperactivation in MCI compared to controls [42].…”

“…Several studies specifically focused on MCI, with varied results. A few studies observed hypoactivation [27], [40], [43], [73] (Fig 3c), particularly in the right parietal region [66], and reduced inter-hemispheric connectivity [31]. However, upon classifying between MCI and healthy controls using the HbO signal, the VFT was not as stable an indicator of MCI as the n-back task [39].…”

“…However, upon classifying between MCI and healthy controls using the HbO signal, the VFT was not as stable an indicator of MCI as the n-back task [39]. In support of a lack of diagnostic potential of the VFT, Baik et al [27] did not identify differences between MCI and AD. In line with this, the association between the magnitude of the haemodynamic response and clinically-relevant features such as MMSE score [66], [68], [74], or behavioural performance [62], [65], [75], [76], is unclear.…”