To compare the prefrontal cortex activation between normal cognitive aging, amnestic mild cognitive impairment, and early Alzheimer’s disease using functional near-infrared spectroscopy (FNIRS) in English-Speaking Malaysian

Abstract

Background: Alzheimer’s disease (AD) is a chronic progressive neurodegenerative brain that can occur in middle or old age. The current assessment tools are time-consuming, proneness to subjectivity, and the scores can be influenced by education, socio-economics status and gender. The advantages of functional near-infrared spectroscopy (fNIRS) over other neuroimaging modality as well as its sensitivity in measuring haemodynamic changes represent a promising approach in this study. Methods: the prefrontal cortex of healthy controls (HC), amnestic mild cognitive impairment (aMCI) and early (AD) was studied. Each HC was individually matched by age and gender without personal or family history of psychiatric disorders. Categorical verbal fluency task (VFT) was used as activation task in conjunction to fNRIS. Results: the HC demonstrated significantly greater number of word in all three categories of VFT, followed by aMCI and early AD; saving for “animal” category between aMCI and early AD. MCI demonstrated greatest level of PFC activation, followed by HC and early AD; significantly greater chances in the level of oxy-Hb was found in aMCI compared to early AD> Conclusion: Categorical VFT derived in this study may represent an effective activation task to be in conjunction with fNRIS. The numbers of activated probes may represent a better indicator for differentiation between the three groups, as compared to the level of oxy-Hb. The activation level of right pfc is crucial in distinguish between MCI and early AD. Avenues for future studies included: larger sample size, exclusion of secondary comorbidities, and investigation into other brains regions.