機能的近赤外分光法を用いた主観的認知低下におけるデュアルタスクバイオマーカーの調査

Older adults with subjective cognitive decline (SCD) may be at a greater risk of cognitive impairment than older adults without SCD (i.e., non-SCD). This study examined dual-task changes in cerebral oxygenation and performance to determine whether these changes may be used as a biomarker in older adults with SCD. Older adults with (n = 24) and without SCD (n = 18) completed neuropsychological assessments and finger tapping and working memory dual-tasks. Cognitive and motor performance were measured, and functional near-infrared spectroscopy (fNIRS) was used to measure changes in prefrontal cortex oxygenation (∆HbO2, ∆HbR). Repeated measures ANOVAs revealed greater ∆HbO2 during the n-back dual-task compared to the single motor (p = .01) and cognitive (p = .04) conditions. Slower responses (p = .002) and less accurate (p = .024) and more variable (p = .001) finger tapping were observed during the dual compared to single tasks. Within the SCD group, ∆HbO2 was greater during the dual compared to single cognitive condition (p = .002) and between the SCD and non-SCD groups (p = .016). Within the SCD group, finger tapping was more accurate during the single compared to dual-task (p = .04). Cognitive accuracy was also higher during the single compared to dual-task condition in the SCD (p < .001) and non-SCD (p = .005) groups. Neural compensation and inefficiency were observed in older adults with SCD: n-back performance was maintained but double number sequence performance declined despite increased ∆HbO2. Longitudinal evidence is needed to determine whether these mechanisms can be used as biomarkers for progressive cognitive impairment in SCD.