Detection of hypofrontality in drivers with Alzheimer's disease by near-infrared spectroscopy

It is important to appropriately evaluate the driving performance of elderly persons. In the present study, near-infrared spectroscopy (NIRS) was employed to investigate differences of brain function between individuals with Alzheimer's disease (n=12) and healthy elderly controls (n=14) while they were being tested using a driving simulator. Changes of the oxyhemoglobin level in the prefrontal areas of each subject were measured by NIRS during a driving task (collision avoidance). Compared with healthy controls, the Alzheimer's disease group showed a less prominent increase of oxyhemoglobin in the prefrontal cortex during the collision avoidance task. The correlation between delay in braking and changes of oxyhemoglobin was positive in the healthy controls and negative in the Alzheimer's disease group, suggesting that a task-related prefrontal increase of oxyhemoglobin has different implications under normal and pathological conditions. NIRS is a potentially useful tool for real-time monitoring of prefrontal activity during simulated or actual driving.