Relationship between going outdoors daily and activation of the prefrontal cortex during verbal fluency tasks (VFTs) among older adults: A near-infrared spectroscopy study

This study sought to investigate the relationship between going outdoor daily and prefrontal cortex activation during execution of the VFT using near-infrared spectroscopy (NIRS) in community-dwelling older adults. Blood oxygenation changes in left and right prefrontal cortices were measured in twenty older adults (mean age 76.1 ± 6.7 years) by NIRS during VFT performance. In this task, participants were required to pronounce as many nouns as possible beginning with the letters “Shi,” “I,” and “Re.” Changes in oxygenated hemoglobin (oxy-Hb) levels during the VFT were compared between two groups defined by the frequency of going outdoors: daily or non-daily within a week. Participants in both groups exhibited significantly increased oxy-Hb levels in the left and right prefrontal cortices during the VFT compared to a resting baseline condition. After controlling for age and gender, there were significant group-by-condition interactions on oxy-Hb levels with less activation during the execution of the VFT over both cortices in the non-daily group (left: F = 4.76, p = 0.04; right: F = 6.32, p = 0.02). These findings indicate that going outdoors daily is associated with increased activation in the prefrontal cortices during VFT performance in community-dwelling older adults.