Abstract
Previous studies have reported that increased smartphone use is associated with cognitive function decline. To date, the hemodynamics in the prefrontal cortex (PFC) due to smartphone addiction have not been elucidated. This study aimed to examine the relationship between smartphone addiction and PFC activity. After measuring the smartphone usage time using an application, we evaluated smartphone addiction, depression, and sleep quality using questionnaires. In addition, to assess PFC activity, which is responsible for working memory, we measured cerebral blood flow in the PFC during verbal and spatial working memory tasks (VWM and SWM, respectively). Cerebral blood flow was measured in terms of the oxygenated hemoglobin levels using a 16-channel (Ch) near-infrared spectrometer. Data from 79 participants were analyzed. First, we found that smartphone addiction was positively correlated with depression, but not with the smartphone usage time and sleep quality. Second, after excluding the influence of depression, we found that smartphone addiction was negatively correlated with cerebral blood flow in Ch10 during VWM and in Ch6, 7, and 10 during SWM. These Chs correspond to the frontopolar cortex (FPC), which is part of the PFC, suggesting that smartphone addiction may reduce FPC activity.