認知－運動課題による痛覚感受性への影響

抄録

   Background: Physical exercise may facilitate the improvement of pain–associated symptoms in patients with chronic pain. Moreover, motor cortex activation causes pain reduction via actions in pain–related central nervous system areas. Thus, physical exercise is believed to activate this pain control mechanism in the central nervous system. Cognitive tasks may also modulate pain, as these pain–related areas of the central nervous system play a vital role in cognitive functions. However, the mechanisms underlying pain reduction when performing cognitive tasks are unclear. Here, we aimed to investigate the effect of a cognitive–motor task on pain control.
   Methods: Thirty healthy subjects participated in this study. All participants performed 3 different tasks: a motor task involving the pressing of a button on a keyboard with the dominant hand (M task), a cognitive task involving thinking about the answers to the Stroop task (C task), and a cognitive–motor task involving the pressing of a button on a keyboard cor­responding to the answer to the Stroop task (CM task). Furthermore, the participants were classified according to the rate of correct answers given on the CM task (low rate, LS group; high rate, HS group). The pressure pain threshold (PPT) of the non–dominant forearm was estimated, and electro­encephalography (EEG) was performed over the frontal region to determine the attention and concentration given to each task. The EEG data were used to analyze the power of the theta, alpha, and beta frequency bands.
   Result: The PPT of the CM task significantly increased after the task period compared to that before the test, and was significantly higher compared to that of other tasks after the task period. Moreover, the power of the theta and alpha bands for the CM task significantly increased during the task period compared to that before the task, and was significantly higher compared to that of the other tasks during the task period. Moreover, the PPT of the HS group was significantly higher compared to the LS group after the task period, whereas the power of the theta and alpha bands significantly increased during the task period in the HS group.
   Conclusion: Compared to the motor or cognitive task alone, the CM task significantly reduced pain sensitivity. Moreover, a significant increase in the power of the theta and alpha bands was only noted in the CM task. Thus, the cognitive–motor task that required attention and concentration was effective in pain inhibition.