憂慮對威脅反應之自主神經活動抑制效果檢證

Suppression of Autonomic Nervous System Caused by Worry

憂慮是泛焦慮症的主要症狀之一，對於病態憂慮（pathological worry）的維持，Borkovec等人提出憂慮具有抑制威脅刺激所帶來之威脅反應功能的假設。實徵研究發現，個體在憂慮狀態下相對於非憂慮狀態，其心跳變異（heart rate variability; HRV）明顯受抑制，從而支持此一負增強假設，並推論此一現象是來自副交感神經受到抑制。本研究比較文獻中憂慮與威脅反應的自主神經反應型態，進而推論出憂慮造成的HRV受抑制的現象，可能不止來自於副交感神經受到抑制，交感神經的活動亦可能同時受到抑制。為驗證此一假設，本研究以52位大學生為受試，28位男性，24位女性。實驗採二因子混和設計，受試者被隨機分配為憂慮組、回憶組與控制組，三組受試者皆接受基線期（baseline）、電影期、作業期與回復期等四階段實驗操弄。在基線期，受試被要求靜坐休息。接著在電影期中，以觀看恐怖電影引發受試之威脅反應。作業期中，憂慮組被要求執行憂慮；回憶組被要求回憶影片之影像；控制組則被要求靜坐休息。結果發現，在憂慮組各實驗操弄之組內比較上，受試在的作業期（執行憂慮）之HRV與交感神經活性指標顯著低於電影期；且三組受試在作業期之組間比較上，憂慮組的HRV與交感神經活性指標顯著低於回憶組。此一結果說明，威脅反應之後使用憂慮之心血管指標（HRV）受抑制，主要是與交感神經活動受到抑制的假設得到驗證，但在副交感神經活動上則未獲直接支持的證據。

Pathological worry is a major element of generalized anxiety disorders. Borkovec proposed the negative reinforcement hypothesis to explain the maintenance pathological worry. Borkovec and Hu (1990) examined the inhibition of heart rate variability (HRV) by worry, and argued that this inhibitory effect reflected the suppression of the parasympathetic nervous system. However, a review of the literature indicated that worry also inhibited the activity of the sympathetic nervous system. The aim of this study is to test the suppressive effects of worry on the sympathetic and parasympathetic nervous systems. Fifty-two participants (28 male, 24 female) were randomly assigned to three groups (the worry group, the re-exposure group and the control group) . All participants experienced four experimental stages including baseline, fearful movie, mental task and recovery stage. In the baseline and recovery stages, all of the participants were asked to sit peacefully. In the fearful movie stage, all of the participants saw a fearful movie. In the mental task stage, members of the worry group were asked to read the worrying sentences , members of the re-exposure group were asked to recall aversive movie images, and the members of the control group were asked to sit peacefully. The data showed that the HRV and the sympathetic activity indices of the worry group were lower during the mental task stage than during the fearful movie stage. Moreover, the HRV and sympathetic activity indices of the members of the worry group were also lower than those of the re-exposure group during the mental task stage. The results revealed that HRV and sympathetic nervous activity were inhibited when the subjects adopted worry strategy following exposure to fearful stimulus.