正念在治療憂鬱症失樂症狀所扮演的角色：心理機制的探討

目前研究或臨床上關注的憂鬱症多集中在憂鬱症的負向症狀上，然而憂鬱症的正向情緒缺損也是憂鬱症很重要的症狀之一，後者又被稱為失樂症狀（anhedonia）。本研究將憂鬱症的失樂症狀分為對於過去回憶、現在感受、未來預期三個面向，提出可能影響正向情緒的心理機制，並探討在經過八週的正念認知治療後，憂鬱症的失樂症狀、生活品質、憂鬱症狀是否改善。由於憂鬱症和負向記憶的可得性增加以及正向記憶的可得性減少有關，本研究推論憂鬱症患者在回憶過去的正向事件時，會有負向記憶侵入的情況，導致正向情緒較低且不易維持。另外，憂鬱症狀可以被看作是「對於實現目標的無望感」的一種展現，因此，本研究推論這種對未來的無望感會導致在預期未來的正向事件時，憂鬱症患者會有較低的正向情緒。另外，研究指出低的感覺尋求和身體上的失樂症狀有關，因此，本研究推論對於身體感覺的覺察不足會導致憂鬱症患者對於現在的正向刺激產生正向情緒不足的情況。本研究將憂鬱症患者隨機分派至憂鬱實驗組（正念認知治療組）及憂鬱等待組，並招募社區一般民眾作為一般控制組，分別為29人、21人、與29人。他們於正念認知治療前、中、後三個時間點，接受憂鬱、焦慮、失樂、生活品質、自動化負向思考、無望感、身體感覺、正念等自陳式問卷，並以正向情緒誘發作業檢驗其失樂症狀變化。研究結果顯示，正念認知治療可以有效改善憂鬱症的憂鬱、焦慮、失樂以及心理範疇的生活品質，並降低自動化負向思考的相信程度和無望感受。本研究進一步發現無望感在正念認知治療與失樂症狀的改變間有完全中介效果，對自動化負向思考的相信程度在正念認知治療與憂鬱症狀的改變間有部分中介效果。另外，本研究也發現正念認知治療透過改善自動化負向思考，繼而影響改善無望感，並導致失樂症狀的改善；正念認知治療透過改善無望感，繼而影響改善自動化負向思考，並導致憂鬱症狀的改善。易言之，本研究結果說明了正念認知治療為治療憂鬱症失樂症狀的有效介入方式，可以做為未來憂鬱症患者進一步治療的選擇。在正念認知治療產生療效的心理機制方面，亦發現正念認知治療對於改善失樂與憂鬱症狀的獨特路徑，可供未來臨床工作者在制定治療計畫與療效評估時的重要參考。

關鍵字

失樂症狀；評價；身體感受；無望感；正念

並列摘要

Research and therapy on depression to date have predominantly focused on negative emotional experiences. However, a deﬁcit in the ability to experience positive emotions is one of the core symptoms of depression, referred to as anhedonia. The present research enumerates three domains of anhedonia in depression, namely, past recollection, present experiences, and future expectation. Accordingly, this study postulates possible psychological mechanisms on how positive emotions are impacted under the above three domains and investigate whether anhedonia and the quality of life in depression will be improved after the 8-week mindfulness-based cognitive therapy (MBCT) through these mechanisms. Concerning possible psychological mechanisms, depression is correlated with increasing accessibility of negative memories and decreasing accessibility of positive memories. Many research has also suggested that depressed patients experienced intrusive memories at a level equivalent to patients with posttraumatic stress disorder. Therefore, the present study infers that depressed patients experience negative intrusive memories when trying to recall positive memories, which leads to lowered level of positive emotions and difficulty to remain in positive emotions. Additionally, depression can be seen as a manifestation of hopelessness towards the attainment of goals. Henceforth, this study infers that due to their hopelessness towards future, when depressed patients anticipate positive events, they will experience lowered positive emotions. Lastly, as research suggested that lowered levels of sensation seeking may be an indicator of physical anhedonia, this study infers that when depressed patients encountering positive stimuli, the avoidance of body sensations will lead to their lessened positive emotions. Depressed patients were randomized to continue with treatment as usual (n = 21) or to receive MBCT additionally (n = 29). We also recruited community participants as normal control group (n = 29). Self-report inverntories and a positive emotion provoked test were assessed at three time points corresponding to the baseline, middle and end phases of the the MBCT group. The results revealed significant improvements in depressive symptoms, anhedonia, psychological domains of life, anxiety level, believability in automatic negative thinking, and degree of hopelessness in the MBCT group. In addition, the mediation analyses on the mechanisms of MBCT for depression suggested that after mindfulness intervention, improvements of anhedonia was partially mediated by decreasing believability in automatic negative thinking, and improvements of hopelessness was completely mediated by decreasing depression symptoms. Furthermore, we also found indirect influences mediated by two subsequent variables. Specifically, there was one indirect influence of MBCT via decreasing believability in automatic negative thinking and decreasing of hopelessness on improvements of anhedonia. And, there was a positive significant indirect influence of MBCT on decreasing depression symptoms mediated by improvements of hopelessness and improvements of believability in automatic negative thinking. The findings suggest the MBCT program can be considered as a further treatment option for major depression. According to our psychological mechanism of MBCT, the unique pathways for improving the symptoms of anhedonia and depression can be used as important references for clinicians in treatment plan and efficacy evaluation.