Attentional Bias in Obsessive-Compulsive Disorder : A Time Course Analysis

強迫性疾患（obsessive-compulsive disorders , OCD），又稱強迫症，主要有兩種核心症狀，分別為強迫思考（obsession）與強迫行為（compulsion）。本研究的目的在探討不同症狀類型的強迫性疾患的注意偏誤特性與歷程，並比較其與廣泛性焦慮疾患之差異。本研究之參與者來自北部某精神疾患專科醫院之門診病患與一般社區公民。前者主要由精神科醫師轉介具強迫性疾患與廣泛性焦慮疾患診斷之門診初診病患。本研究共計50位參與者，包括13位強迫檢查症狀患者，13位強迫清潔症狀患者，10位廣泛性焦慮疾患患者，以及14位一般社區公民。本研究以Koster（2004）提出的點偵測作業（dot-probe task）派典與注意偏誤指標（attentional bias index），探討注意偏誤的兩個主要機制，即注意警覺偏誤與注意轉移困難偏誤。以此二偏誤指標為依變項，以貝克憂鬱量表（BDI）之得分為共變項，進行4（組別：強迫症檢查症狀組、強迫症清潔症狀組、廣泛性焦慮疾患組、一般社區公民組） × 3（刺激字詞類別：強迫檢查字詞、強迫清潔字詞、正向情緒字詞）× 3（刺激呈現時間：100毫秒、500毫秒、1000毫秒）三因子混合設計之重複量數共變數分析。研究結果顯示，當面對威脅刺激時，強迫性疾患之注意偏誤歷程，在短刺激呈現時間會出現注意警覺偏誤現象，而後，隨刺激呈現時間增長，在中、長刺激呈現時間，其注意偏誤轉為注意轉移困難現象。此外，不同症狀類型之強迫性疾患在面對其核心症狀相關的威脅性刺激時，有近似的注意偏誤歷程，但對非核心症狀相關的刺激則有不同的注意歷程。另外，在面對正向刺激字詞時，亦有不同的注意偏誤歷程，僅強迫檢查症狀組對正向字詞在短刺激呈現時間裡，會有注意警覺偏誤現象，而在中、長刺激呈現時間則會有注意轉移困難偏誤現象；而強迫清潔症狀組則無論在短、中、長刺激呈現時間均不會出現注意警覺偏誤及注意轉移困難偏誤現象。此外，強迫檢查症狀組與廣泛性焦慮疾患組，對正向刺激字詞有近似的注意偏誤歷程。本研究的結果可用以說明不同類型之強迫性疾患，其核心症狀的同質性與異質性。本研究藉由比較不同類型之強迫性疾患，及其與廣泛性焦慮疾患間之注意偏誤歷程差異，據其結果可以擬定臨床之介入策略與治療方法。Obsessive-compulsive disorder, also known as OCD, has two core symptoms, obsession and compulsion. The purpose of this study was to investigate the characteristics and course of attentional bias between different types of OCD, and compare the bias differences with generalized anxiety disorder (GAD). Participants in this study came from a mental illness hospital outpatients and community citizens. The patients with OCD or GAD were referred by a psychiatrist. There were a total of 50 participants, including 13 OCD with checking symptoms, 13 OCD with cleaning symptoms, 10 GAD, and 14 community citizens. Koster’s (2004) dot-probe task design and attentional bias index were adopted to measure two major attention mechanisms of the attentional bias, namely, attention vigilance and attention disengagement difficulty. With these two bias indices as the dependent variables, and Beck Depression Inventory (BDI) scores as the covariate, a 4 (groups: OCD with checking symptoms, OCD with cleaning symptoms, GAD, general community citizens) × 3 (stimulus word: checking words, cleaning words, positive emotion words) × 3 (stimulus exposure time: 100 ms, 500 ms, 1000 ms) mixed factorial design was conducted. The results showed that when faced with the threat stimuli, OCD patients revealed vigilant attention bias in the short stimulus exposure time, then, turned to attention disengagement difficulty in the middle and long stimulus exposure time. In addition, there was similar course of attentional bias in the two subtypes of OCD when they faced threats in accordance with their core symptom-related stimuli, but for the non-core symptom-related stimuli, they showed different attention process. Besides, in face of positive stimulus words, there was different attentional bias course between the two groups. Only OCD with checking symptoms revealed vigilant attention bias in the short exposure time, and difficulty disengagement in the medium and long stimulus exposure time, while OCD with cleaning symptoms did not show vigilant attention bias or attention disengagement difficulties in any exposure time. In addition, OCD with checking symptoms and GAD had similar attentional bias course for positive stimuli words. The results of this study can be used to illustrate the homogeneity and heterogeneity of the core symptoms in the different types of OCD. By comparing attention bias between types of OCD and GAD, the results of the present study suggest some possibilities to develop clinical intervention strategies and treatment methods