缺乏變革動機被廣泛地視為治療藥物濫用的其中一個主要障礙，本研究旨在針對以上問題，了解影響香港藥物濫用者斷藥動機的心理社會因素。跨理論模式 (Transtheoretical Model) 的轉變階段概念被用作斷藥動機的指標。而計劃行為理論 (Theory of Planned Behavior)，因為可以有效預測廣泛的健康相關行為，故被採納為研究斷藥動機的主要理論架構。本文研究計畫行為理論中的構念（即態度、主觀規範和自我意識行為控制）如何影響人的斷藥動機。本文也調查了在研究初始時的斷藥動機與其他心理社會因素，如何影響受訪者在三個月後的斷藥狀態及濫藥的頻率。影響行為抑制及情緒不穩的性格因素也會被探討，以了解它們如何影響斷藥動機及藥物濫用。 / 本文中的受訪者來自醫院管理局的藥物濫用診所，康復機構轄下的中途宿舍或社會服務中心。共有183位過去或現在有濫用藥物背景的受訪者參與研究，當中有87位受訪者(47.5%)完成了三個月後的跟進電話訪問。 / 本文使用路徑分析，發現計劃行為理論裡中的態度、主觀規範及自我意識行為控制，會透過行為意欲影響斷藥的轉變階段。此外，研究亦部份支持結合了計劃行為理論與轉變階段概念的修正綜合斷藥動機模型，可以預測受訪者在三個月後的濫藥頻率。斷藥的自我效能被發現為影響硏究初始時的斷藥動機及三個月後濫藥頻率的重要因素。另外，研究亦証明斷藥動機是預測三個月後的斷藥狀態及濫藥頻率的關鍵因素。影響行為抑制的性格因素透過斷藥的自我效能和轉變階段對濫藥頻率有輕微的間接影響。本文會闡述以上發現對藥物濫用治療的影響。 / Since lack of motivation for change has been generally regarded as one of the major obstacles in treating substance use problems, the present study aimed to address this issue by investigating the psychosocial factors in determining motivation for abstinence among persons with substance use problems in Hong Kong. The stage of change construct of the Transtheoretical Model (TTM) was used as an indicator of motivation for abstinence. The Theory of Planned Behavior (TPB) with its well established usefulness for the prediction of a wide-range of health-related behaviors was adopted as a major theoretical framework. The present study investigated whether the constructs of TPB (i.e. attitude, subjective norm, and perceived behavioral control) influenced one's motivation to abstain from substance use. It also examined how motivation for abstinence and other psychosocial variables at baseline influenced drug abstinence status and drug use frequency at 3 month follow-up. The potential influences of personality factors of behavioral disinhibition and emotional instability in influencing motivation for drug absitnence and drug use behavior were also examined. / Participants were recruited from substance abuse treatment clinics, halfway houses and social services centres run by rehabilitation organisations. 183 participants with past or current history of substance use problems participated in the main study. 87 of them (47.5%) completed the follow-up phone survey 3 months later. / The applicability of the TPB variables of attitude, subjective norm, and preceived behavioral control in predicting stage of change through the mediation of behavioral intention was supported in a series of path analyses. In addition, the applicability of a revised integrated model on motivation for drug abstinence, which integrated the TPB model with the stage of change construct, in the prediction of drug use frequency at follow-up was partially supported in path analyses. Drug abstinence self-efficacy was found to be a very important factor in predicting both motivation for abstinence at baseline and drug use frequency at follow-up. In addition, the pivotal role of motivation for abstinence in the prediction of drug abstinence status and drug use frequency at follow-up was supported. Among the 2 personality variables, only behavioral disinhibition showed weak indirect effect on drug use frequency at follow-up through the mediation of drug abstinence self-efficacy and stage of change. The implications of the findings for intervention were discussed. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wong, Sau Ying. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 115-145). / Abstracts also in Chinese; appendix in Chinese.