This dissertation, "Biopsychosocial Implications of Heroin Addiction" by Lai-fung, Gordon, Cheng, 鄭禮鋒, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Heroin abuse is devastating to both the individual abusers and society. Owing to its ability to elicit rapid feelings of euphoria and transcendent relaxation, coupled with adverse withdrawal effects, it is one of the most addictive illicit drugs of abuse. The severe and persistent socio-economic detriment caused by heroin abuse signifies an urgent need for understanding how this substance affects abusers. Currently, scientific research into the biopsychosocial functioning of heroin abusers is limited. This thesis presents a series of three studies that sought to contribute to our understanding of how biopsychosocial functioning may be influenced by the abuse of heroin. This thesis contains three studies that drew on a large-scale data collection process, involving the collection of neurobiological, psychosocial, molecular, and neurocognitive measures in both abstinent heroin abusers and matched healthy controls. Study One aimed to identify the neurobiological deficits in relation to heroin abuse. It was revealed that heroin abuse was associated with widespread brain structural atrophy, and such atrophy was more profound with a more severe heroin abuse profile. Study Two aimed to identify the neurobiological substrates of the heroin abusers' personality traits. It was revealed that the heroin abusers' pathological sensation seeking trait was underpinned by structural integrity of the midbrain and the functional connectivity between the midbrain and the prefrontal cortex. Furthermore, the dorsolateral and ventromedial prefrontal cortices were connected in differential ways with the midbrain in relation to heroin abusers' sensation seeking tendency. Finally, Study Three aimed to examine an untested hypothesis that the abuse of heroin accelerates the aging process. It was revealed that heroin abusers had a significantly low telomerase activity level, which reflected acceleration of cellular aging. Moreover, heroin use and telomerase activity interacted to impact on brain structures and functional networks that are closely linked with aging. These brain functional networks were found to correlate with behavioural performance in the respective cognitive domains, further supporting the behavioural relevance of these abnormal brain networks. Altogether, these findings have yielded a convergence of understanding of the detrimental effects of heroin use on its abusers. Theoretically, the current findings support the neurobiological models that assign the prefrontal cortex as the core neuropathology of drug addiction, and also recognize the importance of investigating into brain regions that have incidentally but frequently been found to be influenced by the abuse of heroin. Clinically, the current findings suggest new directions for the assessment, conceptualization and interventions for people affected by drug addiction. These implications pave the way for studies that seek to further understand and remediate the biopsychosocial sabotage caused by substance abuse. DOI: 10.5353/th_b5334872 Subjects: Heroin abuse - Pyschological aspects