精神分裂症患者的暴力行为会导致凶杀、人身伤害等恶性事件，对个人、家庭及社会带来危害。Omega-3脂肪酸可以减少暴力、攻击行为，但对精神分裂症患者暴力行为的影响尚不明了。本研究拟采用安慰剂双盲对照试验，探索Omega-3脂肪酸对精神分裂症患者暴力行为的影响，采用PET技术探寻其对中枢5-HT的作用，以了解其改变行为的作用机理。本研究将入组有暴力行为且单一使用利培酮治疗的精神分裂症患者100例，随机分组，一组给予安慰剂，一组给予Omega-3脂肪酸900mg/日（EPA540mg+DHA360mg）,持续3月。在基线、干预第4周、第8周及第12周进行BPRS、PANSS、CGI、MOAS量表评定及血浆EPA、DHA、NE、5-HT及DA浓度，了解Omega-3对暴力行为及单胺类神经递质的影响。在基线及第12周，从2组中随机挑选10例患者进行PET扫描，测定大脑中5-HT1A受体密度及亲和力。

Violent behavior of schizophrenia patient can lead to homicide and hurting other people which will jeopardize people, family and society. Omega-3 fatty acid can decrease violence and aggression,but it is not clear if it has effect on violence of schizophrenia patient. We plan to explore if Omega-3 fatty acid have effect on it by a RCT designed study. We will use PET to explore the influence on serotonin funtion of the brain to understand the mechanism of how Omega-3 fatty acid works. This study will enroll 100 patients of schizophrenia with violent behavior.They will be split into 2 groups randomly. In one group, they will receive one pill of placebo per day, and in the other, they will have one pill of 900mg Omega-3 fatty acid per day, each contains 540mg EPA and 360mg DHA. This intervention will last 3 months.At week 0, week 4, week 8 and week 12, the scale of BPRS, PANSS, CGI and MOAS will be evaluated. Meanwhile, the density of EPA, DHA, NE, DA and 5-HT in blood will be tested.These tests can make us know the influence on violent behavior and Monoamine Neurotransmitter of Omega-3 fatty acid. At week 0 and week 12, 10 patients of each group will be selected randomly to test the density of 5-HT1A receptor in brain.