Schizophrenia is a serious long-term psychotic disorder marked by positive and negative symptoms, severe behavioral problems and cognitive function deficits. The cause of this disorder is not completely clear, but is suggested to be multifactorial, involving both inherited and environmental factors. Since human brain regulates all behaviour, studies have focused on identifying changes in neurobiology and biochemistry of brain in schizophrenia. Brain is the most lipid rich organ (approximately 50% of brain dry weight). Total brain lipids is constituted of more than 60% of phospholipids, in which docosahexaenoic acid (DHA, 22:6n-3) is the most abundant (more than 40%) polyunsaturated fatty acid (PUFA) in brain membrane phospholipids. Results from numerous studies have shown significant decreases of PUFAs, in particular, DHA in peripheral blood (plasma and erythrocyte membranes) as well as brain of schizophrenia patients at different developmental phases of the disorder. PUFA deficiency has been associated to psychotic symptoms and cognitive deficits in schizophrenia. These findings have led to a number of clinical trials examining whether dietary omega-3 fatty acid supplementation could improve the course of illness in patients with schizophrenia. Results are inconsistent. Some report beneficial whereas others show not effective. The discrepancy can be attributed to the heterogeneity of patient population. In this review, results from recent experimental and clinical studies, which focus on illustrating the role of PUFAs in the development of schizophrenia were examined. The rationale why omega-3 supplementation was beneficial on symptoms (presented by subscales of the positive and negative symptom scale (PANSS), and cognitive functions in certain patients but not others was reviewed. The potential mechanisms underlying the beneficial effects were discussed. Omega-3 fatty acid supplementation reduced the conversion rate to psychosis and improved both positive and negative symptoms and global functions in adolescents at ultra-high risk for psychosis. Omega-3 fatty acid supplementation could also improve negative symptoms and global functions in the first-episode patients with schizophrenia, but improve mainly total or general PANSS subscales in chronic patients. Patients with low PUFA (particularly DHA) baseline in blood were more responsive to the omega-3 fatty acid intervention. Omega-3 supplementation is more effective in reducing psychotic symptom severity in young adults or adolescents in the prodromal phase of schizophrenia who have low omega-3 baseline. Omega-3 supplementation was more effective in patients with low PUFA baseline. It suggests that patients with predefined lipid levels might benefit from lipid treatments, but more controlled clinical trials are warranted.

中文翻译：

---

补充 omega-3 脂肪酸对精神分裂症的有益作用：可能的机制。


精神分裂症是一种严重的长期精神障碍，以阳性和阴性症状、严重的行为问题和认知功能缺陷为特征。这种疾病的病因尚不完全清楚，但被认为是多因素的，涉及遗传因素和环境因素。由于人类大脑调节所有行为，因此研究重点是确定精神分裂症患者大脑神经生物学和生物化学的变化。大脑是脂质最丰富的器官（约占大脑干重的 50%）。脑总脂质由60%以上的磷脂组成，其中二十二碳六烯酸（DHA，22:6n-3）是脑膜磷脂中含量最丰富（超过40%）的多不饱和脂肪酸（PUFA）。大量研究结果表明，处于不同发育阶段的精神分裂症患者的外周血（血浆和红细胞膜）以及大脑中的 PUFA，尤其是 DHA 显着下降。 PUFA 缺乏与精神分裂症的精神病症状和认知缺陷有关。这些发现引发了一系列临床试验，检验饮食中补充 omega-3 脂肪酸是否可以改善精神分裂症患者的病程。结果不一致。有些报告有益，而另一些则显示无效。这种差异可归因于患者群体的异质性。在这篇综述中，我们对最近的实验和临床研究的结果进行了检查，这些研究的重点是说明多不饱和脂肪酸在精神分裂症发展中的作用。 回顾了补充 omega-3 对症状有益的基本原理（由阳性和阴性症状量表 (PANSS) 的子量表以及某些患者而非其他患者的认知功能表示）。讨论了有益效果的潜在机制。补充 Omega-3 脂肪酸可降低精神病转化率，改善精神病超高风险青少年的阳性和阴性症状以及整体功能。补充 Omega-3 脂肪酸还可以改善首发患者的阴性症状和整体功能。患有精神分裂症，但主要改善慢性患者的总体或一般 PANSS 量表，血液中 PUFA（特别是 DHA）基线较低的患者对 Omega-3 脂肪酸干预更敏感，可以更有效地减轻精神病症状的严重程度。处于精神分裂症前驱期的 omega-3 基线较低的年轻人或青少年。补充 Omega-3 对于 PUFA 基线较低的患者更有效。它表明具有预定血脂水平的患者可能会受益于血脂治疗，但需要进行更多对照的临床试验。