心理疾病与胃肠道：(一)抑郁症与肠道微生物
目前临床上一般把疾病分为生理疾病和心理疾病，分别在不同的科室甚至不同的医院由各自专门的医生进行治疗，甚至同时患有生理疾病和心理疾病的人可能需要去两个不同的地方进行治疗。
但心理疾病和生理疾病有很大的共病性，心理疾病患者往往伴随着便秘，腹泻，胃胀等胃肠道症状，但这些却往往被心理医生所忽视。除了胃肠道疾病，其他慢性疾病患者（如代谢性疾病像糖尿病，过敏性疾病，自身免疫性疾病等）的心理疾病（如抑郁焦虑）发病率也明显升高。
最新的科研证据显示，心理疾病的根源可能在于肠道微生物，多数心理疾病可能本质上是胃肠道疾病，针对肠道微生物来治疗心理疾病，可能是未来精神病学发展的有力方向[1-4]。而能够改善情绪和认知，给精神疾病患者带来益处的好细菌，也被称之为益心菌（psychobiotics）[5-7]。下面将简单介绍各种心理疾病与肠道微生物的关系。
1. 抑郁症与肠道微生物抑郁症是一种以显著而持久的情绪低落、兴趣减退为主要临床特征的精神疾病。患者往往伴随着愉快感缺乏及意志行为减退，还包括有不适宜的负罪感、自杀念头、注意力不集中、失眠、食欲障碍等症状。目前，抑郁症已经成为全球最常见的精神疾病，影响着3亿5千万人的生活, 平均每5个人中就可能有一个在生命的某一阶段遭受抑郁的折磨[8, 9]。传统观点认为，抑郁症是一种异质性疾病，由遗传和环境应激的累积效应引起，易感个体遭受应激从而出现抑郁[10]。但最新观点发现，抑郁症的根源可能在肠道微生物，肠道微生物异常可能是隐藏在应激和基因之下导致抑郁症的根本原因。1.1 与健康对照相比，抑郁患者的肠道微生物发生了显著改变[11-13]。即使经过治疗，心理量表指数已经恢复正常的抑郁患者，菌群结构仍然明显不同于健康个体，这可能是抑郁症易复发的重要原因。1.2 把抑郁患者的粪便菌群移植给无菌小鼠，小鼠表现出明显的抑郁症状（包括行为认知表现、生理异常、代谢异常和菌群异常）[14, 15]。1.3 补充益生菌，能明显改善抑郁症状，甚至有研究发现一些益生菌（如瑞士乳杆菌特定菌株）的效果优于抗抑郁药[16-18]。图片来自网络。明日预告：心理疾病与胃肠道：(二)焦虑症与肠道微生物参考文献：1 Kennedy P J, Murphy A B, Cryan J F,et al. Microbiome in Brain Function and Mental Health. Trends in Food Science& Technology, 2016, 57: 289-301.2 Kundu P, BlacherE, Elinav E, et al. Our Gut Microbiome: The Evolving Inner Self. Cell, 2017,171: 1481-93.3 Kelly J R, ClarkeG, Cryan J F, et al. Brain-Gut-Microbiota Axis: Challenges for Translation inPsychiatry. Annals of epidemiology, 2016, 26: 366-72.4 Scott L V, ClarkeG, Dinan T G. The Brain-Gut Axis: A Target for Treating Stress-Related Disorders.2013, 28: 90-9.5 Sarkar A, Lehto SM, Harty S, et al. Psychobiotics and the Manipulation of Bacteria-Gut-BrainSignals. Trends in neurosciences, 2016, 39: 763-81.6 Cryan J F, DinanT G. Mind-Altering Microorganisms: The Impact of the Gut Microbiota on Brainand Behaviour. Nature reviews Neuroscience, 2012, 13: 701-12.7 Dinan T G,Stanton C, Cryan J F. Psychobiotics: A Novel Class of Psychotropic. BiolPsychiatry, 2013, 74: 720-6.8 Smith K, Torres CD. Mental Health: A World of Depression. Nature 2014, 515: 181.9 Ledford H.Medical Research: If Depression Were Cancer. Nature 2014, 515: 182-4.10 Marije aan het R,Mathew S J, Charney D S. Neurobiological Mechanisms in Major DepressiveDisorder. Canadian Medical Association journal, 2009, 180: 305-13.11 Yu M, Jia H, ZhouC, et al. Variations in Gut Microbiota and Fecal Metabolic Phenotype Associatedwith Depression by 16s Rrna Gene Sequencing and Lc/Ms-Based Metabolomics. JPharm Biomed Anal, 2017, 138: 231-9.12 Naseribafrouei A,Hestad K, Avershina E, et al. Correlation between the Human Fecal Microbiotaand Depression. Neurogastroenterol Motil, 2014, 26: 1155-62.13 Jiang H, Ling Z,Zhang Y, et al. Altered Fecal Microbiota Composition in Patients with MajorDepressive Disorder. Brain Behav Immun, 2015, 48: 186-94.14 Zheng P, Zeng B,Zhou C, et al. Gut Microbiome Remodeling Induces Depressive-Like Behaviorsthrough a Pathway Mediated by the Host’s Metabolism. Molecular Psychiatry,2016, 21: 786-96.15 Kelly J R, Borre Y,C O B, et al. Transferring the Blues: Depression-Associated Gut MicrobiotaInduces Neurobehavioural Changes in the Rat. J Psychiatr Res, 2016, 82:109-18.16 Wallace C J K,Milev R. The Effects of Probiotics on Depressive Symptoms in Humans: ASystematic Review. Annals of general psychiatry, 2017, 16: 14.17 Pirbaglou M, KatzJ, de Souza R J, et al. Probiotic Supplementation Can Positively Affect Anxietyand Depressive Symptoms: A Systematic Review of Randomized Controlled Trials.Nutrition research, 2016, 36: 889-98.18 Liang S, Wang T, HuX, et al. Administration of Lactobacillus Helveticus Ns8 Improves Behavioral,Cognitive, and Biochemical Aberrations Caused by Chronic Restraint Stress.Neuroscience, 2015, 310: 561-77.