The belief that the mind plays an important role in physical illness goes back to the earliest days of medicine. From the time of the ancient Greeks to the beginning of the 20th century，it was generally accepted by both physician and patient that the mind can affect the course of illness，and it seemed natural to apply this concept in medical treatments of disease. After the discovery of antibiotics，a new assumption arose that treatment of infectious or inflammatory disease requires only the elimination of the foreign organism or agent that triggers the illness. In the rush to discover antibiotics and drugs that cure specific infections and diseases，the fact that the body's own responses can influence susceptibility to disease and its course was largely ignored by medical researchers.

心智在身体疾病中起重要作用的观念可以追溯到医学最早的时代。从古希腊时期到20世纪初，医生和病人普遍接受心智可以影响疾病进程的观点，并将其应用于疾病治疗的医学概念中似乎是自然而然的事情。抗生素被发现后，人们产生了一种新的假设，即治疗感染性或炎症性疾病只需要消除引发疾病的外部病原体或媒介。在急于发现能治愈特定感染和疾病的抗生素和药物的过程中，医学研究人员在很大程度上忽视了人体自身的反应能够影响对疾病的易感性及其进程这一事实。

It is ironic that research into infectious and inflammatory disease first led 20th⁃century medicine to reject the idea that the mind influences physical illness，and now research in the same field — including the work of our laboratories and of our collaborators at the National Institutes of Health — is proving the contrary. New molecular and pharmacological tools have made it possible for us to identify the intricate network that exists between the immune system and the brain，a network that allows the two systems to signal each other continuously and rapidly. Chemicals produced by immune cells signal the brain，and the brain in turn sends chemical signals to restrain the immune system. These same chemical signals also affect behavior and the response to stress. Disruption of this communication network in any way， whether inherited or through drugs，toxic substances or surgery ，exacerbates the diseases that these systems guard against： infectious，inflammatory，autoimmune，and associated mood disorders.

具有讽刺意味的是，对感染性疾病和炎症性疾病的研究最初导致20世纪的医学界拒绝接受心智影响身体疾病的观念，而现在同一领域的研究——包括我们实验室的工作以及我们在国家卫生研究院的合作者的工作——正在证明相反的情况。新的分子和药理学工具使我们能够识别出免疫系统和大脑之间存在的复杂网络，这个网络使这两个系统能够持续而迅速地相互传递信号。免疫细胞产生的化学物质向大脑发出信号，大脑反过来向免疫系统发送化学信号以抑制它。这些相同的化学信号也会影响行为和对应激的反应。以任何方式（无论是通过遗传、药物、有毒物质还是手术）破坏这一通讯网络，都会加剧这些系统所防御的疾病：感染性、炎症性、自身免疫性和相关情绪障碍。

The clinical significance of these findings is likely to prove profound. They hold the promise of extending the range of therapeutic treatments available for various disorders，as drugs previously known to work primarily for nervous system problems are shown to be effective against immune maladies，and vice versa. They also help to substantiate the popularly held impression（ still discounted in some medical circles）that our state of mind can influence how well we resist or recover from infectious or inflammatory diseases.

这些研究成果的临床意义可能非常深远。这些发现预示着各种疾病的治疗范围将得到扩展，因为先前已知主要用于神经系统问题的药物已被证明对免疫疾病也有效，反之亦然。它们也有助于证实人们普遍持有的印象（尽管在一些医学界仍被否定），即我们的精神状态可以影响我们抵抗或恢复传染性疾病或炎症性疾病的能力。

The brain's stress response system is activated in threatening situations. The immune system responds automatically to pathogens and foreign molecules. These two response systems are the body's principal means for maintaining an internal steady state called homeostasis. A substantial proportion of human cellular machinery is dedicated to maintaining it.

大脑的压力反应系统在威胁性情况下会被激活。免疫系统会自动应对病原体和外来分子。这两个反应系统是身体维持内部稳态的主要手段，这种稳态被称为内环境稳定。人类细胞机制中有相当一部分是专门用来维持这种稳态的。

当稳态受到干扰或威胁时，一系列分子、细胞和行为反应就会发挥作用。这些反应试图对抗干扰因素，以便重新建立稳态。它们可以针对外来入侵者或特定的压力，也可以在稳态受到的威胁超过某一阈值时变得普遍和非特异性。适应性反应本身也可能变成产生疾病的压力源。我们刚刚开始了解大脑和免疫系统之间的相互依赖关系，以及它们如何相互调节和反调节，以及它们自身如何出现故障并产生疾病。