From Children's Health Defense (formerly World Mercury Project.)
A common criticism of the Western medical model is that it tends to look at body systems in isolation from one another. Here and there, however, scientific disciplines arise that explicitly acknowledge interactions across systems. Neuroimmunology is one such field, having established that the central nervous system (CNS) and the immune system engage in bidirectional communication and that proper brain function depends on a well-regulated immune system.
As neuroimmunologists have come to accept that “components of the immune system play previously unrecognized roles in the nervous system,” the field has contributed substantially to the understanding of neurodevelopmental disorders and particularly autism spectrum disorders (ASDs). Neuroimmunology’s insights about ASD have been sorely needed because, on the surface, autism remains a subjectively defined “mental health” diagnosis (at least according to the Diagnostic and Statistical Manual of Mental Disorders), characterized by “dysfunction in social behavior and language, abnormal response to sensory input, and…repetitive behavior and cognitive disabilities.” As autism research has grown in sophistication—increasingly highlighting ASD’s underlying biological basis—it has become apparent that immune dysregulation is just as much of a hallmark of autism as brain inflammation is. What is more, the wrong kind of immune influences during pivotal stages of early brain development can have profound effects on both neural and immune function later in life.
ASD and other neurodevelopmental disorders perfectly illustrate the situation of immune-inflammatory mechanisms gone awry.
Skewed immune response
Under ordinary circumstances, the immune system mobilizes inflammatory molecules in response to infection or tissue damage; once the job is done, the inflammatory response subsides. However, a delicate balance exists between the appropriate activation needed for “beneficial immune maintenance” and the “deleterious over-activation of immune cells” that can lead to systemic dysfunction. ASD and other neurodevelopmental disorders perfectly illustrate the situation of immune-inflammatory mechanisms gone awry.
A 2015 review outlined this “pro-inflammatory skew” in ASD, noting that autism is characterized, in part, by “hyperexcitable” and “exaggerated” responses from T cells—the all-important immune cells that attack foreign substances, augment the action of antibody-producing B cells and produce molecular messengers called cytokines. Autism researchers have noted the complex roles played by cytokines in neurodevelopment and have repeatedly observed elevated levels of some cytokines in individuals with ASD—including interleukin-4 (IL-4), interleukin-6 (IL-6), some types of tumor necrosis factor (TNF) and others. Elevated IL-4 in neonates has been associated with increased odds of severe ASD later in childhood. These “excessive and skewed cytokine responses” typify the ASD immune profile to such an extent that researchers have proposed using cytokine evaluation as a biological marker for ASD. According to the authors of the 2015 review, skewed immune-inflammatory mechanisms are not just associated with ASD but likely play a fundamental role in autism causation. Read more here.