Autism spectrum disorders (ASD) are complex developmental conditions characterized by restrictive repetitive behaviors deficits in communication and social interaction as well as sensory perception disturbances. While no specific etiology has been directly linked to autism researchers do agree that a variety of influences including genetic factors are known to be involved. Research has also shown that environmental elements such as diet toxin exposure and vaccinations play a crucial role. One in 88 children in the US is thought to be affected by autism and it related conditions. 

Abnormal inappropriate or a dysregulated immune response especially during pregnancy has also been associated as a possible cause of autism and is the focus of this particular blog.

In the neonate the blood brain barrier (BBB) is much more developed and thereby more protective than that of the fetus limiting the entry of immune elements such as lymphocytes macrophages various cytokines and antibodies into the brain. However the BBB is very permeable during fetal development and can be compromised by infections and environmental exposures throughout gestation. The absence of a complete barrier allows immune components access to the brain. Individuals with autism show increased inflammatory cytokines in the brain as well as antibodies  particularly those generated from the mother - that target brain tissues. This relationship between a possible dysregulated immunological response and or perhaps a not altogether fully developed and protective BBB may interfere with normal brain development and function potentially contributing to the development and/or symptoms of ASD.

For instance in this study researchers found that women with a particular subset of antibodies in their bloodstream are at greater risk of having a child with autism and that their children exhibited more severe language delays irritability and self-injurious behaviors than did the autistic children of mothers whose blood did not have the antibodies. In another study levels of chemokines where found to be unusually high in those children displaying autistic types of behaviors again suggesting aberrations in the immunological response can indeed increase the risk of developing autism in genetically vulnerable children.

Viral activation of the mother's immune system during pregnancy can also increase the risk of having a child with autism. Major histocompatibility complex class I (MHCI) is a class of proteins responsible for intercellular communication of immune components that include leukocytes and other cells. Researchers found that the high MHCI levels typically found during viral induced infectious states impaired the ability of the neurons from newborn experimental mice's brains to form synapses suggesting that one origin of ASD may be caused by changes in the development of connections in the brain brought on by immunological stress produced in utero. Also over-activation of toll-like receptors again during viral infections can inhibit stem cell proliferation increasing the risk of neuropathology and developmental behavioral disorders.

In order to study these phenomena researchers are able to create autistic mice in the laboratory through the provocation of a viral infectious state in the mother while pregnant. In an interesting experiment the autistic offspring were subsequently treated with a bone marrow transplant in an attempt to correct the maternally generated immunological dysfunction. Remarkably the offspring mice once treated no longer displayed the autistic types of behaviors they previously demonstrated. This indicates that immune irregularities caused in utero can contribute to ASD-related behaviors in neonates.

In light of the above it's not unreasonable to suggest keeping mom's immunity functioning at optimal levels while pregnant. Unfortunately during these periods women are limited in what they can supplement but vitamins D and C zinc and the consumption of food/medicinal mushrooms like shiitake and maitake can help boost immunity helping to decrease the risk of experiencing a viral infection during an obviously vulnerable time.

Michael Fuhrman D.C.