Autism Spectrum Disorder (ASD) is a disease that affects about 1 in 68 children in the United States, according to an ADDM Network Survey from 2012. ASD includes disorders like Asperger’s, Autism, Pervasive Developmental Disorder, and Childhood Disintegrative Disorder, that all have slightly different levels of cognitive and learning impairment, variations in behaviors, and other symptoms. There are two main types of behaviors in children with ASD, although not all people will display all the symptoms, and some may exhibit several of them. The first is restrictive or repetitive behaviors, the second is social communication/interaction behaviors. Sometimes diagnosis can be tough because it is difficult to discern, for example, if a child falls in the lower-functioning end of Asperger’s, or the higher-functioning end of Autism, as they fall on a spectrum. Even with some of the impairments that these children have, they often have great strengths and abilities in one subject or aspect of their lives, such as math, music, or other things.
The prevalence of ASD in the United States is increasing. Some argue that this could be due just to higher numbers of diagnoses as awareness has risen. There is no specific cause that has been identified for ASD, but there are genetic factors that are thought to be responsible for ASD occurrence, although they are not able to account for all cases. There appears to be some environmental factors that also contribute to the number of cases of ASD or increase the risk for it, especially if some of those autism-related genes are present.
The article that we read in class identified two main environmental factors that are thought to contribute to cases of ASD – zinc deficiency and dysfunctional immune system. It is thought that they contribute to dysfunctional excitatory signaling as they inhibit correct structure and development of synapses and their receptors and cause some dysfunctional kinase signaling. Many of the genes implicated in ASD either need zinc or are involved in zinc homeostasis in the body. Low levels of maternal zinc in pregnancy can cause immune system dysfunction, which can make the fetus more susceptible to infections while in utero. This can in turn cause some developmental problems in the child and their brain.
As mentioned, zinc deficiency contributes to immune system abnormalities. Obviously this can make the child more susceptible to diseases, but inflammation can have detrimental effects on the body when it goes on for too long. It can damage developing cells and contributes to neural plasticity at synapses.
These two main environmental factors affect each other, but they are in interplay with other environmental and genetic factors as well. Things such as prenatal and perinatal stress, parental age, exposure to toxins, prenatal infections, and melatonin deficiency can all contribute to immune system abnormalities. Malnutrition, copper overload, and melatonin deficiency contribute to zinc deficiency.
Mutations in genes can affect zinc homeostasis as well, and increased age of the parents gives a higher chance for mutations. Exposure to toxins and zinc deficiency also may cause genetic mutations, and when they are in those genes that encode for scaffolding proteins, receptor proteins, or signaling cascade proteins, it does not allow for proper synapse function, contributing to the expression of ASD.
Thus, it is hard to pin-point the exact cause of ASD, but it is obvious that there is important environmental contributors along with the genetic components of the disease. It will be important to educate parents about proper nutrition so they get the nutrients they need, such as zinc, to help the baby develop properly and protect against maternal and fetal infections. It will also be important to be aware of the possible effects that exposure to toxins or other environmental agents may have on the body as well. As more is learned about zinc, the immune system, environmental contributors, and their interactions with autism-implicated genes, maybe someday we will be able to prevent or even cure people with ASD.
Zinc and the Immune System: The Secrets of Autism Spectrum Disorder?
