Research & Education

From Epigenetics to the Microbiome in Autism

Early in July 2019, the University of North Carolina (UNC) School of Medicine announced a discovery, which can be added to the ongoing research efforts to better understand autism spectrum disorder (ASD), its beginnings, causes, and solutions. Namely, a genetic polymorphism has been identified that may be linked to disruptions in neuronal differentiation and connectivity early in life, triggering the development of ASD.

Without question, the growing prevalence of autism has struck alarm in both laypersons and practitioners. In just 15 years, the prevalence has almost tripled since the CDC started tracking it in 2000 through the Autism and Developmental Disabilities Monitoring (ADDM) Network. The ADDM Network first reported an estimated 1 in 150 children of all ethnicities within the United States were diagnosed with ASD. However, by 2014 this rate increased to 1 in every 59 children. Increased awareness and improved diagnostic standards have certainly contributed to this rise, but unprecedented ASD trends which cannot be simply explained by “better science” are also emerging and cry for greater research efforts that can provide answers.

In light of this situation, the discovery made by UNC lays down yet another piece of the ASD puzzle. Memo1 is a protein required to organize a carefully constructed scaffold-like structure by radial glial cells (RGCs) in the cerebral cortex – the area responsible for perception, speech, long-term memory, and consciousness. RGCs are a type of neural stem/progenitor cells which divide and give rise to cortical neurons. RGCs carry out their function by first forming the scaffold-like structure from the base of the cortex to the top. Newly emerging cortical neurons then scale this structure and form the organized layers of neurons necessary for optimal cortex function.

When the gene which encodes for Memo1 is mutated, the scaffold-like structure built by RGCs is disorganized, meaning the layers of neurons cannot be formed, compromising the function of the cortex. This situation has been linked to ASD and UNC confirmed that individuals with ASD are more likely to possess mutations of the Memo1 gene.

There is certainly no affirmative cause for gene polymorphisms; however, we know that certain biological activities can help preserve the integrity of the genetic code from one generation to another. One such activity is antioxidant capacity and function. Recent research also makes a close association between deficient antioxidant production, subsequent oxidative stress, and ASD.

Oxidative stress is not an independent risk factor, though. It often travels with inflammation as its companion and like oxidative stress, inflammation is another common denominator in ASD. Both oxidative stress and inflammation are outcomes of the standard Western diet and lifestyle which is abundant in added sugars, chemical-based food additives, and genetically modified foods, low in fiber and antioxidant-rich fruits and vegetables, and markedly void of adequate physical activity. When you include the environmental insults such as air and water pollution from industrial processes, increased pharmaceutical use, and electromagnetic radiation, it is a wonder the body maintains its resiliency at all.   

Both oxidative stress and inflammation are rooted in the microbiome of the gut and not surprisingly, researchers are also making a strong connection between ASD and disruption of the microbiome. Therefore, when considering the impact of oxidative stress and inflammation on the integrity of the genome, it is logical to begin by evaluating the health of the microbiome. A review published in 2018 in Frontiers in Cellular Neuroscience pointed to dysbiosis and early disruption of the microbiome as being a leading cause for decreased antioxidant capacity and resulting epigenetic changes that are commonly found in ASD. The review also cites evidence that suggests that short-chain fatty acids such as butyrate, produced by a healthy microbiome, act as epigenetic switches that can turn genes on and off and alter both antioxidant and immune responses.

While it is exciting to discover more pieces of the puzzle of ASD and epigenetics is an equally advancing area of research, let’s not lose sight of the foundational systems that have the power to influence many of these outlying elements that contribute to the development of conditions such as ASD.