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Autism: Did the word make you think of mitochondria?

by: Christine Younan

For the past number of years, autism has been known to the general public as some vague disease of the brain, constituting various symptoms including abnormal social interaction, inappropriate communication, and the presence of stereotyped behaviors.1 This disease presents itself in a way that deems its origins worthy of some grand, subtle mismatched neural networks in the brain; however, it is only more recently that pediatric neurologists are looking beyond this seemingly too obvious origin of dysfunction to a more miniscule, mundane organelle: the mitochondrion. The mitochondrion provides a large alleyway for researchers of autism to begin their quest in seeking out the potential correlation autistic patients have with specific abnormalities in the mitochondria, an organelle present in numbers reaching the hundreds in nearly every cell of the body.

The mitochondrion: I remember that having some sort of significance in general biology. Let’s refresh. The mitochondrion is ultimately the cell’s powerhouse, producing vast quantities of adenosine triphosphate or ATP. In doing so, the mitochondria of the body break down carbohydrates and fats through a series of enzyme cascades and an electron transport chain. Because of the mitochondria’s significant presence in the body and the necessary metabolic processes it performs, the consequences of defects in this precious organelle already seem remotely dreary. When the mitochondria are deficient in their performance, “final end products from several metabolic systems may build up, causing in the metabolic systems themselves to shut down”.1 Additionally, the mitochondria play a role in signaling the cell to apoptose (analogous to suicide). When the mitochondria becomes defected, it can signal the cells to prematurely begin apoptosis, which leads to invariably unhealthy effects on the tissue in the vicinity, and ultimately on the organism as a whole.1 A defect in the mitochondrion can also “create reactive oxygen species that can be damaging to neighboring healthy tissues, as well as to individual cell function”.1 Ultimately, the effects appear quite challenging for cells with such idiosyncratic mitochondrion, but how do these effects interact to produce the symptoms of autism?

Because the mitochondria are primarily involved in production of cellular energy, the overall effect of the ill-suited mitochondria takes effect on the organs of the body that undergo ATP intensive processes. These processes include those of thinking, digesting, fighting off the latest strand of flu, and in short, many seemingly basic actions that require plethora of energy and complexity underlying their effectiveness. Therefore, a child with mitochondrial disorder may exhibit “developmental delay, loss of developmental milestones (i.e., regression), seizures, muscle weakness, gastrointestinal abnormalities, and immune dysfunction”.1 The overall presentation of these symptoms strongly resembles many of the multi-symptom effects of autism. Without even specific tests, the evident correlation of these two disorders makes it very probable that a child with autism may have mitochondrial disorder.

The actual diagnosis of mitochondrial disorder involves a series of blood tests and urine sampling that are often unrealized by the lack of information. However, one significant marker of mitochondrial disorder manifested in autistic children is the elevated levels of lactic acid. The mitochondrion cannot break down the pyruvate in the cell, and so the pyruvate then is left with no other choice than to decompose into lactic acid. A study on the relationship between elevated levels of lactic acid, as well as other traditional markers, associated to mitochondrial disease with autism were performed in Portugal; children believed to have autism underwent a muscle biopsy and nearly 7% were found to have confirmed mitochondrial disease.1 This remarkable study is one of the beginnings of an increasingly founded belief that a subset of autistic children may have mitochondrial dysfunction been overlooked.

Additionally, the connection of mitochondrial disease and autism can be vividly observed in the form of treatment applicable in both cases. Although medical treatments have truly improved, an exact remedy to mitochondrial disorder has not been prescribed. Certain vitamin supplements and diet adjustments, such as coenzyme Q10 (idebenone), are the essence of the treatment of this disease. The specific nuances in the prescription of treatments are “based upon rational biochemistry and knowledge of what vitamins/ cofactors may supplement the defective enzyme machinery or which diet may provide the best fuels for the specific disorder”.1 Such a treatment is analogous to the diet adjustments delineated for children diagnosed with autism.

Clearly, autism and mitochondrial disease contain a series of parallel symptoms, diagnoses, and treatments that maintain the idea that mitochondrial disease may be the precipitating factor of autism in many children. The mitochondria, with its vast sequence of enzyme cascades and energy formation and supply through ATP, provides a substantial means by which researchers of autism may begin to pin down specifics in what causes the symptoms of a disease which affects a significant proportion of young children today. Much work has yet to be done in this relatively novel field, but no doubt, an overwhelming amount of potential will be founded in the inner-workings of the mitochondria in curing autism.


1. Frye, R.; Poling, J. Mitochondrial Disorders and Autism. Biomedical, 2009.

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