Children with autism have mitochondrial dysfunction

Children with autism are far more likely to have deficits in their ability to produce cellular energy than are typically developing children, a new study by researchers at UC Davis has found. The study, published in the Journal of the American Medical Association (JAMA), found that cumulative damage and oxidative stress in mitochondria, the cell's energy producer, could influence both the onset and severity of autism, suggesting a strong link between autism and mitochondrial defects.

After the heart, the brain is the most voracious consumer of energy in the body. The authors propose that deficiencies in the ability to fuel brain neurons might lead to some of the cognitive impairments associated with autism. Mitochondria are the primary source of energy production in cells and carry their own set of genetic instructions, mitochondrial DNA (mtDNA), to carry out aerobic respiration. Dysfunction in mitochondria already is associated with a number of other neurological conditions, including Parkinson's disease, Alzheimer's disease, schizophrenia and bipolar disorder.

The researchers obtained blood samples from each child and analyzed the metabolic pathways of mitochondria in immune cells called lymphocytes. Previous studies sampled mitochondria obtained from muscle, but the mitochondrial dysfunction sometimes is not expressed in muscle. Muscle cells can generate much of their energy through anaerobic glycolysis, which does not involve mitochondria. By contrast, lymphocytes, and to a greater extent brain neurons, rely more heavily on the aerobic respiration conducted by mitochondria. The researchers found that mitochondria from children with autism consumed far less oxygen (66 percent) than mitochondria from the group of control children, a sign of lowered mitochondrial activity. For example, the oxygen consumption of one critical mitochondrial enzyme complex, NADH oxidase, in autistic children was only a third of that found in control children. Reduced mitochondrial enzyme function proved widespread among the autistic children.

Mitochondria also are the main intracellular source of oxygen free radicals. Free radicals are very reactive species that can harm cellular structures, including DNA. Cells are able to repair typical levels of such oxidative damage. Giulivi and her colleagues found that hydrogen peroxide levels in autistic children were twice as high as in normal children. As a result, the cells of children with autism were exposed to higher oxidative stress.If researchers find some kind of blood marker that is consistent with and unique to children with autism, it changes the way we diagnose this difficult-to-assess condition. The real challenge now is to try and understand the role of mitochondrial dysfunction in children with autism.

Bonnie - what is the most significant nutrient we know of that supports mitochondria? Co-Enzyme Q10