|Brendan McLean, NAMI communications intern|
Mitochondria: Differences on a Cellular Level
Many mental illnesses have had their magic cure or culprit, with autism being no exception—childhood vaccines have gotten a great deal of publicity as a possible cause of the disorder.With the connection between vaccinations and autism discredited, or shown to be extremely isolated, it was necessary for researchers to begin searching in another direction for the cause of autism. This past month a new study released in the Journal of the American Medical Association by Dr. Cecilia Giulivi from the University of California, Davis, showed promise in helping identify at least one cause of autism: differences in mitochondria.
Mitochondria, the cell’s powerpacks, disassemble sugar molecules and turn the newly released energy into a form that the body can use. Defects in the mitochondria may explain the onset and severity of autism in some children. Mitochondrial dysfunction has already been shown to play a role in the development of other neurological conditions, such as Parkinson’s, Alzheimer’s diseases, schizophrenia and bipolar disorder. Dr. Giulivi found that the mitochondria in children with severe autism, compared to a control group of children than did not have autism, consumed far less oxygen , a sign of lower cell activity and leaked damaging oxygen-rich chemicals such as hydrogen peroxide, which exists at levels twice the norm because is not cleaned up by enzymes as it would in normal cells.
Genetic Similarities and Beyond
The sample size for this study was extremely small— only 10 children with severe autism. It is also not certain precisely when or why the mitochondria dysfunction starts, whether in the womb or later on in infancy, or related to genetic factors or environmental factors. These questions have also dogged mental illness research, with scientists now theorizing that schizophrenia is the result of the interaction between several possible genetic and environmental factors.
A recent comparison of the genetics behind autism and schizophrenia found that while some of the genetic differences for the two conditions might occur in the same sites, in one disorder certain proteins are overproduced while in the other the opposite is true. The more we learn about conditions like autism, schizophrenia and other mental illnesses like bipolar disorder, the more we realize that the distinctions between them are not always clear.
Autism has recently been re-categorized as a spectrum disorder, giving rise to the idea of multiple autisms rather than one. Similarly, there is currently a movement within the research community to reclassify schizophrenia as a syndrome in order to allow for a greater variation among people living with the condition, some of whom might share characteristics with other conditions like depression or bipolar disorder.
It is important to note that similarities do not only exist between people living with autism, schizophrenia or any mental illness—on a genetic level we are all more alike than different, with 99.9 percent of DNA the same in every person. As our understanding of the genetic basis of conditions like autism expands, we may find that the one-tenth of a percent that is genetically different in all of us has some unsuspected similarities, allowing us to discover knowledge that helps develop treatments for other mental illnesses.