Autism and autism spectrum disorder are both general terms for a group of complex disorders of brain development. These disorders are characterized by difficulties in verbal and nonverbal communication, social interaction, and repetitive behaviors. Autism begins during early brain development, but symptoms and signs usually cannot be seen until the child is two or three. About 1 and 88 children in the U.S. will develop some form of autism and it is about five times more common in boys than girls. Studies show that 1 in 252 girls and 1 in 54 boys in the U.S. are diagnosed with autism.
What causes autism? Not long ago, the answer to this question would have been â??we have no idea.â?? Researchers are now delivering the answers. First, we now know that there is no one cause of autism. Over the last five years, researchers have found a number of rare gene changes, or mutations, associated with autism. However, most cases of autism appear to be caused by a combination of autism risk genes and environmental factors that influence early brain development.
Between ages three and ten, autistic children exhibit distinct brain chemical changes that differ them from children with developmental delays and those with typical development, according to a study at the University of Washington. â??In autism, we found a pattern of early chemical alterations at the cellular level that over time resolved â?? a pattern similar to what others have seen with people who have had a closed head injury and then got better,â?? Dr. Stephen R. Dager was quoted as saying. â??The brain developmental abnormalities we observed in the children with autism are dynamic, not static. These early chemical alterations may hold clues as to specific processes at play in the disorder and, even more exciting, these changes may hold clues to reversing these processes.â?? In the study, researchers compared brain chemistry among three groups of children: those with autism spectrum disorder, those with a diagnosis of developmental delay, and those considered typically developing. They used MRI to measure tissue-based chemicals in three age groups: three to four years old, six to seven years, and nine to ten years. An important finding concerned changes in gray matter N-acetylaspartate concentration in scans of the three to four year-olds, concentrations were low in both the autism spectrum disorder and developmentally delayed groups. By nine to ten years, N-acetylaspartate levels in the children with autism spectrum disorder had caught up to the levels of the typically developing group, while low levels of N-acetylaspartate persisted in the developmentally delayed group.