Tuesday, July 26, 2011

Clinic Notes: The Genetics of Autism

Most of us who have been treating autism for a long time have accepted that autism is a genetic disorder. When parents, who have a child with autism, inquire about having another child, we often recite the concordance rates for them. In other words, what are the odds of having another child with autism? But I have always wondered if autism is a genetic disorder, why the sudden rise that is now epidemic. What changed all of a sudden genetically to cause the epidemic? It is unlikely that people with the autism gene(s) started mating together all at once. Something more than genetics have to be involved to account for the dramatic in autism.
In a recent study, the genetics of autism has been turned upside down. Twins were identified in the California Department of Developmental Services database who had an autism diagnosis. Of these 192 pairs of twins, which had at least one twin diagnosed with autism, the study found a concordance rate of 77% for identical twins and 31 % for fraternal. These figures are in similar to previous studies. But when these results were analyzed by a computer model that looked at the role of genetic and environmental factors the story changed. Now genes accounted for 38% of the risk factors and environmental 58%. Of course the study has been criticized.

Friday, July 15, 2011

Clinic Notes: A Biological Marker for Autism?

One big problem in conducting studies on the causes of autism is reliable diagnosis. There are no biological markers of autism so autism is inferred from the child's behavior. The problem arises then that there such obvious variably from one child with autism to another that a "spectrum" is required to "explain" this variability. So is autism one disorder or many? Obviously, this is a fundamental question that must be answered before much progress can be made in discovering the cause of autism and developing more effective therapies. A study at the University of California at San Diego found differences in functional magnetic resonance image (fMRI) scans of children diagnosed behaviorally with autism and normal controls. The fMRI's, taken while the children were sleeping, found that the two hemispheres of the brains of the children with autism were not "syncing."
Well, if this is replicated in other studies it will certainly advance our understanding. The only downside I see is that research will then be done in large universities with large grants. The cost for a fMRI and a MRI suite can run $500,000.

Friday, July 08, 2011

Clinic Notes: Antidepressants and Autism

According to a California study, mothers who use selective serotonin reuptake inhibitors (SSRI's), a common medication for depression, during pregnancy have a higher rate of children with autism. The net effect of these drugs is to increase the amount of serotonin in neurons in the brain that use serotonin as their neural transmitter. There are studies that indicate that children with autism have higher levels of serotonin in their circulatory systems. Sounds good. But there are also studies that show that children with autism have lower levels of serotonin and often children with autism are given SSRI's to increase serotonin. Confused? Me too. Because I have seen children with autism in my clinic improve when they are given SSRI's. I do not know how to explain this. But I do know that in this study and others serotonin levels are measured peripherally in the blood usually. No one has demonstrated that peripheral measures of serotonin correspond to central levels in the brain. I am getting to the point that I want to see a study that finds something that doesn't cause autism.