In our imaging study, we are measuring a number of different aspects of brain function and brain structure in parents of children with autism. We are also examining high functioning (HF) adults with autism. Up until now, it has not been possible to examine brain function or brain structure in live humans.

Genetic factors are important in autism: therefore, investigating relatives of children with autism has potential for identifying sub-clinical biological factors that may be influenced by these genes. Serotonin (5HT) function and brain structure are 2 examples of the biological factors that may be influenced by an underlying genetic mechanism.

Serotonin is a chemical messenger in the brain that is thought to have an important role in autism. This is based on previous studies that have shown abnormal serotonin function in autistic children and their relatives. Unfortunately, these studies have not examined serotonin function in the brain: instead, they have examined serotonin function in the blood of these individuals.

With the advances in modern imaging, we are now able to examine brain 5HT function in live humans. 18F Setoperone Positron Emission Tomography (PET) is an imaging method capable of measuring brain 5HT function in live humans. Magnetic Resonance Imaging (MRI) is an imaging method used for examining brain structure in live humans.

In our imaging study, provisional analysis of the PET data shows that brain serotonin receptor density is diminished in 14 of 19 regions sampled in our parent group. This is in agreement with our prediction that serotonin function is diminished in autism. We have not yet imaged any high functioning adults with autism, but plan to start this phase of the study towards the end of the year. In addition, we need to complete the MRI examinations, which will provide us valuable information on structure of the brain in these individuals.

Unfortunately, a limitation with our findings is that our parent and control groups are not perfectly matched for age. This means that we need to image a few more parents and control subjects before drawing any definitive conclusions from our findings.