The CHAT test (Checklist for Autism in Toddlers) is an excellent tool for both Parents and Health Professionals to use in diagnosing Autism in toddlers and has been found to be invaluable in doing so.
What Causes Autism?
Nobody knows for sure. Children with Autism are described as being on "The Spectrum" (Autism Spectrum Disorders). This refers to how Autism and other conditions are viewed as being related in symptoms but with varying degrees and shades of severity. There are other conditions like Asperger's Syndrome, Pervasive Development Disorder (PDD), Fragile X Syndrome, Attention Deficit Hyperactivity Disorder (ADHD), etc.- that exhibit similar symptoms in some cases.
There is research to suggest that in some cases there is a genetic component that is triggered that leads to Autism. There is also research that indicates that Autism is due to environmental influences such as vaccinations. In the future, it may be found that both reasons (and others) are true for different children; and then, we will finally be able to answer the question, "What is Autism?"