No one knows exactly what causes autism, why some children have it and others don't. What we do know is that parents need to be able to recognize the early signs.

Pictures of Drew Dabney reveal a physically healthy little boy but Drew began to exhibit some disturbing behavior around his first birthday.

His mother, Kim Dabney says, "He started to cry all the time, had chronic ear infections, diarrhea, stop pointing. Babies do, 'what's that, what's that?' He stopped doing that."

Kim Dabney had his hearing tested but Drew wasn't deaf. He was diagnosed as autistic.

Autism Spectrum Disorders cover a range of developmental disabilities from mild to severe.

Children typically show some signs by the time they're 18-months-old.

Dr. Myra Preston is a neurophysiologist who says, "The classic early warning signs would be inability to sleep through the night, a baby that appears very fussy and perhaps is misdiagnosed as being colicky, a baby that cannot be satisfied by holding and nurturing and cooing."

A diagnosis of autism usually comes between the ages of two and three. Language is a key indicator.

Dr. Preston says, "Once the child reaches the stage where they should be acquiring language, you will see that they either do not speak or they speak a language of their own design."

Most specialists agree that a child should be evaluated immediately if he or she: