Why do you suspect autism? 4 months is NOT too young to diagnosis a child with autism. There are two forms: infantile autism, less than 20% of all cases of autism, and regressive autism. Infantile autism presents at birth while in regressive autism the child develops normally until the age of two and then loses skills that were learned or stops developing relative to peers. If you have a suspicion, see a developmental specialist. I had a suspicion & asked my pediatrician who said that my child was colicky. Two years later we received the official autism diagnosis. My son is high-functioning and will likely test off the spectrum one day. He has received great early intervention services. Because of his cognitive abilities, however, I think doctors were even less likely to see any "problems." Furthermore, because one of the key components to autism is social interaction, it is difficult to gauge at an early age. Great infant studies currently are coming out of Yale & UCLA. From my own experience, in hindsight, my son presented symtoms from birth. He did not want to be held; he was ultra sensitive to changes in temperature, light, touch, and sound; and he would only pacify when starring at a ceiling fan or the reflection of the spinning stroller wheels in the oven glass. If you would like any references or discuss the symptoms that worry you, I would be happy to talk more with you. Take care.