Next now tonight we -- to a startling new medical report about autism new numbers from the CDC showing one child in 68. Has autism. A 29%. Increase from two years ago and ABC's chief medical editor... See More
Next now tonight we -- to a startling new medical report about autism new numbers from the CDC showing one child in 68. Has autism. A 29%. Increase from two years ago and ABC's chief medical editor doctor Richard -- -- on what is driving those numbers. Am thanks. This is twelve year old left a little boy with a love of trains have you always like trans. I felt like Thelma it's -- -- Just one child behind today's startling new numbers just two years ago one in 88 American children were on the autism spectrum. Today that new number one in 68. Boy still almost five times more likely to be diagnosed than girls and why this surge it could be better diagnosis. But experts -- say there are more children with autism. What's causing it. We know genetics play a role -- that young autistic brains are physically different but it's still a puzzle. Today's report finds most children -- being diagnosed after each for doctors just aren't screening. But there are new technologies to catch it sooner -- I tracking. Children with autism -- to CPC's differently in six month old babies hits -- like this could be a warning sign. And and new approaches to treatment to. For let -- about using the trains he looked. New York's transit museum running a special program for enthusiasts with autism taking their love of trains and teaching them how to make friends. Rather than trying to. Get rid of their obsession we're saying let's put you in -- place and working with the topic that you love how do you feel about -- Happy tonight as those numbers are growing so was the race to find out why. Doctor Richard -- ABC news New York.
This transcript has been automatically generated and may not be 100% accurate.