Narrator: This is Science Today. For the first time, researchers have followed the brain-growth trajectories from infants to children who later develop autism. David Amaral, director of the University of California, Davis, MIND Institute says their study is also the first to associate excessive cerebrospinal fluid during infancy with autism.
Amaral: Cerebrospinal fluid is in everybody's brain. It's sort of a shock absorber; it allows the brain to not damage itself if the skull is hit. It's just not water, it's actually a system for carrying out toxic waste from the brain. It is also a system for carrying out what's called trophic factors that regulate how the brain develops.
Narrator: In their study, kids who went on to have autism not only had extra cerebrospinal fluid at 6 to 9 months of age, but it persisted at 18 to 24 months.
Amaral: So, it may be that while you would see this anomaly in many children, some of whom are not going to go on to have autism, that the persistence of it over time is going to be the real red flag.
Narrator: For Science Today, I'm Larissa Branin.