Autism starts affecting babies' brains as early as 4 months old

Autism takes a heavy toll on families — autistic teens are more likely to be bullied, and families with autistic kids are likelier to have lower incomes. But now at last, we're starting to learn more about what causes autism.

The International Meeting for Autism Research is taking place right now in San Diego, and already a lot of great data about the reasons for autism has been presented. The bottom line: Autism is a multi-factoral disorder — even with in each individual child, Irva Hertz-Picciotto told a press conference yesterday. But we're starting to understand some of the factors that come into it.

And one crucial bit of information from yesterday's press conference: David Amaral of U.C. Davis says that changes in brain growth associated with regressive autism are observable as early as 4-6 months of age, long before any behavior changes show up. "Precocious" brain growth and larger head diameters in those early months are associated with regression. (Which means, among other things, that the MMR vaccine, which is administered at 12 months, can't possibly be causing these cases.)

Researchers have been able to identify autistic children at younger and younger ages, thanks to new diagnostic guidelines, and one result is a huge MRI study of autistic children aged 12 to 40 months. Among other things, researcher Eric Courchesne found that connectivity between the temporal lobe and the limbic system (including the amygdala) is very different in austistics, from early on. And young autistics have twice the number of cells in their frontal cortex as other kids. Also, a measure of brain development called fractional anisotropy (FA) is much higher in young autistics than other kids, but then doesn't grow as quickly as it does in normal children as they grow older.

(There's some great live-blogging of the conference going on at LeftBrainRightBrain and The Thinking Person's Guide to Autism.)

Other research presented today suggested that a difficult labor or fever during the early part of pregnancy could help cause autism-spectrum disorder (ASD), and that mothers who have hypertension or diabetes, or are obese before pregnancy, may be more likely to have autistic children.

The bottom line, though, is that we're only just starting to learn the truth about autism and what causes it. And we've been held back from making progress for too long, thanks to myths like the vaccination myth and before that, the "refrigerator mother" myth. [Thanks Shannon!]