What causes autism?

RONALD LEAF: We simply don't know the cause of autism. There's been no research evidence that helps us know the cause. [MUSIC PLAYING]

It's a complex issue, because it's an environmental versus heredity kind of discussion, nature

versus nurture, something we've been debating in psychology forever. Same in autism. What's the cause?

Is it nature? Is it nurture? Is it environment? Is it heredity? They're linked together. It's impossible for you to pull those out

to know which is the true cause. Speculation is that it's a neurological disorder that

meets the right environmental conditions. That's probably the cause of autism, is that interaction between the two,

which really doesn't lead us to what the cause of autism is, when it is nature and nurture combined together. Unfortunately, through the years with autism,

there's just been wide speculation what the causes are. And there's been no evidence to what the causes are,

but there's been beliefs that the causes are environmental in nature. And so we've looked at all sorts of environmental issues that haven't been proved to be the cause.

We've looked at causes from the mother being a refrigerator mother, which it was initially thought to be. And how devastating is that, to think the mom

is a cause of autism, despite no scientific evidence that is so? Luckily we've dismissed that years ago.

We've got to be careful when we look at the cause of autism, because, often we get into blaming certain individuals.

We often get into looking at environmental issues that don't exist. We simply do not know the cause of autism. [AUDIO LOGO]