LEIGH SALES, PRESENTER: What would you do if your happy, promising child suddenly turned into a completely different person? A Sydney couple spent the past eight years grappling with exactly that question. When their only son was 18 months old he went into a rapid decline and was diagnosed with severe autism. Now the family's experience is documented in a new book, as Sarah Dingle reports.
KATHY CAHILL, MOTHER: I guess every parent wants to think that their child will be able to exist in the world, um, or have a place in the world.
SARAH DINGLE, REPORTER: Alex Macris is only nine, but already he's been on a journey few can imagine.
ANTHONY MACRIS, FATHER: Alex started off really well, you know. We didn't see it coming.
SARAH DINGLE: In 2001, Anthony Macris and his partner Kathy Cahill became proud first-time parents. They were so delighted by their bright little son, they were soon planning his university career.
ANTHONY MACRIS: Alex developed pretty much as a normal kid. He did fantastically. We were really pleased and proud of him.
KATHY CAHILL: He did have a lot of language and he was quite aware of what he wanted to do and the things he wanted to do.
SARAH DINGLE: Then small, worrying changes began to appear in their son's behaviour.
KATHY CAHILL: The first signs were things like him reversing words. I'd be going on a walk with him and we'd pass houses that we normally did pass, and I remember one particular letterbox he used to run up to and he'd point to a horse on the letterbox and he'd say, "horse". And one day we went past and he said, "saw." And I thought, "Mmm, OK."
ANTHONY MACRIS: But there seemed to be this kinda period around two where it kind of accelerated and I think we just watched in stunned amazement.
KATHY CAHILL: All of a sudden it seemed to crash. He couldn't cope with childcare anymore. He started to lose more and more words, and, um, eventually he didn't have any.
SARAH DINGLE: At his lowest point, Alex Macris didn't even recognise his parents. After months of tests, a diagnosis finally provided them with the answer they'd been dreading.
KATHY CAHILL: He has autism. He's low-functioning autism.
ANTHONY MACRIS: It was probably the worst period I've ever lived through. You have this beautiful child and you are essentially watching them disintegrate. ... The spirit I wrote the book in was the world has to know. It was a very hard book for me to write.
SARAH DINGLE: Anthony Macris tried to make sense of his family's experience. 'When Horse Became Saw' is a raw account of his shock and bewilderment at his son's regression into severe autism, where the old Alex had disappeared and the future of the new Alex hung in the balance.
KATHY CAHILL: We were watching in horror, trying to take in the information that our son had autism, not being given any information on what we could do with him, and being told that we - there was really nothing we could do.
SARAH DINGLE: For both parents, doing nothing was not an option. Alex's situation demanded that they rise to the challenge.
For Kathy Cahill, it meant abandoning a career she loved as a dancer to devote all her time to her son. With little professional support, she became a self-taught therapist.
ANTHONY MACRIS: And Kathy really fantastically took charge of the situation.
SARAH DINGLE: This was the start of years of an intensive and expensive one-on-one behavioural program for Alex to give him the best possible chance at life.
ANTHONY MACRIS: The stress it puts on you is enormous. But your life's not about you anymore.
SARAH DINGLE: Slowly there were small gains, moments of connection and more words.
KATHY CAHILL: You could see things moving, you know, and things were more positive again, you know, because every day you'd see him learning something else.
SARAH DINGLE: Now nine, Alex Macris is incredibly sure-footed, but language still comes less easily.
KATHY CAHILL: He can ask for his basic needs to be met. He can tell us when he's angry or happy or sad, those sorts of things. But I think more complicated exchanges are difficult for him still.
SARAH DINGLE: Autism has changed not only Alex Macris, but his father and his mother forever.
KATHY CAHILL: I've sort of forgotten the child that was, to a degree.
ANTHONY MACRIS: This is the child who we've sort of been given, and this is the child who we have to love, so we'll have to love him no matter what he's like. That's really all it comes down to.
LEIGH SALES: Sarah Dingle reporting.