Frankie Muniz was 15 when he was nominated for an Emmy for Outstanding Lead Actor in a Comedy Series.

He was the star of Malcolm in the Middle,the critically acclaimed family sitcom that ran for seven seasons, with a debut audience of 23 million. Actors such as Emma Stone, Hayden Panettiere, Susan Sarandon, and Heidi Klum guest starred on the show, as well as celebrities like Magic Johnson. For a young actor, it was the opportunity of a lifetime.

But Muniz, now 32, doesn’t remember a moment of it.

He couldn’t tell you anything about attending the Emmys, or what it’s like to haveBreaking Bad’sBryan Cranston play your on-screen father.

In October last year, while Muniz was appearing onDancing with the Stars,the show ran an episode with the theme ‘Most Memorable Year’. Being asked to recall events from his childhood and adolescence, he made the matter-of-fact statement that he has no memory of being onMalcolm in the Middle.

Frankie Muniz and Bryan Cranston as Malcolm and dad Hal in Malcolm in the Middle. Image via 20th Century Fox.

"I'm not actually sure how my memory loss started," he said. "I have had nine concussions and I've had a fair amount of mini-strokes."

"I've never been to the doctor and been like, you know, 'Why don't I have a memory?' To be honest, I've never really talked about it.

"It makes me a little sad. Things pop back into my mind that I should have remembered."

Speaking to Entertainment Weekly after his appearance onDancing with the Stars, Muniz said he had his first 'mini-stroke' (otherwise known as a transient ischemic attack - involving a temporary blockage in the brain) in 2012. He was riding a motorbike and suddenly lost his peripheral vision, and when he returned home, he couldn't recognise his mum or girlfriend. When he went to the hospital, he was given no definitive answers.

"I’m 31, I’ve never sipped alcohol, I’ve never touched a drug or taken a drag of a cigarette," he said. "The only thing I’ve felt was stress. I’m a high-strung person. I just like to always be moving. I’m not good at relaxing."

Despite not understanding his condition, Muniz said, "It’s not something I think about. I don’t go, ‘Oh man I’m really scared, I really need to know.' I just move forward."

During an interview on the reality show, Muniz said his girlfriend Paige Price keeps a detailed diary to help with his memory loss.

"I love to be able to look back," he said, adding that while he can't remember his trip to Australia in 2016, he's seen pictures. "I was on top of the Sydney Harbour Bridge... but I don't remember climbing it," he said.

In a package forDancing with the Stars,formerMalcolm in the Middleco-star Bryan Cranston said, "I told him not to worry about what you remember and what you don't remember. They're still your experiences".

"That will be my job. I will tell him, 'Remember this? Remember that from Malcolm? What a life for you'."

Despite his memory loss, Frankie Muniz says he's "happy".

"I'm happy with my acting career, I'm happy with the decision I made to drive race cars and to focus on music. Even if I don't remember it all, I'm happy."

You can read more information at strokefoundation.org.au.