Mark Ruffalo

The 55-year-old actor found school “difficult” because of the condition because he felt like an outcast.

However, the 'The Avengers' star assured youngsters growing up with the medical condition that there is hope.

He told the Child Mind Institute: "One of the things that was very difficult for me was grade school — feeling very strange and unique and freakish, feeling like I didn't fit in anywhere.

"I would say to ... my younger self then that there's help and that there are ways to deal with it and to manage it and to overcome it."