In a book to be released on Monday, "Twists and Turns,'' Mitcham reveals his battle with low self-esteem, anxiety and depression, panic attacks and repeated self-harm as a teenager, which helped begin his dependence on crystal meth.

Mitcham said that even after his Beijing gold medal win, he was still ranked No 2 – "I had still failed to achieve my childhood dream of becoming the best in the world at something,'' so he turned to drugs.

He said he knew the dangers of crystal meth, but "taking it was something I did . to take my mind off things that were upsetting me, to make me feel better about myself.''

Mitcham, who is openly gay, said in the book, excerpts of which were published in Fairfax Media on Saturday, that he has recovered from last year's drug problems with the help of Narcotics Anonymous, hypnotherapy and his family and friends.