"I have battled with bouts of depression right throughout my life and it got to a point where I was so desperate to relieve it I started to experiment with drugs," Ablett said.
"But it was some time before I started to realise just how destructive it was, spiritually, emotionally, relationally, financially. It affects every area of your life."
Ablett's new book is due to be released soon and the footballer stressed that he was speaking publicly as he did not wish to profit from the Horan incident detailed within.
"It's a football book and I don't think it's appropriate, and I don't want to be in any way profiting from that tragedy," said Ablett.