Robert Moore stopped smoking synthetic cannabis a year ago, but is still recovering from its effects and does not know when he will be "right" again.
The 24-year-old told the Herald last year that after four months of smoking Kronic, his life began to "fall apart".
He developed a daily habit, spending about $80 a day on Kronic, and hit "rock bottom".
Now living in Australia, Mr Moore said yesterday he was only just starting to feel almost back to normal.
"But I think it still has an effect. I can't drink any more because I get quite violent. That stuff definitely twists you up for a while," he said.
He said the lows he experienced after using Kronic were scary.
"It's a really dark place. You can only know what the psychological damage is when you've been there.
"I definitely feel better now, but it takes a while to get back from that dark place. It really sets you back a lot when you're using."
He thought it would take more than warnings from experts to stop most Kronic users. But he wanted to get the message across about long-term effects.
"Think about what you're doing to your brain ... It's pretty vulnerable and doesn't need the chemicals."
Read more: Alarm at Kronic suicide link