Keira Knightley reveals she was diagnosed with PTSD after suffering a mental breakdown at 22

Actress Keira Knightley opened up about having a mental breakdown at 22. (AP)

Keira Knightley has been in the entertainment industry since the age of six and has had her fair share of highs and lows.

In a new episode of The Hollywood Reporter's "Awards Chatter" podcast, the 33-year-old British actress gets candid about her quick rise to stardom, and the mental breakdown that ensued.

Breaking out in the 2002 indie film "Bend It Like Beckham" led Knightley to the "Pirates of the Caribbean" franchise and the rom-com "Love, Actually."

"That run of films was completely insane," Knightley recalls, however noting that most reviews focused on her looks. "It's amazing looking back at it from the outside -- you're like, 'Whoa, that was hit after hit after hit!' But, from the inside, all you're hearing is the criticism, really. And, also, I was aware that I didn't know what I was doing, you know? I didn't know my trade, I didn't know my craft. I knew that there was something that worked sometimes, but I didn't know how to capture that."

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Finding it hard to enjoy her newfound success and fame, she worked on her craft and was surprised to then receive an Oscar nomination for her role in "Pride & Prejudice." All the while, Knightley was still struggling with her celebrity.

"It was still very confusing, because you're getting all these nominations for all of these things, but press-wise, when I'm going into interviews, people are still saying, 'Everybody thinks you're sh*t,' or focusing on your looks, or focusing on what's wrong with you," she explains. "And, again, I was 19 [actually 20 when nominated] -- you can only hear the negative stuff."

"I did have a mental breakdown at 22, so I did take a year off there and was diagnosed with post-traumatic stress disorder because of all of that stuff," Knightley reveals. "I went deep into therapy and all of that, and she [the therapist] said, 'It's amazing -- I normally come in here and have people that think people are talking about them and they think that they're being followed, but actually they're not. You're the first person that actually that is happening to!'"

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She eventually began to feel much better about herself and stopped listening to the negative reviews and comments. She was also much more confident in her acting.

"I think the main thing that I'm very proud of myself for," she stresses, "is I learned my trade. I did it very publicly, but I have learned my trade, and technically, whatever you need me to do, I can deliver it. I want to get better and I'm not saying that there's not a ways to go — I want to keep learning and keep pushing myself -- but I'm in a good place where I feel pretty confident about what I can do."

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