Adrien Brody was "seriously depressed" for a year after making The Pianist.

The 39-year-old actor - who, at 29, became the youngest person to win the Academy Award for Best Actor for his role in the drama - admits playing a Polish-Jewish musician in the World War II film took its toll because he had immersed himself so deeply in the role.

"It was all consuming. For a good year after, I was probably seriously depressed. There were severe transitions that I put myself through physically and emotionally... I shot it when I was 27, and that was my real awakening and entrance into adulthood, that responsibility, and awareness of my own good fortune that I had taken for granted," said Adrien, who lost a substantial amount of weight for the film.

The Detachment star - who began acting when he was 13 years old - thinks he was mature and sensible from a young age because being an only child meant he had to take responsibility for his actions: "I think it forced me to be mature, because I had to be accountable when I came home. I couldn't run off and blame it on my brother or sister. I had to be accountable."