Lady Gaga struggled with her mental health after completing filming for House of Gucci.

In a new interview for British Vogue, the 35-year-old explained that in preparation for playing Patrizia Reggiani, she "lived" as her for a year and a half, including adopting her accent.

"It is three years since I started working on it, and I will be fully honest and transparent: I lived as her (Reggiani) for a year and a half," she told the publication. "And I spoke with an accent for nine months of that. Off camera, (too). I never broke. I stayed with her."

In order to "live" as Patrizia, who served 18 years in prison for the death of her ex-husband Maurizio Gucci, Gaga changed her hair colour and learned to see objects as "money".

"I started to live in a way whereby anything that I looked at, anything that I touched, I started to take notice of where and when I could see money," she continued. "I started to take photographs as well. I have no evidence that Patrizia was a photographer, but I thought as an exercise, and finding her interests in life, that I would become a photographer, so I took my point-and-shoot camera everywhere that I went. I noticed that Patrizia loved beautiful things. If something wasn't beautiful, I deleted it."

However, the pressures of method acting began to take a toll. By the end of filming, the Chromatica hitmaker experienced "psychological difficulty at one point," including dissociation from her surroundings while walking through Italy.

"I was either in my hotel room, living and speaking as Reggiani, or I was on set, living and speaking as her," Gaga recalled. "I remember I went out into Italy one day with a hat on to take a walk. I hadn't taken a walk in about two months and I panicked. I thought I was on a movie set."