The X-Files actress revealed to the Guardian's Weekend magazine she has always struggled to retain information as she has "no memory" and can't remember much of what she learned in school or the plot of her favourite books.

However, the problem has worsened with age and she is considering getting herself tested to see if she could be suffering from the learning difficulty, which affects reading, writing, and spelling.

“Somebody had said to me that dyslexia isn’t just about seeing words backwards, it’s also about the assimilation of information," she said. "I’d always been afraid to look into it, because I was afraid that if I found something out, I would think that I couldn’t do anything that I wanted to do. I have this impression that I can do whatever I make up my mind to. But the reality is...”

Gillian is thankful that her memory issues have never affected her ability to learn lines and she's "terrified" they eventually might because then she'd "be b**gered.”

The 48-year-old has co-written a book called We: A Manifesto For Women Everywhere, a manual for self-improvement, with her close friend Jennifer Nadel and the book is interspersed with personal passages about her own mental health issues.

“There were times when it was really bad. There have been times in my life where I haven’t wanted to leave the house," she admitted to the publication before refusing to elaborate further.

The actress, who has been in therapy since she was 14, was a rebellious teenager and was once charged with trespass for breaking into her school on the night of her graduation to glue the locks shut. When asked if her addiction issues went beyond experimentation, she simply nodded and refused to say anything further.