Sonia Rykiel attends the Sonia Rykiel Ready to Wear S/S 2012 show during Paris Fashion Week at Halle Freyssinet on Oct. 1, 2011, in Paris.

(Credit:Pascal Le Segretain/Getty Images)

(CBS News) French fashion designer Sonia Rykiel reveals in her new book that she has been suffering from Parkinson’s disease for the last 15 years.

According to Women’s Wear Daily, Rykiel, whose symptoms are becoming more visible, writes in “N’oubliez pas que je joue”(“Don’t Forget It’s A Game”), “I don’t want to show my pain. I resisted, I hesitated, I tried to be invisible, to pretend that nothing was wrong. It’s impossible, it’s not like me.”

The 81-year-old designer and her colleagues worked hard to conceal her illness. She was not allowed to be photographed with the cane that she had been using for several years, she confesses in the book, according to WWD.

The book, which is co-written with French journalist Judith Perrignon and published by L’Iconoclaste, is available now.