Brown did include this quote in her book Sudden Death (Bantam Books, New York, 1983), p. 68, but it appears she was just paraphrasing a quote that had already been written elsewhere. The earliest known appearance of a similar quote is the "approval version" of the Narcotics Anonymous "Basic Text" released in November 1981, which included the quote "Insanity is repeating the same mistakes and expecting different results." A PDF scan of the 1981 approval version can be found here http://www.nauca.us/wp-content/uploads/2015/04/1981-11-Basic-Text-Approval-Form-White.pdf, with the quote appearing on p. 11 (p. 25 of the PDF), at the end of the fourth paragraph (which begins "We have a disease; progressive, incurable and fatal"). More in this article https://quoteinvestigator.com/2017/03/23/same/ on Quote Investigator website.
Misattributed