Brooke Mueller, the ex-wife of Hollywood actor Charlie Sheen, is in rehab undergoing treatment for drug addiction, her attorney said. The move comes after she suffered an overdose of the psycho-stimulant Adderall last week and was hospitalized, TMZ said. She checked into an undisclosed treatment center Monday night, but it is unclear how long she will be there. \"Brooke was uncomfortable with the way Adderall was making her behave,\" Mueller\'s attorney, Yale Galanter, told the celebrity news website, confirming her rehab stay. Mueller has been to rehab more than 15 times to undergo treatment for drug and alcohol abuse, TMZ said. She and Sheen, who has battled his own substance abuse issues for years, are the parents of twin 3-year-old sons. The couple married in 2008, separated in 2009 and were officially divorced last year.