Lindsay Lohan may have been misdiagnosed with and treated for Attention Deficit Hyperactivity Disorder, TMZ said Friday.

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The Web site said the U.S. actress has been taking the drug Adderall, but doesn't have the disorder with which doctors diagnosed her. Taking the drug when one doesn't need it could result in erratic behavior, doctors say.

Los Angeles addiction specialist Dr. Joe Haraszti told TMZ people who take Adderall when they don't have ADHD can experience similar effects as those who use cocaine or methamphetamine.

"The Adderall counteracts the sedative side effects of alcohol use -- making these people often drink more than someone who does not take the drug," another addiction specialist, Dr. Marc Kern, told TMZ.

The 24-year-old star of "Freaky Friday" and "Mean Girls" spent nearly two weeks in a solitary cell for violating probation in a 2007 driving under the influence case. Her sentence was cut short due to good behavior and jail overcrowding.

Despite her youth and promising career, Lohan has long battled an addiction to drugs and alcohol. She has been at a drug treatment facility since her Aug. 2 release from jail.