Adderall May Have Unhinged Lindsay Lohan

May 5: Lindsay Lohan parties with her mom Dina at Las Palmas club for Cinco de Mayo. (X17Online.com)

Lindsay Lohan's Adderall dependence -- the result of a medical misdiagnosis -- may have been the reason she went off the rails.

As TMZ first reported, the docs at the UCLA rehab facility believe Lindsay was misdiagnosed with Attention Deficit Hyperactivity Disorder, and then prescribed Adderall to treat the phantom affliction.

Dr. Joe Haraszti, a prominent L.A. addiction specialist  tells TMZ that people who take Adderall when they don't need it can experience similar effects as people who use cocaine or methamphetamine.

Haraszti says people who unnecessarily take Adderall can display manic symptoms and often do things like "driving around until all hours of the morning,  smoking heavily, tweeting and texting all night long." The doc adds, "They can become very impulsive."

The doc also notes that people in that situation "might then complain of insomnia and then take Ambien or other sleep aids to help fall asleep in a vicious cycle"

Dr. Marc Kern, another addiction expert, tells us alcohol abuse is also very common among patients who take Adderall.

Dr. Kern tells us, "The Adderall counteracts the sedative side effects of alcohol use … making these people often drink more than someone who does not take the drug."

Bottom line -- a bad medical diagnosis may have set the ball rolling that unhinged Lindsay's life.