Amanda Bynes was having a relatively quiet 2014 until yesterday, when she was arrested for driving under the influence of a "controlled substance." Today, TMZ reports that the substance was a stimulant: Adderall. She may have also been smoking weed.

Per TMZ:

We've learned the Adderall was prescribed by a doctor and she had taken the drug before getting stopped in Van Nuys Sunday and failing multiple field sobriety tests. She was arrested for DUI.

Adderall is a stimulant and we're told Amanda was "out of it" when she was stopped.

So even though Bynes is prescribed the ADHD medication, she was acting impaired. Yesterday, a California Highway Patrol spokesman told E! News, "Amanda was displaying symptoms that led us to believe she may have been under the influence of a stimulant. It possibly could be a combination of a stimulant and other drugs. We do not know."

TMZ speculates Bynes's old "weed problem" has resurfaced. She moved out of her parents' house earlier this month when her conservatorship ended, which TMZ cites as the starting point for this new round of trouble.

[Photo via AP]