Hard-partying "Mean Girls" star Lindsay Lohan will be treated for methamphetamine addiction and a mental disorder that causes wild mood swings when she goes into rehab, the gossip website TMZ.com reported today. Lohan, 24, will be treated for meth addiction and bipolar disorder during her 90 days of court-ordered rehab following her release from jail this week -- which could happen as soon as today, her lawyer said. The site also quoted a person familiar with the case as saying methamphetamine -- a highly-addictive stimulant also known as crystal meth -- and opiates are Lohan's "drugs of choice." Opiates are...