he had an addiction, perhaps more than one; addiction changes and affects your entire life; once you battle an addiction and overcome it, your mindset completely changes.
Probably drug abuse.
Simple he is open about it with the world! Simple I say!
Do you think he went to rehab just to see if he could hook up with Lindsay Lohan ?
Drugs effect each person differently! Hell look at the drug adds on TV with all the possible side effects! Drugs in Charlie's body mixed poorly with the chemicals in his brain! There fore the change in personality. If that were not true then why do they give people with mental diagnosed mental disorders drugs like Lithium and such! I don't care if all the people in Hollywood do drugs and over dose; there are plenty of starving actors/actresses to take their place!