Drugs are prepared to shoot intravenously by a user addicted to heroin, February 6, 2014.
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Everything you need to know about drugs

Updated

Did you know “meth mouth” is fake? Or that meth has the same effect on the brain as Adderall? Oh, you probably think crack cocaine addicts can’t think rationally, but actually they can…and they do! Columbia Professor Dr. Carl Hart sits down with Chris Hayes for an extended interview to debunk the myths we buy into surrounding drug addiction.

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Everything you need to know about drugs

Updated