The purpose of the study is to determine if cytidine 5'diphosphocholine (CDP-choline, a naturally occurring chemical in your body) has efficacy in reducing the methamphetamine craving of the subjects with methamphetamine dependence craving and helping them maintain the abstinence. In addition, investigators will measure the brain N-acetyl aspartate (a biologic marker for neuronal viability) level of participants to determine if brain deficits induced by methamphetamine may recover by taking CDP-choline.

Inclusion Criteria:

• 19-60 year-old male or female
• Methamphetamine dependence diagnosed by DSM-IV
• Total cumulative dose for methamphetamine during the last two years: over 10 gram (over 200 shots of 0,05 mgram intravenous methamphetamine injection)
• Methamphetamine use in recent 4 weeks
• Subscale score of drug use in ASI: >2

Exclusion Criteria:

• Significant current or past medical, neurological, or psychiatric co-morbidity including cardiovascular, renal, and endocrine disorder, as identified by medical history
• Lifetime axis I psychiatric disorders of bipolar disorder, schizophrenia, identified by SCID-IV
• Socially dysfunctional antisocial personality disorder
• Current alcohol or nicotine dependence identified by SCID-IV
• Taking psychotropic medication in recent two months
• Head trauma history with loss of consciousness or seizure
• Intelligence quotient < 80
• Pregnant subjects. In addition, women of childbearing potential who will not practice a medically accepted method of contraception will be excluded. Female subjects who are of child-bearing potential will have to pass a urine pregnancy test before each visit.
• Any contraindication to an MR scan