Creatine for Depressed Male and Female Methamphetamine Users

Inclusion Criteria:

* Current primary diagnosis of methamphetamine dependence or abuse, with methamphetamine preferred drug of abuse
* Current diagnosis of major depressive disorder (primary or substance-induced)
* Current diagnosis of an anxiety disorder (primary or substance-induced)
* Current Hamilton Depression Rating scale score \> or = to 16
* Current Hamilton Anxiety Scale score \> = to 18
* If taking a psychotropic medication for depressed or anxious mood, regimen must be stable for \> = to 4 weeks prior to creatine treatment initiation

Exclusion Criteria:

* Persons unable to provide adequate informed consent
* Persons who are at clinically significant suicidal or homicidal risk
* Primary substance-related diagnosis other than methamphetamine dependence or abuse
* Positive pregnancy test (females only)
* History of renal disease
* Clinically significant medical or neurological illness identified by history, physical exam and laboratory testing
* History of hypersensitivity reaction to creatine