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