Inclusion Criteria: Bulimia Nervosa

• Participants must meet DSM-IV criteria for a current diagnosis of bulimia nervosa as determined by the Structured Clinical Interview for DSM-IV (SCID) and Eating Disorder Examination (EDE).
• Participants must report an average of 3 or more binges and vomiting episodes per week in the 2-week period prior to the screening visit.
• Male or Female between 18 and 65 years of age, inclusive.
• Female participants must be: postmenopausal for at least one year, surgically sterile, or practicing an effective method of birth control (e.g., prescription oral contraceptives, contraceptive injections, intrauterine device, double-barrier method, contraceptive patch, male partner sterilization, abstinence and agreeing to continue abstinence or to use one of the acceptable methods of contraception just enumerated should sexual activity commence) before entry and throughout the study; and have a negative serum pregnancy test at the screening visit.
• Participants must have observed a designated washout period of at least seven days or a period equal to five half-lives of prohibited medications.
• Participants must be able to take oral medication, adhere to the medication regimens, and be willing to return for regular visits.
• Participants must be able and willing to read and comprehend written instructions and comprehend and complete all scales and questionnaires required by the protocol.
• Participants must have signed an informed consent document indicating that they understand the purpose of and procedures required for the study and are willing to participate in the study.

Inclusion Criteria: Body Dysmorphic Disorder

Inclusion criteria for participants with body dysmorphic disorder are identical to those for bulimia nervosa above, with the following differences in the first two criteria:

• Participants must meet DSM-IV criteria for a current diagnosis of body dysmorphic disorder as determined by the SCID.
• Participants must exhibit a score of ≥ 20 on the BDD-YBOCS at a score of ≥ 5 on the first three items of the BDD-YBOCS, which are the items that assess the DSM-IV criteria for BDD.

Exclusion Criteria for both Bulimia Nervosa and Body Dysmorphic Disorder:

• Participants with a lifetime diagnosis of schizophrenia, other psychotic disorder, or bipolar disorder as defined by DSM-IV and supported by the SCID.
• Participants with clinically significant current depression or who, in the investigators' judgment, might require intervention with either pharmacological or non-pharmacological therapy for major depressive disorder over the course of the study.
• Participants judged clinically to be at suicidal or homicidal risk by the study physician.
• Participants meeting DSM-IV criteria for any form of substance dependence or abuse (with the exception of nicotine or caffeine dependence) within 3 months prior to the screening visit.
• Participants meeting DSM-IV criteria for anorexia nervosa within 3 months prior to the screening visit.
• Participants with a current DSM-IV diagnosis of an organic mental disorder.
• Participants who have begun to receive formal psychotherapy (cognitive-behavioral therapy, interpersonal therapy or self-guided cognitive-behavioral therapy) for bulimia nervosa within 6 months prior to the screening visit.
• Participants who display a positive urine screen for drugs of abuse (phencyclidine, cocaine, amphetamines, tetrahydrocannabinol, and opiates) at the screening visit.
• Participants who have previously received memantine for any reason.
• Participants who have received an investigational medication within 30 days of the screening visit.
• Participants who are pregnant or lactating.
• Participants with a BMI less than 18.5 or greater than 35.
• Participants who have abused ipecac as a method of purging within the past 2 years.
• Participants who exhibit a serum potassium level of less than 3.0 mEq/L.
• Participants with thyroid-stimulating hormone concentrations outside the range of 0.5-5.0 lU/mL.
• Participants with clinically significant or unstable medical conditions
• Participants who in the opinion of the investigator should not be enrolled in the study because of the precautions, warnings or contraindications sections of the prescribing information for memantine
• Employees of the investigator, individuals with direct involvement in studies under the direction of the study investigators, as well as family members of the employees of the investigators.