The purpose of this study is to determine whether taking the medication memantine reduces impairment of memory and attention associated with electroconvulsive therapy.

The primary objective of this study is to determine whether the novel NMDA antagonist memantine, FDA approved for use in moderate to severe alzheimers dementia, may reduce the neurocognitive deficits associated with right unilateral ECT treatments in patients receiving ECT for a severe and relatively refractory Major Depressive episode.

Our hypothesis is that the use of an NMDA antagonist would reduce intracellular calcium levels, and glutamatergic stimulation during ECT. This reduction in excitatory stimulation during ECT would reduce hippocampal and prefrontal neuronal endangerment and dysfunction, thereby reducing cognitive impairment associated with right unilateral ECT treatments. We also hypothesize that ACTH and cortisol levels will correlate with neurocognitive impairment in placebo treated subjects, but not in the memantine treated individuals.

Inclusion Criteria::

• Meets DSM-IV criteria for Major Depressive Disorder
• 18 to 75 years of age and able to provide legal consent
• Referred to Stanford ECT service by treating physician for unilateral electroconvulsive therapy with inpatient hospitalization
• Competed process for consenting to the clinical use of ECT according to California State law
• Females of childbearing potential will be required to use a double-barrier method of contraception, which includes foam and either condom and diaphragm, IUD, and/or implant during study.
 Exclusion Criteria:- Treatment with ECT in the 6 months prior to screening
• Meets criteria for drug or alcohol abuse or dependence in the 6 months prior to screening
• Use of alcohol or illegal drugs within seven days of randomization or during study. Patients may be excluded for use during a period greater than 7 days, per study physician's discretion
• Presence of unstable or untreated cardiovascular disease, hypertension, or endocrine disorder as determined by the investigator
• use of antipsychotic, antidepressant, or other prescription medications unless dose is stable for at least 7 days prior to randomization.
• Use of any investigational treatment within 30 days of randomization
• Previous allergic reaction to memantine or drugs of similar chemical structure.
• Women who are pregnant or breastfeeding are not advised to participate in the research study
• Any neurological disorder or organic brain condition that would confound neurocognitive testing

No individual data will be available