Memantine Augmentation of Antidepressants

• Montgomery-Asberg Depression Rating Score (MADRS) [ Time Frame: Baseline & week 8 ]
  Higher MADRS score indicates more severe depression, and each item yields a score of 0 to 6. The overall score ranges from 0 to 60. Scores 0 to 6 indicate symptoms absent; 7 to 19 indicates mild depression; 30 to 34 defines moderate; 35 to 60 indicates severe depression. Changes in MADRS score was a primary measure.
  
  

• Modified Quick Inventory of Depressive Symptoms Self Report Scale (QIDS-SR) [ Time Frame: baseline & week 8 ]
  The 16 item Quick Inventory of Depressive Symptomatology (QIDS-SR16) (Rush et al. 2003) is designed to assess the severity of depressive symptoms, with higher scores representing more severe forms of depression. When complete, the QIDS are scored by summing responses to obtain a total score ranging from 0 to 27. Either appetite increase or decrease, but not both, are used to calculate the total score. Weight increase or decrease, but not both, are used to calculate the total score. Scores 0-5 indicate no severity of depression; 6-10 is mild; 11-15 is moderate; 16-20 is severe; 21-27 is very severe levels of depression. Participants were evaluated at baseline and at weeks 1, 2, 3, 4, 6 & 8.
  
  
• Hamilton Anxiety Rating Scale (HARS) [ Time Frame: baseline & week 8 ]
  Each item is scored on a scale of 0 (not present) to 4 (severe), with a total score range of 0-56, where <17 indicates mild severity, 18-24 mild to moderate severity and 25-30 moderate to severe. Scores > 30 indicate severe anxiety.
  
  
• Montgomery-Asberg Depression Rating Score (MADRS) [ Time Frame: baseline and week 8 ]
  Higher MADRS score indicates more severe depression, and each item yields a score of 0 to 6 on 10 items. The overall score ranges from 0 to 60. Scores 0 to 6 indicate symptoms absent; 7 to 19 indicates mild depression; 30 to 34 defines moderate; 35 to 60 indicates severe depression. Changes in response rate and remission rate were assessed for secondary measures.
  
  

- Objective

The objective of this study is to evaluate the efficacy and safety of 20 mg of memantine administered once daily as an augmentation agent for subjects who have been taking antidepressants for at least 1 month but who have experienced an incomplete or absent therapeutic response.

- Background

Memantine is a moderate affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist that is approved for the treatment of moderate-to-severe dementia of the Alzheimer's type. It has been commercially available in 23 countries worldwide since 1982.

There are reports in the published literature that suggest NMDA receptors may be involved in the etiology of depressive disorders. The NMDA antagonist ketamine has been shown to have antidepressant effects in a placebo-controlled clinical trial (Berman et al., 2000). Uncompetitive NMDA receptor antagonists, including memantine, have been shown to exhibit antidepressant-like activity in animal models of depression (Moryl et al., 1993, Papp and Moryl 1994). Animal studies also support the possibility that uncompetitive NMDA receptor antagonists may work synergistically in combination with antidepressants in animal models of depression (Rogoz et al., 2001). Some authors have hypothesized a role for NMDA receptors in the therapeutic effects of numerous antidepressants (Skolnick et al., 1996).

- Study Design and Duration

This is a randomized, single site, double-blind, placebo-controlled, parallel-group study in outpatients. The study consists of an 8-week double-blind treatment period. Approximately 25 patients will be randomized to each treatment group (memantine or placebo) for a total of approximately 50 patients.