A study is underway at Saint Louis University School of Medicine to test the effectiveness of the antidepressant Lexapro on people between the ages of 65 and 90. Doctor Philip Lefevre is the principal investigator of the study. He says this drug, which has already been approved by the Food and Drug Administration, has not really been tested to any great degree on the elderly. The drug is already being used by the elderly, but there is no conclusive information regarding how beneficial the drug is to this group.