Demographic information including age, gender, frequency and duration of prior corticosteroid therapy and current anticipated dose and duration will be collected at baseline. Baseline measures of mood will be assessed with the Activation subscale of the Internal State Scale (ISS) (primary measure), Hamilton Depression Rating Scale (17-item version), and Young Mania Rating Scale (YMRS). Cognition will be assessed with the RAVLT (primary measure), Stroop, and Digit Span Backwards. The subjects will be given memantine (10 mg), riluzole (50 mg), or identical appearing placebo 1 tablet daily for 3 days and then at the first follow up appointment (day 3) the dose will be increased to BID if no side effects are reported. The subjects will be reassessed twice, at day 3 and day 7. Mood and cognitive measures will be repeated. The study visits will last approximately an hour and a half. Participants will discontinue memantine when they discontinue prednisone. The RA administering assessments will be blinded at all times. Alternative but equivalent versions of the RAVLT and Digit Span Backwards will be given to minimize practice or learning effects. Current and cumulative corticosteroid dose (mg each day X number of days) will be determined and recorded.