Open-Label Pilot Study of Namenda in Adult Subjects With ADHD and ADHD NOS

The primary objective of the study is to assess the efficacy and tolerability of a 12-week trial of memantine hydrochloride administered twice daily in 20 adults (ages 18-55) with ADHD and ADHD NOS. Improvement will be defined as: 1) changes from baseline on the investigator-rated DSM-IV based ADHD Rating Scale; 2) changes from baseline in a questionnaire aimed at assessing executive functions (BRIEF); and 3) changes from screening in a computerized neuropsychological battery (CANTAB). We hypothesize that memantine hydrochloride will be associated with improving ADHD symptoms and associated deficits in executive functions. We also expect that memantine will be well-tolerated with predictable adverse events.