In the case of missing data we will use the last observation carried forward. In our lamotrigine study in a similar population, we found a change in the total words recalled on a word list and on the Stroop. Assuming a similar change with memantine and using double-sided, paired t-tests, we could detect a difference with a change in the placebo group with participants on the HVLT-R and with participants on the STROOP. Thus, although this is primarily a pilot study to obtain effect sizes for future, larger trials funded by NIH, it should have power to detect clinically meaningful differences between medication and placebo.