 BPSD in institutionalized patients with severe AD is a serious public health problem. The effectiveness of current pharmacological management of BPSD with atypical antipsychotics is modest at best, and there are serious safety concerns including increased cerebrovascular adverse events and increased mortality. Preliminary data with memantine suggests this medication may be helpful for treating BPSD in the severe subgroup of the Alzheimers disease patient population. It is for this reason we propose an open-label prospective study of memantine in institutionalized patients with severe Alzheimers disease and significant BPSD. 