Clinical observations leave little doubt that environment has a considerable effect on behavioral and psychological symptoms of dementia (BPSD), and many environmental interventions have been proposed and implemented in an attempt to manage behavioral problems in patients with Alzheimer's disease (AD). However, as Dr. Mintzer commented, there is no theoretical construct for validating environmental interventions. He pointed out the need for consensus on a hypothesis to be tested so that the value of environmental interventions can be proven.