Symptomatic domains in dementia include cognition, ADLs and behaviour. One can even add a domain of changes in motricity, since patents with AD will manifest some features of parkinsonism late in the disease. In many patients early changes in mood and anxiety precede the formal diagnosis of AD, sometimes with spontaneous improvement as insight into the disease is lost. Cognitive and functional ADL decline are relatively linear over time, whereas BPSD uctuations through the course of the disease resolves spontaneously through the severe stage as motricity becomes impaired (Gauthier et al., 2001). ese natural uctuations in the intensity of individual symptomatic domains through the stages of AD have an impact into trial design and outcomes (Table 56.2). It should be noted that studies can be of shorter duration and/or of smaller numbers of subjects in moderate stage compared to mild stages of AD because of the faster rate of decline in the former, which may be related to the sensitivity of measurement scales or to the progression of AD in the particular patient.