The first part of the present review describes the current status of elderly people with behavioral and psychological symptoms of dementia (BPSD) in the community and basic viewpoints for differentiating between different forms of dementia. Specifically, it focuses on four points among the data and research related to determining the current status of elderly people with BPSD. We also propose basic concepts for differentiating between the core symptoms of dementia and BPSD, BPSD and delirium, and agitation and delirium. In the second part of the present review, various aspects of the symptom 'agitation' are discussed based on the experience of our home visit medical service for people with dementia by describing two cases. In cases such as Case 1, where the subject was given high doses of antipsychotics, we believe the problem was that the physicians immediately abstracted all of the abnormal behavior in the subject's life as 'agitation', and provided treatment to the subject accordingly. In Case 2, where the subject had dementia with Lewy bodies (DLB), we propose that it is crucial to differentiate clearly between agitation and delirium. Both of these cases show the risks of focusing treatment simply on agitation. When BPSD occurs in a person with dementia, the burden on caregivers increases. At such times, physicians tend to side with the family rather than with the patient. However, medical care is intended to be for the afflicted person, and physicians should base their plans for medical intervention on this principle.