The behavioral and psychological symptoms of dementia (BPSD) are common serious problems that are a major contributor to caregiver burden. Despite their significance, the underlying neurobiology of these disturbances is still unclear. This review examines the role of norepinephrine (NE) on BPSD, including depression, aggression, agitation and psychosis. A number of lines of evidence suggest that NE dysfunction leading to BPSD may result from increased NE activity and/or hypersensitive adrenoreceptors compensating for loss of NE neurons with progression of Alzheimer's disease (AD). With greater appreciation of the underlying neurobiology of behavioral and psychological symptoms of dementia (BPSD) more effective, rational, targeted pharmacotherapy will hopefully emerge.