Patients with Alzheimer's disease (AD) show high incidence of behavioral and psychological symptoms (BPS).The occurrence of BPS has a great impact on the patients and caregiver's quality of life, increases caregiver's burden, and in many cases precipitates admission of the patients to a geriatric center. On the other hand, the importance of the BPS is increasing because most of them are susceptible to being treated effectively, mainly thanks to the use of drug measures and behaviour modification techniques. This study describes the pathophysiological mechanisms of BPS in AD and its relationship with cognitive and functional impairment of patient and caregiver's burden and current therapies.