Neuropsychiatric symptoms in Alzheimer's disease: Past, present, and future.

Noncognitive neuropsychiatric symptoms (NPS; e.g., depression, agitation) are nearly universal throughout the course of Alzheimer's disease (AD), cause significant adverse impact to patients and caregivers, and are associated with more rapid progression to severe dementia. Although the importance and presence of NPS was recognized by Dr. Alois Alzheimer himself, it was a series of research roundtables in the 2010s that propelled the understanding and treatment of NPS in AD forward. The mild behavioral impairment (MBI) construct was developed as a complementary behavioral analogue to mild cognitive impairment, solidifying the importance of NPS prior to dementia onset. Neurobiological underpinnings of NPS are being studied and the NPS treatment pipeline includes novel therapeutics, repurposing of existing pharmaceuticals, and non-pharmacologic interventions. The Alzheimer's Disease Research Centers and The National Alzheimer's Coordinating Center, being recognized in this special issue, have played a pivotal role in the recognition and study of NPS in AD. HIGHLIGHTS: Noncognitive neuropsychiatric symptoms (NPS) are nearly universal throughout the course of Alzheimer's disease (AD), cause significant adverse impact to patients and caregivers, and are associated with more rapid progression to severe dementia. A series of research roundtables in the last decade and a half have propelled the understanding and treatment of NPS in AD forward. The mild behavioral impairment (MBI) construct was developed as a complementary behavioral analogue to mild cognitive impairment, solidifying the importance of NPS prior to dementia onset. Neurobiological underpinnings of NPS are being studied and the treatment pipeline includes novel therapeutics, repurposing of pharmaceuticals, and non-pharmacologic interventions. The Alzheimer's Disease Research Centers and The National Alzheimer's Coordinating Center have played a pivotal role in the recognition and study of NPS in AD.