Serotonergic system, cognition, and BPSD in Alzheimer’s disease

•Behavioral and psychological symptoms of dementia (BPSD) present in Alzheimer's disease.•Certain BPSD in Alzheimer’s disease co-present and can be clustered into distinct domains.•Serotonergic system has been tied to cognitive decline and multiple BPSD domains.•This review summarizes the evidence for specific serotonergic system alterations in BPSD.