Dementia affects one-third of all people older than 65 years in the United States. The most common cause of dementia is Alzheimer’s disease, a progressive, irreversible brain disease that results in impaired cognitive functioning and other behavioral changes. Humans are considered uniquely susceptible to Alzheimer’s disease, potentially due to genetic differences, changes in brain structure and function during evolution, and an increased lifespan. However, a new study published Aug. 1 in Neurobiology of Aging provides the most extensive evidence of Alzheimer’s disease brain pathology in a primate species to date. Researchers from Kent State University’s College of Arts and Sciences, along with colleagues from the George Washington University, Yerkes National Primate Research Center, Georgia State University, Barrow Neurological Institute and the Icahn School of Medicine at Mount Sinai, found that the brains of aged chimpanzees, our closest living relatives, show pathology similar to the human Alzheimer’s disease brain.