Researchers studying chimpanzee brains have found the most extensive evidence to date of Alzheimer’s disease pathology in a primate.
However, researchers — including those from Kent State University — say more study is needed to determine whether the pathologies found in chimpanzee brains lead to age-related cognitive decline in the apes.
The new study — involving the brains of humans’ closest living relatives — could help researchers determine how humans develop Alzheimer’s and how to fight the disease.
Humans have been thought to be uniquely susceptible to Alzheimer’s disease.
The study was published Tuesday in the journal Neurobiology of Aging.
“Very few studies have investigated Alzheimer’s disease pathology in chimpanzees, the species closest in phylogeny [evolutionary history] and most genetically related to humans,” said senior author Mary Ann Raghanti, associate professor and interim chair of anthropology at Kent State, in a news release issued by the university.
“Brain samples from great apes, particularly aged individuals, are incredibly scarce, so a study this size is rare,” she said.
Analysis of chimpanzee brains for the study began in 2013 in Raghanti’s lab at Kent State. The 20 brains were provided by the National Chimpanzee Brain Resource, which collects the brains from animals that have died from natural causes at zoos and research centers.
Scientists are not absolutely sure what causes Alzheimer’s in humans, according to the Alzheimer’s Association.
But plaques of “sticky” beta-amyloid proteins and tangles — twisted bits of another protein called tau — are thought to be the major culprits in cell death and tissue loss in the Alzheimer’s brain, the association says.
By examining chimpanzee brain regions most affected by Alzheimer’s disease pathology in humans, the research group demonstrated that beta-amyloid plaques and blood vessels were present in aged chimpanzee brains.
Similar to humans, increasingly larger volumes of beta-amyloid plaques and deposits in blood vessels were found with greater age.
Tangles of the tau protein also were found.
Also involved in the study were researchers from the George Washington University in Washington, D.C.; Emory University’s Yerkes National Primate Research Center outside Atlanta; Georgia State University in Atlanta; Barrow Neurological Institute at St. Joseph’s Hospital and Medical Center in Phoenix; and the Icahn School of Medicine at Mount Sinai in New York City.
Lary Walker, a neuropathologist at Emory University’s Yerkes National Primate Research Center in Lawrenceville, Ga., who was not involved in the study, told Ryan Cross, writing for the Science magazine website, that he was not surprised by the study.
In 2008, Walker led a team that found both plaques and tangles in a study of a single, 41-year-old chimp that died from stroke, according to Cross’ article. . However, the distribution of plaques and tangles didn’t resemble those in human brains with Alzheimer’s.
Katie Byard can be reached at 330-996-3781 or kbyard@thebeaconjournal.com.
