A recently published study in Science determines whether it is possible for chimpanzees to develop Alzheimer ’s disease as they age.
Alzheimer’s disease is a type of dementia that causes problems with cognition, behaviour, and memory. Alzheimer’s is a progressive, debilitating disease with no cure. The full diagnosis occurs when dementia is accompanied by two distortions of the brain; amyloid plaques and neurofibrillary tangles. The amyloid plaque is formed when proteins known as amyloid-beta peptides are misfolded and become sticky. Neurofibrillary tangles occur when proteins called “tau proteins” form into long filaments that twist around each other like ribbons. This process and Alzheimer’s disease have so far only been documented in the human species. A recent article published in Science, however, suggested that elderly chimpanzees seemed to have the same signs of Alzheimer’s as humans. Anthropologist, Mary Ann Raghanti examined the brains of 20 chimps from the age of 37-62 years which is approximately equivalent to a human at the age of 120 for neurochemical signs of Alzheimer’s.
The test conducted on the chimps in this study showed that 13 had amyloid plaques and four had neurofibrillary tangles, which is usually seen in very advanced stages of Alzheimer’s in humans. Even though it could not have been said for sure that the chimps had Alzheimer’s disease, as they were not tested while alive for cognitive or behavioral changes, the tangles and amyloid plaques strongly suggested it is or related to the Alzheimer’s disease.
Further studies would need to be completed to confirm that the results are an indication of Alzheimer’s disease, but it would require research on living animals. Since there are many limitations on chimp research, if approved, further areas of research would be to analyze their sleep disorders, memory loss, disorientation, and socially inappropriate behavior. In addition, testing chimps for Alzheimer’s can also be useful to humans as chimps and humans are very closely biologically related.
Written by Seema N. Goolie, BSc
Alzheimer’s Association. (2017). What is Alzheimer’s? Retrieved from http://www.alz.org/alzheimers_disease_what_is_alzheimers.asp
Cross, R. (2017). Elderly chimps may get Alzheimer’s, renewing interest in studying these animals. Science. DOI : 10.1126/science.aan7152