Is Alzheimer’s Disease Unique to Human Beings?

Researchers at Kent State University have discovered tell-tale signs of Alzheimer’s disease in the brains of elderly chimpanzees, rekindling the debate about whether humans are the only species that can develop this debilitating dementia. A definitive diagnosis of Alzheimer’s includes two specific changes in the brain: amyloid plaques and neurofibrillary tangles. Many primates develop brain plaques as they age, but the tangles had been previously specific to humans. The new study, though, found that 13 of the 20 brains of deceased chimps showed amyloid plaques, and four also had the neurofibrillary tangles.

How the brain is compromised:

• Amyloid plaques are sticky accumulations of protein known technically as amyloid beta peptides.
• Neurofibrillary tangles are formed when proteins called tau create a knot of filaments that twist around each other like ribbons.
• Chimps are considered endangered in the US and cannot be used for invasive research. The brains studied were from chimps aged 37 to 62 that had died naturally at zoos and other facilities.