A new review has been published in Aging (listed by MEDLINE/PubMed as “Aging (Albany NY)” and “Aging-US” by Web of Science), on October 29, 2024, Volume 16, Number 20, entitled “Brain Aging and Alzheimer’s Disease, A Perspective of Non -human primates.”
In the review, Ferrer Isidro of the University of Barcelona and Reial Acadèmia de Medicina de Catalunya examines the differences in brain aging and Alzheimer’s disease between humans and their closest evolutionary relatives, such as chimpanzees, baboons and macaques. The study highlights that while humans are particularly susceptible to severe cognitive decline and memory loss caused by Alzheimer’s disease, non-human primates typically experience only mild changes as they age.
Alzheimer’s disease affects more than 50 million people worldwide, making it critical to understand how aging affects the brain. This review sheds light on the differences between humans and non-human primates and reveals that although brain aging in primates involves some structural and protein changes, it does not result in the toxic protein deposits that cause Alzheimer’s disease in humans.
In humans, harmful tau protein deposits, known as tau tangles, appear early in life and spread widely throughout the brain, damaging cells and contributing to memory loss. In non-human primates, tau tangles are rare and usually confined to small areas. Although primates can develop beta-amyloid deposits – fragments derived from amyloid precursor protein – these deposits are less toxic and do not interact with tau tangles to cause Alzheimer’s-like symptoms. Aging primates undergo only mild memory or behavioral changes, avoiding the severe cognitive decline and dementia common in humans.
Humans’ unique vulnerability to Alzheimer’s disease may be related to traits that have emerged through evolution, including larger brains, longer lifespans and higher cognitive skills. These adaptations may come at a cost, making the human brain more susceptible to aging-related damage.
This review also suggests that tau tangles play a more crucial role in Alzheimer’s progression than previously thought. While traditional treatments focus on targeting beta-amyloid deposits, this study highlights the need to shift focus to tau pathology. The work challenges the widely accepted amyloid cascade hypothesis, which suggests that beta-amyloid is the main cause of Alzheimer’s disease. Instead, it points to tau tangles as the first and most damaging change in the human brain. This insight could encourage new treatments that focus on preventing or reducing tau deposits.
The findings also highlight the value of studying non-human primates to understand why their brains are more resistant to severe aging-related damage. By identifying protective mechanisms in primates, researchers may discover new strategies to slow or prevent Alzheimer’s disease in humans.
“These observations show that human brain aging differs from brain aging in non-human primates, and humans are the exception among primates in terms of severity and extent of brain aging damage.”
In conclusion, this review not only improves our understanding of why people are particularly vulnerable to Alzheimer’s disease, but also opens new avenues for investigating innovative strategies to combat aging-related brain damage in humans.
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Magazine reference:
Isidro, F. (2024). Brain aging and Alzheimer’s disease, a non-human primate perspective. Aging. doi.org/10.18632/aging.206143.