Nonhuman primates at the intersection of aging biology, chronic disease, and health: An introduction to the American Journal of Primatology Special Issue on aging, cognitive decline, and neuropathology in nonhuman primates

Abstract

Aging across the Primate Order is poorly understood because ages of individuals are often unknown, there is a dearth of aged animals available for study, and because aging is best characterized by longitudinal studies which are difficult to carry out in long-lived species. The human population is aging rapidly, and advanced age is a primary risk factor for several chronic diseases and conditions that impact healthspan. As lifespan has increased, diseases and disorders of the central nervous system (CNS) have become more prevalent, and Alzheimer's disease and related dementias have become epidemic. Nonhuman primate (NHP) models are key to understanding the aging primate CNS. This Special Issue presents a review of current knowledge about NHP CNS aging across the Primate Order. Similarities and differences to human aging, and their implications for the validity of NHP models of aging are considered.Topics include aging-related brain structure and function, neuropathologies, cognitive performance, social behavior and social network characteristics, and physical, sensory, and motor function. Challenges to primate CNS aging research are discussed. Together, this collection of articles demonstrates the value of studying aging in a breadth of NHP models to advance our understanding of human and nonhuman primate aging and healthspan.

The sensory ecology of primate food perception, revisited

“…In humans, sensory function changes considerably across the lifespan 220–222 . However, little work has explored the role of age/developmental stage on sensory function or ecology in primates 223 . There are a number of interesting questions situated at the intersection of primate feeding ecology, learning, and sensory system development that suggests this will be a fertile area of research for future primate sensory ecologists in both field and lab settings.…”

“…[220][221][222] However, little work has explored the role of age/ developmental stage on sensory function or ecology in primates. 223 There are a number of interesting questions situated at the intersection of primate feeding ecology, learning, and sensory system development that suggests this will be a fertile area of research for future primate sensory ecologists in both field and lab settings. For example, how does chemosensation during pregnancy and infancy shape olfactory and taste preferences of infants and juveniles?…”

Early Alzheimer's disease‐like reductions in gray matter and cognitive function with aging in nonhuman primates

“…Upon inspection of middle‐ (< 16 years) and older‐aged (> 16 years) animals as distinct groupings, we discovered that many of these age‐dependent associations were present in the older‐aged individuals, but not in their younger counterparts. This difference across age groups may indicate that aging‐related declines in brain volumes may not become apparent until about 16 years of age in vervet monkeys, an age that equates to approximately 56‐ to 64‐year‐old humans 20 . Increasing evidence from clinical studies demonstrates that this age range represents a critical period in AD progression.…”

“…One factor that may underlie the human-NHP difference is the relative timing of menopause. 20 In women, menopause occurs around the age of 51, after approximately 42% of the lifespan (maximum age = 122.5 years). 20,78,79 In contrast, menopause has not been observed in chimpanzees in the wild, 80 ).…”

“…[18][19][20][21] NHPs are well established models of brain aging due to the many physiological, social, and anatomical characteristics shared with humans. 20,[22][23][24] Accumulating data suggest that NHPs undergo reductions in brain volume reminiscent of human aging, 19,[25][26][27][28] and several NHP models of AD indicate that elderly animals develop early ADlike neuropathologies, including the accumulation of amyloid beta (Aβ) plaques and hyperphosphorylated tau. 29 Diminished cognitive abilities with aging have been demonstrated in several species, including marmosets, 30,31 rhesus macaques, 32,33 and chimpanzees.…”