Brain’s ‘Fertility’: New Neurons & Alzheimer’s – Latest Study
The quest to understand what separates healthy cognitive aging from decline has taken a significant step forward. A new study published in Nature reveals a key difference in the brains of “superagers”— individuals over 80 who maintain cognitive abilities comparable to those decades younger—and their peers. Researchers have found that superagers exhibit a remarkably higher rate of neurogenesis, the creation of new neurons, in the hippocampus, the brain’s memory center.
For decades, the prevailing view was that neurogenesis significantly slowed with age. However, this research confirms that the human brain continues to grow new neurons throughout life, even well into the ninth decade. The study, conducted by researchers at the University of Illinois Chicago (UIC), Northwestern University, and the University of Washington, examined brain tissue from individuals across a range of ages and cognitive statuses, including young adults, healthy older adults, superagers, and those with Alzheimer’s disease.
The findings demonstrate a stark contrast. While young and healthy older adults showed ongoing neurogenesis, superagers exhibited a rate of new neuron production double that of their healthy counterparts. Conversely, individuals with Alzheimer’s disease showed negligible to zero new neuron growth, strongly suggesting a link between the loss of neurogenesis and cognitive failure. This observation aligns with previous research showing minimal new neuron production in brains affected by Alzheimer’s, as highlighted in a recent report from Neuroscience News.
Researchers meticulously tracked the development of these new neurons, categorizing them into three stages: stem cells, neuroblasts, and immature neurons—analogous to “babies, toddlers, and teenagers” in the cellular world, as described by Orly Lazarov, a professor at UIC and director of the Alzheimer’s Disease and Related Dementia Training Program. This detailed analysis confirmed active growth and differentiation of neurons within the hippocampus of superagers.
Beyond the sheer quantity of new neurons, the study also revealed differences in their “epigenetic signatures.” These signatures, essentially blueprints that dictate how cells respond to environmental changes, were distinct in superagers, suggesting their new neurons are better equipped to adapt and withstand stress. This resilience at the cellular level may contribute to their exceptional cognitive function.
“This is a big step forward in understanding how the human brain processes cognition, forms memories and ages,” says Lazarov. “Determining why some brains age more healthily than others can help researchers make therapeutics for healthy aging, cognitive resilience and the prevention of Alzheimer’s disease and related dementia.”
The discovery builds upon earlier research, initially conducted in rodents, that demonstrated the possibility of adult neurogenesis. Subsequent studies in primates further strengthened the link between neurogenesis and healthier brain aging, particularly in relation to memory formation and processing. This latest study solidifies the evidence that neurogenesis occurs in adult humans as well.
However, researchers caution that the sample sizes in the superager group were relatively small, with each group containing ten or fewer individuals. This limits the statistical significance of some findings, as noted by Maura Boldrini Dupont, a neuroscientist at Columbia University. Further research with larger cohorts is needed to confirm these observations and explore the underlying mechanisms driving neurogenesis in superagers.
The implications of this research extend beyond simply understanding healthy aging. Identifying the factors that promote neurogenesis could pave the way for novel therapeutic interventions aimed at preserving cognitive function and preventing neurodegenerative diseases like Alzheimer’s. Researchers are now investigating the role of lifestyle factors, such as diet, exercise, and inflammation, in modulating neurogenesis and its impact on brain health. As Jalees Rehman, a researcher at UIC, points out, increasing lifespan must be accompanied by a commitment to maintaining cognitive health. Understanding the molecular basis of neurogenesis and its epigenetic regulation could unlock new strategies for preserving memory and cognitive function as we age.
While the exact “secret” to superaging remains elusive, this study provides a crucial piece of the puzzle, highlighting the remarkable plasticity of the human brain and the potential for continued growth and resilience even in advanced age. The findings offer a hopeful outlook for the future of cognitive health and the development of interventions to promote healthy brain aging for all.