New research has uncovered that older adults who maintain cognitive sharpness, often referred to as “super-agers,” possess a significant genetic advantage over their peers. Scientists at the University of Illinois College of Medicine in Chicago found that super-agers generate twice as many new neurons in the hippocampus, a critical brain region for learning and memory, compared to typical older adults. This study, published on March 15, 2024, in the journal Nature, sheds light on the molecular capabilities that enable super-agers to achieve high cognitive performance.
Study co-author Orly Lazarov, director of UIC’s Alzheimer’s Disease and Related Dementia Training Program, stated, “This discovery means that the super-agers have a molecular capability that allows them to have higher cognitive performance, and that includes more neurogenesis.” Neurogenesis, the process of generating new neurons, signifies a profound form of brain plasticity, suggesting that super-agers’ brains are more adaptable.
Understanding Super-Agers
A super-ager is defined as an individual aged 80 or older who demonstrates memory capacity equivalent to someone 20 to 30 years younger, as determined by delayed word recall tests. This term was coined by Dr. M. Marsel Mesulam, founder of the Mesulam Institute for Cognitive Neurology at Northwestern University. In their study, Lazarov and her team analyzed 38 brains from deceased adults across five groups: healthy adults aged 40 and younger, healthy older adults, individuals in early stages of cognitive decline, those diagnosed with Alzheimer’s disease, and super-agers.
The research included six super-ager brains donated by Northwestern’s SuperAging Program, which celebrated its 25th anniversary last year. The findings revealed that super-agers possessed twice as many new, or “immature,” neurons compared to healthy older adults, and two and a half times as many as individuals with Alzheimer’s disease.
Historically, it was believed that mammals were born with a fixed number of neurons. However, studies in the 1960s and 1970s demonstrated that adult neurogenesis occurs in rodents and primates. While evidence of this phenomenon in humans has been inconsistent, Lazarov’s research confirms that adult human brains are capable of generating new neurons, influenced by age and cognitive status.
Implications for Brain Health
The study’s insights suggest that super-agers exhibit a “resilience signature” in their brains, allowing them to cope with aging while maintaining cognitive function. Changes in two types of cells, astrocytes and CA1 neurons, were found to play a role in regulating memory and cognition within the aging hippocampus. Nevertheless, the authors acknowledged limitations in their study, such as a small sample size and inherent variability among human brain samples.
This groundbreaking research marks the first identification of a genetic difference between super-agers and typical older adults, according to the Northwestern SuperAging Program. Co-director Tamar Gefen noted, “There is no question that their hippocampi are completely different than other human beings’.” The program has uncovered various factors contributing to the exceptional health of these older individuals, including personality traits and neurological anomalies.
For instance, super-agers tend to identify as extroverts and possess more von Economo neurons, linked to social behavior. Gefen highlighted the significance of socialization for healthy aging, noting the detrimental effects of isolation. Additionally, super-agers often exhibit adaptability and openness to new experiences, along with low levels of neuroticism.
While normal aging leads to brain shrinkage, a study published in 2017 in the Journal of the American Medical Association found that super-agers experience this process at a slower rate than their peers. Research from 2021 published in the journal Cerebral Cortex indicated that super-agers resist neurofibrillary tangles, protein buildups associated with Alzheimer’s disease.
The immune system’s role in brain health remains a complex area of study. A 2019 study in Frontiers in Aging Neuroscience found that super-agers had fewer activated microglia, the brain’s immune cells, compared to individuals with dementia, and similar levels to those 30 to 40 years younger.
Despite the genetic advantages of super-agers, experts emphasize that maintaining cognitive health is achievable for everyone. Dr. Jennifer Pauldurai, medical director of the Inova Brain Health and Memory Disorders Program, encourages prioritizing cognitive well-being throughout adulthood. “If there is any opportunity for us to make that breakdown [of cognitive function] a little less intense, we should be talking about it,” she stated.
The research highlights the brain’s malleability and the importance of lifelong engagement in cognitive and physical activities. Pauldurai likened the brain to a lump of clay, which can be molded and nurtured to build neural pathways. Ignoring brain health can lead to deterioration akin to a neglected lump of clay, becoming difficult to work with.
Maintaining overall health is crucial for brain plasticity, with factors such as chronic illnesses or untreated mental trauma potentially impacting neuron growth. “I would rather talk about this than how I don’t have a cure to Alzheimer’s disease yet,” Pauldurai remarked.
Participants in the SuperAging Program, like Sel Yackley, an 86-year-old former journalist, attribute their cognitive resilience to active lifestyles. Yackley humorously noted her “super-ager duties,” which include staying physically active and socially connected, even if only through digital means. She emphasized the importance of engagement: “Don’t worry about the years. Just stay active, mentally and physically.”
This new research not only enhances understanding of the biological foundations of aging and cognition but also opens avenues for improving brain health strategies for individuals of all ages.
