SuperAgers' Brains Reveal Secrets to Sustained Cognitive Function
A recent study highlights remarkable findings about "SuperAgers"—individuals in their 80s and 90s who maintain cognitive abilities comparable to people decades younger. These exceptional individuals produce a greater number of new neurons in the hippocampus, a brain region central to memory. The research also points to specific cellular support systems and unique physiological characteristics within their brains that may contribute to their sustained cognitive function, offering new insights into brain plasticity and the aging process.
Key Findings: Increased Neurogenesis
The study, published in the journal Nature, made a groundbreaking discovery regarding neuron production in SuperAgers.
SuperAgers produce twice as many immature neurons compared to cognitively healthy older adults and 2.5 times more than individuals with Alzheimer's disease.
Furthermore, the brains of SuperAgers contained more newly developed neurons than those of adults in their 30s and 40s. Researchers noted that this suggests a molecular capacity in SuperAgers that supports higher cognitive performance and increased neurogenesis—the birth and survival of new neurons.
A SuperAger is defined as an individual aged 80 or older who demonstrates the memory capacity of someone 20 to 30 years younger, typically assessed through delayed word recall tests. Six SuperAger brains for the study were provided by Northwestern's SuperAging Program, which has been studying these unique individuals for 25 years.
Cellular Mechanisms and Brain Structures
The research delved into specific brain cells and their pivotal roles in SuperAger memory retention.
Essential Brain Cells
- Astrocytes: These cells, more numerous than neurons, play a crucial role in regulating blood flow to the brain and promoting synapse formation—processes fundamental to brain function, learning, and memory.
- CA1 Neurons: Essential for memory consolidation and retrieval, these neurons are notably among the first affected by tau tangles in Alzheimer's disease.
In SuperAgers, astrocytes and CA1 neurons were observed to robustly support the hippocampus by enhancing synapse signaling between neurons. This intricate coordination creates an enriched environment that promotes the function of immature neurons, CA1 circuits, and astrocytes.
Unique Structural Characteristics
Previous research on SuperAgers has identified several additional distinguishing characteristics:
- A thicker cingulate cortex, an area associated with attention, motivation, and cognitive engagement, compared to people in their 50s and 60s.
- Three times fewer tau tangles in the hippocampus, a pathological hallmark of Alzheimer's disease.
- Larger neurons in the entorhinal cortex, an area typically affected early by Alzheimer's, surpassing the size of neurons found in much younger individuals.
- Resistance to neurofibrillary (tau) tangles and fewer activated microglia (brain immune cells) compared to individuals with dementia, with levels similar to those seen in people 30 to 40 years younger.
- A higher number of von Economo neurons, which are linked to social behavior.
Methodology
Senior author Orly Lazarov indicated that previous research on neurogenesis in humans had been ambiguous due to measurement constraints. This study utilized multiomic single-cell sequencing to measure new neuron birth across five categories of donor brains: SuperAgers, healthy young adults, older adults without cognitive decline, older adults with early dementia, and older adults with Alzheimer's disease.
This advanced technique allowed for the precise identification of specific brain cells critical for memory and cognition within the aging hippocampus.
The study acknowledged a small sample size, and variability among human brain samples is a common factor in such research.
Genetic Factors and Lifestyle Considerations
While researchers, including co-director Dr. Tamar Gefen of the Northwestern SuperAging Program, note that SuperAgers may possess certain genetic advantages, experts emphasize that lifestyle factors can also significantly contribute to brain health and may prevent cognitive decline.
Recommendations for supporting brain health include:
- Physical Activity: Maintaining regular physical activity throughout life.
- Cognitive Engagement: Actively using the brain and remaining cognitively fit and engaged.
- Holistic Health Management: Addressing chronic illnesses, reducing stress, optimizing sleep, and managing vascular risk factors.
- Mental Well-being: Addressing mental trauma.
Dr. Richard Isaacson, an Alzheimer's prevention researcher not involved in the study, highlighted that lifestyle changes can promote brain area growth, including the hippocampus, and reduce signs of Alzheimer's such as tau tangles and amyloid plaques. Dr. Jennifer Pauldurai, medical director of the Inova Brain Health and Memory Disorders Program, suggests that the brain is adaptable and that individuals can build neural pathways. Sel Yackley, an 86-year-old SuperAging Program participant and former journalist, advises others to maintain both mental and physical activity and engagement.