Most of us would welcome the prospect of an extended lifespan. But while entertaining such a prospect, we should also add two important caveats: good health in general and the retention of cognitive longevity.<\/p>\n
A small group of octogenarians\u2014informally known as superagers\u2014possess a memory<\/a> capacity equal to that of younger adults. Typically, an 80-year-old in this group demonstrates the memory powers of someone in their 50s or 60s, along with normal or above-normal performance in other cognitive domains. Until recently, brain research didn\u2019t offer much help in understanding such outliers and didn\u2019t present any neuroscientific explanation of how an 86-year-old could perform as well in memory as someone almost half their age. <\/p>\n Until recently, cognitive decline<\/a> was the prevailing leitmotif of our understanding of brain function in those 80 years of age or older. But in March, neuroscientists at the Northwestern University Mesulam Institute for Cognitive Neurology & Alzheimer\u2019s Disease announced, after 25 years of studying superagers, the discovery of a \u201cresilience<\/a> signature\u201d based on postmortem studies. They concentrated on hippocampal tissue in 38 individuals drawn from five groups: healthy young adults, older adults without impaired cognitive functioning, older adults with mild or early dementia<\/a>, older adults diagnosed with Alzheimer\u2019s disease, and finally, superagers. Superagers possessed about twice the number of immature neurons<\/a>, which retained the capability of additional maturation into adult brain cells within the hippocampal tissue. <\/p>\n In contrast, people who met the criteria for Alzheimer\u2019s disease possessed dramatically fewer neuroblasts (immature neurons) and neuronal precursor cells than were found in either healthy young or older adults. In addition, the Alzheimer’s disease cohort demonstrated an elevated number of neural<\/a> stem cells\u2014another neuron precursor, but one that was unable to differentiate into mature neurons. Only in the superagers did stem cells<\/a> retain the capacity to successfully differentiate into the immature neurons and neuroblasts responsible for neuronal development.<\/p>\n Delving into the Brains of Superagers <\/p>\n According to the researchers at the Mesulam Institute, the brains of superagers possess certain distinct features: The brains look younger with less cortical thinning, combined with thickening in the area of the anterior cingulate cortex (ACC), an important connection between the frontal cortex and the limbic system.<\/p>\n The anterior cingulate cortex is composed of highly specialized neurons known for their elongated shape and rapid signaling. These cells, known as Von Economo cells, play a commanding role in rapid response, emotional regulation<\/a>, decision making<\/a>, empathy, and socialization. The long, spindly body of the Von Economo cell facilitates rapid transmission by forming the equivalent of a \u201chigh speed highway\u201d passing within the anterior cingulate cortex (ACC) and the fronto-insular cortex (FIC). Among superagers, these Von Economo cells reach a higher density than in anyone of comparable age.<\/p>\n A second distinction in most superager brains is a much reduced amyloid plaque and tau tangles burden\u2014the two abnormal cell types found to accumulate in Alzheimer\u2019s disease. But even within the brains of those superagers who showed the expected-for-age numbers of plaques and tangles, the practical consequences were much diminished: The affected person remained much more cognitively intact. Think of these resilient brains of the superagers as demonstrating increased plasticity, thus accounting for the brain\u2019s retention of memories.<\/p>\n Traits commonly observed among superagers and cognitively resistant very old adults include reduced chronic stress<\/a>, increased adaptability, increased social embeddedness with many friends and acquaintances, and emotional stability<\/a>. More than likely, additional traits will be discovered, but at this point, our knowledge of relevant behavioral and personality<\/a> traits is limited based on the rarity of retained high cognitive functioning in the very elderly.<\/p>\n Although at this point no agreement exists among experts concerning which of these important contributors may exert the most powerful effect, my own observations lead me to emphasize the importance of long-term, intense intellectual involvement in what I term \u201ccognitive hobbies.\u201d <\/p>\n I\u2019m thinking now of a man I met on an Egyptian tour several years ago. He did not fit the stereotype of a scholar; his education<\/a> was limited to a few years beyond college, and his occupation was very different from the usual mix of academics, lawyers, and doctors found on the typical study tour. He had started out as a construction worker and had risen over the years to the manager of his own construction company. Yet after we had shared a few Q&A sessions, his cognitive sharpness was obvious to all the members of the tour. He knew more about Egypt and Egyptology than anybody, with the exception of the tour leader<\/a>. <\/p>\n Curious, I asked him during a break how and why he had learned so much about Egypt. He still remembered the lesson about ancient Egypt his teacher had given to his fifth-grade class. This had ignited a lifetime effort to learn more and more. Over the next 40 years, he had collected and read numerous books on Egypt, attended lectures about various aspects of Egyptian culture, and joined tours about Egypt, such as the one we were then participating in.<\/p>\n In essence, he had developed what I call a \u201cmagnificent obsession\u201d\u2014an intense intellectual interest in a specific subject accompanied by long-term efforts to learn everything possible about it. Essentially, his knowledge of Egyptian history corresponded to a massive enlargement of his store of crystallized knowledge, with each new fact built on something learned earlier. New knowledge led to new questions, which he addressed by reading additional books and attending lectures and tours.<\/p>\n