What makes 'superager' brains more resistant to aging?

Medical News Today

4 hours ago

Research is ongoing about what components contribute to healthier brains as people age. Recent research identified some unique brain features of 'superagers,' people at least 80 years old who perform cognitively similarly to people decades younger. The research also identified that superagers tended to be more sociable than their peers. More research into superagers could lead to interventions that help protect cognition.Some people have better cognitive function than others as they age, and this is an area of scientific study.A study recently published in Alzheimer's & Dementia details the unique features of a group of superagers. These people meet certain word recall cognitive criteria in later life.The research suggests that superagers are very sociable and also identified unique brain characteristics of this group, such as higher levels of von Economo neurons, also known as 'spindle neurons.' These unique brain cells appear to be involved in emotional processing and social cognition.What makes a person a 'superager'?This research looked at 'the first 25 years of the Northwestern University SuperAging Program.' This program seeks to see if it's possible to avoid the decline in brain capacity that comes with age and the possible biological phenotype — or observable traits — related to this avoidance. The paper explains that the term superaging was developed by the Northwestern Alzheimer's Disease Research Center (ADRC).Superagers are people who are 80 years old or older who meet a certain score on a test called the Rey Auditory Verbal Learning Test. Superagers' scores are similar to those of people between the ages of 56 and 66. Superagers were also at least average for age in other areas of cognitive function. Right now, there are 133 active participants in the Northwestern ADRC Clinical Core. Researchers have conducted 77 autopsies to look at the brain features of deceased participants, based on brain donation. Researchers did not pinpoint a lifestyle linked to superaging. Some participants followed a healthy lifestyle while others followed less healthy patterns.Superagers also appeared to have similar medical problems to their neurotypical peers. However, superagers were noted as being sociable, enjoying extracurricular activities, and endorsing extraversion. They were also more likely to rate their relationships positively than their peers.Using neuroimaging, researchers found that superagers did not display cortical thinning, a thinning in the outer layer of the brain, that nonsuperagers experienced.While there is more research needed to see if superagers start with larger brains, researchers suggest that cortical thinning happens more slowly in superagers.They also identified an area of the brain called the anterior cingulate that had more cortical thickness compared to younger neurotypical participants. This area of the brain is involved in things like emotion and social networking. In the anterior cingulate gyrus, there were also higher levels of nerve cells called von Economo neurons. This was even in comparison to younger individuals. Researchers think that superagers might have this higher nerve density from birth. Researchers also looked for neurofibrillary tangles, a protein buildup in neurons that can be present in Alzheimer's disease as well as in normal aging.Overall, researchers found that superagers had fewer neurofibrillary problems than their peers. For example, in superagers, they observed fewer neurofibrillary tangles in the rhinal cortices, an area of the brain. Superagers' brains may be more resistant to cognitive declineResearchers concluded that 'there are at least two pathways to the maintenance of youthful memory capacity in old brains.' They suggest that this type of brain could resist the start of neurofibrillary pathology and be resilient to the cognitive effects of neurofibrillary pathology.Furthermore, they observed that superagers had another type of neuron that was bigger. This difference may make a specific brain pathway resist changes like neurofibrillary degeneration.Or it could be a reactionary change leading to resilience. When looking at plasma biomarkers, superagers also had lower levels of something called p-tau181, which researchers note was consistent with the lower levels of neurofibrillary degeneration. The findings further support that superagers have enhanced functionality of a component of the brain called the cortical cholinergic system at multiple levels. This system can be affected both in Alzheimer's disease and normal aging. Finally, researchers observed differences in the microglia of superagers. Microglia are cells in the brain that help control the microenvironment of the central nervous system.In superagers, there were fewer activated microglia in the white matter, something that happens in physiological aging. Preliminary findings suggest that microglia in superagers may have distinct features. The authors note the need for more research in this area. In their publication, the authors also included a case study of one superager who was highly independent until she experienced a stroke near the end of her life.When observing her brain, researchers observed certain characteristics. For example, the amygdala and hippocampus areas of the brain were similar to those of a younger person. They also observed features like 'low density of neurofibrillary tangles and pretangles' in the postmortem examination. Kaushik Govindaraju, DO, from Medical Offices of Manhattan and contributor to Labfinder, who was not involved in the study noted the following about the research to Medical News Today: 'We have thought that mental decline with aging is inevitable and even expected/anticipated. We marvel at elderly people who have good memories because for as long as humanity has existed, we have been told and have seen that this is not the biological norm. This research may push back against this in an unprecedented way.'Study limitations and continued researchThis research provides more information on a possible superaging phenotype, but has limitations. For one thing, it examined a fairly small number of participants, and recruitment methods could have impacted the study sample. This particular paper also did not release information on certain components, such as the gender breakdown of the group or ethnicity. This research is ongoing, and this paper noted components of the first 25 years of the research. Some reported data was also based on preliminary findings, like the biomarker data, so more research is needed. Certain eligibility requirements, such as being able to attend in-person visits in Chicago, may also affect the research. Methods of data collection may also be important to note, such as the use of surveys. Researchers also pointed out that current methods for staging of neurofibrillary changes might need to be reevaluated, since it does not reflect the presence of undamaged neurons.They show one superager who had some neurofibrillary degeneration but also a higher level of normal neurons, which might not be present in neurotypical peers who have the same amount of neurofibrillary degeneration. More research is required to see what features are present from birth in superagers, as well as how the results may apply to the general population. More research into the distinct differences in superagers' brains and why they are present may also be helpful.What can we learn from superagers?This research could lead to developing strategies to help 'typical' agers. Alexandra Touroutoglou, MSc, PhD, an assistant professor of neurology at Harvard Medical School, and director of Imaging Operations at Frontotemporal Disorders Unit at Massachusetts General Hospital, who was not involved in the recent research, noted the following general benefits of studying people who age well: 'Superagers are exciting because they show that age-related memory decline is not necessarily inevitable. So much of aging research is focused on looking at pathology and disorder, trying to work backwards to what went wrong. But there are things we can learn from those who age exceptionally well. Studying those people who age best could point the way to new treatments, either in terms of interventions or lifestyle changes, that could prolong cognitive health for all the rest of us who age in more typical ways.'Emily K. Hurst, DO, AOA board-certified in Critical Care Medicine, Internal Medicine, and Hospice and Palliative Care Medicine, likewise not involved in the current study, commented that 'identifying superagers and continuing to study their unique characteristics both biologically and environmentally, can determine how the modifiable changes may be translated to others in their quest to deter cognitive decline.''This will be a game changer in avoiding senescence,' said Hurst. 'I hope this article serves to help our society recognize and elevate the value many of those in our community can contribute in years long past retirement, and help medical professionals see our patients in their ability instead of their numerical age.'