Here’s what neuroscientists know about the brains of older people who age without losing any of their cognitive abilities.

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Atlantico: Forgetfulness, confused thoughts… Very often, cognitive abilities deteriorate with age. However, some people, mysteriously called “super-old”, seem to have an easier time coping with the ravages of time. Who are these “super elders”? Are there any significant differences in their lifestyle or habits compared to other people their age?

André Niellon: To think that general cognitive decline is inevitable with age is actually somewhat simplistic. For at least two reasons. First, because if it is true that some aspects of cognition are clearly sensitive to aging, and this can be understood by measuring cognitive ability as a function of the processing speed required for reasoning, then what we call “working memory” is particularly important for implementation of this process. – the so-called “executive” functions or the so-called “episodic memory”, other aspects of cognitive functions, in contrast, do not seem to be significantly affected with age; such as verbal skills, so-called “procedural” skills or even semantic memory regarding the meaning of words or even skills related to mental calculations, for example. Then, and this is the second reason why, in my opinion, it is too simplistic to assume that cognitive decline with age is inevitable, because not all people suffer in the same way. It is in this context that the concept you evoke of these “super-old” people, who, according to recent research, have cognitive abilities at around age 80 equivalent to those of people in their 20s and 30s less has emerged. , which may represent about 5% of the elderly population without neurological or psychiatric disorders.

Numerous studies have been devoted to them for several decades, since the cognitive abilities of these people are remarkable, leading to the conclusion that while skills related to knowledge and acquired experience are generally preserved with age, skills related to reasoning are especially preserved in these “super-elderly” people. All the work is aimed at understanding what might explain these people’s surprising resistance to aging compared to others. At this stage, the question remains open and it turns out that a priori neither lifestyle, nor nutrition, nor education can really explain this special resistance to the effects of time, unless these subjects have particularly developed social relationships and remain very physically active and are detrimental to their mental health, assessed in terms of anxiety and depression, which is much less than that of subjects demonstrating “normal” cognitive function in relation to their age. But at this stage, nothing definitive has been achieved, and research continues, on the one hand, at the genetic level, on the other hand, casting doubt on the possible features of the organization of the brain.

The study, published in the journal Neuroscience, helps shed light on what makes super-elderly people so special, highlighting differences in their brain structure. What are we talking about ? What causes these differences?

You are referring to a recent study by a group of Spanish researchers who studied the cerebral organization of these “super-aged” people using MRI to see if the structure of the brain itself was preserved compared to the brain structure of people showing aging. considered “normal”. Overall, the main result of this study is to show that, if we are interested in the evolution of brain structure over a 5-year period, starting at age 75, structural changes perceived in terms of volume of gray matter and white matter were characterized by a form of brain conservation over time in the “super-aged”, while in other subjects brain volume changed significantly over the same period of time. These data were associated with the special cognitive abilities of “super-aged” people.

Interestingly, however, when researchers take a closer look at white matter, which is the bundles of fibers that connect different areas of the brain together, it turns out that these brain connections are especially preserved in the areas represented by the forebrain, which we call on the one hand, the frontal lobe. involved in cognitive functions, or even the cingulate cortex, with no significant differences in areas involved in memory and attention processes, especially the hippocampus, relative to what is generally believed to be these structures more sensitive to aging. than the rest of the brain. However, other studies, this time focusing on the gray matter where neurons are located, tend to show that, in contrast, the super-old have relative sparing of these areas involved in memory processes. suggesting better control of these processes by the prefrontal cortex. But at this stage, no explanation has been provided for the origin of these structural preservations of the brain in relation to old age.

Are there reflexes that we need to use to “preserve” our brains as we age?

Since it has not been possible to identify a determinant of these mechanisms in terms of demographic factors, lifestyle or even genetics (at this stage) that could explain the special cognitive abilities of the “super-elderly”, it is difficult to offer plausible recipes. reduce the impact of aging on behavior. We will therefore adhere to the usual considerations that a healthy lifestyle, including diets designed to reduce the effects of obesity or even diabetes and cardiovascular disease, as well as regular physical activity and sustainable, maintaining strong social connections, clearly have a positive impact on the consequences aging.

Most research on aging and memory focuses on people who develop dementia later in life. Should research focus on healthy older adults?

In principle, you are right, but one does not exclude the other. From a public health perspective, priority is rightfully given to Alzheimer’s disease research, given the burden that dementia poses to our society. But it is interesting to note that several studies have noted that “super seniors” appear to be less likely to develop Alzheimer’s disease than their less cognitively advantaged peers. Perhaps this is an area of ​​research we should invest in to try to understand why these people are particularly resistant to developing dementia.