Mental processing speed does not start to decline until age 60, according to analysis of over a million participants in a paper published in Nature Human Behaviour. These findings challenge previous assumptions that mental speed peaks at age 20.
As we age, it generally takes us longer to react to changes in our environment, or stimuli. This slowing of response time starts from the age of about 20, gradually continuing to increase as we get older.
Mischa von Krause and colleagues analyzed data from over one million participants who had taken part in an online experiment that measured their reaction times to a cognitive task. Participants had to categorize a selection of words and images that flashed up on a screen by pushing the correct key in response.
The authors found that — although response times did start to slow after age 20 — this could be attributed to increases in decision caution and to slower non-decisional processes, such as time taken to press the key. The mental process of making the decision as to the correct answer, however, did not start to slow down until age 60, after which it progressively declined.
The authors conclude that, despite a widespread belief in age-related slowdowns in mental speed, their findings highlight how for much of our lives, and during the timespan of a typical career, this is not likely to be the case. It also makes up part of a growing body of work that shows cognition isn’t necessarily doomed in old age.
In 2019, a team of Spanish researchers proved that new neurons are continually created even into the ninth decade of life, within a part of the brain called the dentate gyrus located within the hippocampus. The hippocampus is one of the primary reasons we can remember our experiences, as it’s the short-term storage house for memories.
It’s also one of the first regions to suffer from the onset of dementia and other neurodegenerative diseases like Alzheimer’s. Until recently, there was no evidence that adult hippocampal neurogenesis occurred in humans.
“Each part of the brain develops at a different speed. However, apart from the so-called neurogenic regions, as far as we know, other brain areas do not generate new neurons throughout lifetime,” said María Llorens-Martín, one of the authors at the time.
Multiple studies have shown that brain training games, learning new skills, and/or in conjunction with exercise, can all improve various aspects of cognitive ability and mass in people aged 60-85. This included increases in brain matter in the hippocampus and elsewhere from learning how to juggle, processing speeds and executive function from playing a video game, and increases in cortical sugar metabolism and episodic memory recollection from a combination of exercising and cognitive training programs.
All this can offer a better understanding of aging and how to prepare for it in order to do so gracefully, and to remain a valued and capable member of a community.