At what age does cognition peak in adulthood - somewhere between the speed of youth and wisdom of age? Can we even say there is a prime time for brain fitness?
At a glance
- A better understanding of the brain’s ability to adapt to change has helped reveal a more positive outlook on our cognitive performance as we age.
- Cognitive skills peak at different times: speed in processing information peaks at 18-19 years, but vocabulary skills can peak at 60-70.
- These new insights play a key role in valuing and developing neurodiversity in age-diverse teams.
At what age do we peak mentally? Do you think you are at your sharpest now, or are you on a downward slide?
It’s a question some may want to avoid for fear of feeding age discrimination in the workplace. However, it’s highly relevant to service professionals, whose brains are arguably the most important organ affecting their performance.
With our ability to proficiently learn a new language declining from the age of about 17.5 years, according to a large study published in the journal Cognition, and our mental speed slowing after a peak in our early 20s, the outlook for our cognitive trajectory might seem grim.
However, scientists are revealing a more nuanced and positive picture of how the brain changes during adulthood, thanks in part to a growing understanding of neuroplasticity – the brain’s ability to change itself in response to the environment.
Researchers from the Massachusetts Institute of Technology (MIT), who gathered data from nearly 50,000 people, found that each cognitive skill they tested peaked at a different age. For example, raw speed in processing information peaked at about age 18 or 19, then immediately started to decline. Short-term memory continued to improve until about age 25, when it levelled off and then began to drop at about age 35.
Meanwhile, a person’s ability to evaluate other people’s emotional states peaked much later, in their 40s or 50s. When it came to vocabulary, which serves as a measure of “crystallised intelligence” – the accumulation of facts and knowledge – the data showed a peak for people in their late 60s and 70s.
“At any given age, you’re getting better at some things, getting worse at others, and plateauing at other skills,” says Joshua Hartshorne, one of the paper’s authors and assistant professor in psychology at the research university Boston College. “There’s probably not one age at which you’re peaking on most things.”
This should serve as a leveller for age diverse teams and workplaces, where age related negative stereotypes about cognition, such as “They won’t cope with the CRM or data analytics”, or “They’ll take too long to onboard” are alive and well.
Performance adviser Rob Hartnett commonly hears such comments about mature-aged employees in his consulting work with intergenerational teams, including in the finance sector. “Baby boomers often talk about millennials as being unable to concentrate and stick with things when they get tough, and therefore question hiring them.”
Clearly, dismantling negative stereotypes is key to seeing people’s true worth, but let’s not fudge the facts in the process. What is really true about how the brain changes with age in healthy adults?
Dr Nicola Gates, clinical neuropsychologist and author of A Brain For Life and The Feel Good Guide to Menopause, summarises what the research tells us. There is general consensus that processing speed – how quickly the brain can process information and then provide a response – declines soon after our mid-20s.
The executive functions of the brain, which include the higher order attention and thinking skills such as planning, prioritising, problem solving and abstraction, also start to decline in the process of normal ageing and especially in later life. This means that focusing in a loud, busy environment, sustaining attention on a difficult task or multitasking, where you repeatedly switch from one task to another, might become more difficult or take longer.
Certain types of memory also change. While long term memory – remembering information – and procedural memory – remembering how to drive, for example – remain relatively stable, acquiring new information and retrieving specific words and people’s names can falter. In her practice, Gates will often see people in their 60s who notice these memory changes.
As for putting a number on the rate of cognitive change at specific ages, Gates is reluctant due to the many factors that have a powerful influence on ageing and the brain, such as sleep, stress, social connection, mental challenge, diet, physical activity and purpose in life.
Mental stimulation, for example, could add as much as a decade or two to your mental cognitive peak, at least for some abilities. Data collected by MIT researchers in 2015 found that vocabulary peaked in people’s late 60s and 70s. Data collected two decades earlier found a vocabulary peak in people’s late 40s.
The researchers speculated that this may be a result of better education, more people having jobs that require a lot of reading, and more opportunities for intellectual stimulation for older people.
This explanation concurs with other research that shows that working for longer protects cognition, as does higher educational attainment.
Neuroplasticity can also work against brain function. “There is evidence of diminished sustained attention spans in younger people,” says Gates, who attributes this to exposing young minds to a constant stream of highly entertaining information, distracting notifications and alluring clickbait.
The young, the old and in-betweens all have mental strengths, vulnerabilities and unique cognitive signatures imprinted into their brains by life experience. How can organisations make the most of this? By valuing the neurodiversity found in age-diverse teams, says Gates.
“Many workplaces focus to an inappropriate extent on speed and efficiency, which is not appropriate for all work types,” says Gates. “Complex decisions, for example, require considered reflection. Workplaces need both the speed of youth and the experience or wisdom of age, so it makes good business sense to value them equally.”
Hartnett encourages managers to get to know the strengths of their people, including their cognitive strengths, and play to them. “Understand what each person brings to the table, then empower them with a project that plays to their strengths. Buddy them up with someone with quite different strengths to encourage ongoing learning.”
If managers and colleagues challenge limiting mindsets, appreciate neurodiversity and seek out opportunities for collaboration, they are likely to discover a much broader cognitive palette than the stereotypical slow older worker or impatient young upstart.
Age does not define us
Staff at the Cootamundra based business law firm JMA Legal span almost three generations, from the 20-year-old receptionist to 76-year-old director Jim Main.
Thirty-eight-year-old co-director Michaela Schmidt works closely with Main – their clients consider them a team. They share their workload according to strengths, with Main designing the solutions and Schmidt using her attention to detail to implement them. They don’t, however, attribute their strengths to age.
“I think my brain works better now than it did when I was decades younger,” says Main. “I can analyse things better and I honestly haven’t noticed a reduction in mental speed."
Schmidt agrees. “I’ve worked with Jim for eight years now and haven’t noticed any difference. Jim does forget people’s names, but my memory for names is equally as bad due to having so much on our minds: the workload, the time pressures and stress.
“The intergenerational age stereotypes don’t really apply to us. Jim was the first one to move towards electronic filing and is right up with the technology. Plus, he’s fitter than most of us.”
Main walks daily for an hour and does another hour of exercise most days. His brain fitness may also be boosted by two professional development sessions a week and reduced stress because he is confident and trusts his own judgement. There is also social connection; Main loves his work and his colleagues.
How long does Main plan to keep working? “As long as I like, unless I’m told I can’t come to work in my pyjamas.”
Physical fitness promotes brain fitness
Physical activity significantly slows age-related cognitive decline. One study, for example, found that moderate exercise three times a week for 40 minutes for a year reversed age-related shrinkage of the hypothalamus by 2 per cent – effectively reversing age-related loss by one to two years. The change in brain structure was accompanied by an improvement in spatial memory, which helps you remember where you put your car keys or filed a document.
Create a brain-friendly environment for all ages
Remember that life experience and choices have a big impact on our thinking abilities, so beware of assumptions about someone’s abilities based on age alone.
Identify team members’ different strengths and play to them.
Build psychological safety so you can explore cognitive vulnerabilities and find ways to strengthen or compensate for them. If a worker is slow in processing certain information, outsource it to a computer or allow more time. If sustaining focused attention is a problem, allocate dedicated thinking time.
Create a culture that encourages employees of all ages to keep learning new skills.
Encourage generations to come together to collaborate on projects, so they can benefit from each other’s cognitive strengths and perspectives.
Check your own age related bias and beliefs – especially the self-limiting ones. They can prove self-fulfilling.
Identify quiet places where workers can go to concentrate. This is good for people of all ages.
Discourage multitasking – it reduces speed and accuracy for workers of all ages.
Allow more time for information processing, particularly when making important decisions. This could involve sending out information before a meeting, or allowing time to come back later, after some reflection.