Mental speed stays high until 60, analysis of 1million people reveals

Mental power only fades in your 60s: Speed at which your brain processes information does NOT peak at end of teenage years, study finds

• A study of 1.2million people found mental speed does not fall until the age of 60
• Findings challenge assumption mental speed peaks in young adulthood
• Researchers say slower responses due to more caution around decision-making

People don’t need to worry about slowing down mentally until they are at least 60, a major study suggests.

Researchers in Germany, who tracked 1.2million people, believe they’ve dispelled the theory that mental speed peaks at 20.  

They say thinking speed, how quickly someone reaches a correct answer, increases through your twenties before plateauing when you hit 60.

This suggests brain power doesn’t slow down until long after the body does.  

‘Our results challenge the widespread notion of an age-related slowdown in mental speed,’ the experts said. 

The graphs show results from cognitive tests taken by 1.2million people that were analysed by researchers at Heidelberg University. It shows that average response times (top left) to questions in tests dropped after the age of 20. But mental speed (top right graph) increased between the age of 10 and 30 and then remained stable until the age of 60. Researchers said the increase in average response time was explained due to increases in decision caution (bottom left) and non-decision time (bottom right), rather than a drop in mental speed

Previous studies that suggested middle-aged people are slower thinkers were based on the average response times to log an answer, which can include other mental and physical processes. 

In the new study, Heidelberg University researchers used a different calculation that allowed them to extract mental speed from the volunteers’ response time. 

They drew on mental test results of roughly 1.2million people aged 10 to 80 between 2016 and 2018.

Participants classified words and images that flashed onto a screen into one of two categories, such as good or bad, by pushing buttons. 

The pooled results, published in the journal Nature Human Behaviour, found mental speed increased between the ages of 10 and 30 and then remained stable until the age of 60. 

The researchers said this signals ‘little age-related difference’ in mental speed during middle age.

It also dispels the assumption that older adults are just slow thinkers, which can have ‘notable consequences in work life’. 

However, after hitting 80, mental speed does quickly deteriorate, the team said. This is due to the natural ageing process, which shrinks the brain. 

But they found that average response time when completing the task did fall sharply after the age of 20, mirroring findings from earlier studies.

The researchers put this down to decision caution, the amount of information taken in before reaching a decision, which dropped between the ages of 10 and 18, before increasing for the rest of people’s lives.

This suggests people have the least inhibitions at 18, when they are ‘most willing to trade off accuracy for speed’, they said.

The team also pointed to non-decision response time, such as the time taken to process the words in the task and push the button. 

This increased from the age of 15 to 80, which the researchers provides a second explanation for why previous studies found reaction time increased with age.

The researchers said: ‘Our analyses suggest that the average levels of mental speed remain roughly stable across all of middle adulthood, with only slight decreases from age 50 on.’

This ‘surprising finding remains hidden’ if average response time is the only element measured, because this does not take into account the time taken up by decision caution and other brain processes, they said.

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