If you're in your late 20s or older, you're not as sharp as you used to be, suggests a study of gamers playing the popular video game Starcraft 2.

The study analyzed the way 3,305 people, aged 16 to 44, played the game against a single random opponent of similar skill, in order to measure the gamers' cognitive motor performance. Cognitive motor performance is how quickly your brain reacts to things happening around you, allowing you to act during tasks such as driving.

Starcraft is like high-speed chess. - Joe Thompson, psychology researcher

The analysis revealed exactly when advancing age starts to take its toll on brain performance – at the tender age of 24 years.

The results were published late last week in the journal PLOS ONE.

Joe Thompson, lead author of the study, said he was surprised by how early the decline started and how big the age effect was, even among those in their 30s.

"If you're 39, competing against a 24-year-old and you're both in the otherwise same level of skill," Thompson said, "the effect of age is expected to offset a great deal of your learning."

Visitors play Starcraft 2 at a gaming conference in Germany. The popular game has a well-established ranking system, professional players and televised games. (Ina Fassbender/Reuters)

Starcraft 2 is a popular strategy game, similar in concept to Risk, where players compete to build armies and conquer a science fictional world. Unlike Risk, however, players don't take turns.

"Starcraft is like high-speed chess," said Thompson, a PhD student who plays the game himself. "You simply can make as many moves as you want, as fast as you can go."

Players can't see the whole "world" at once, as they mine resources needed to build up their armies, as they attack their opponents, and as they defend against opponents' attacks, they need to quickly move their screen around from one part of the world to another.

"That gives you a sense of how fast the game is and how big an advantage speed is."

The game has become a popular competitive e-sport, with a well-established ranking system, professional players and televised games, especially in South Korea.

While many high-performance athletes start to show age-related declines at a young age, those are often attributed to physical as opposed to brain aging.

With Starcraft, Thompson said, the physical demands are minimal, as the game is played with a keyboard and mouse.

"The speed seems to be coming from the brain."

Similar to real-world situations

While previous lab tests have shown faster reaction times for simple individual tasks, it was never clear how much relevance those had to complex, real-world tasks such as driving.

Thompson noted that Starcraft is complex and quite similar to real-life tasks such as managing 911 calls at an emergency dispatch centre, so the findings may be directly relevant.

However, game performance was much easier to analyze than many real-life situations because the game generates detailed logs of every move. In a way, Thompson said, the study is a good demonstration of what kinds of insights can be gleaned from the "cool data sets" generated by our digital lives.

While the results of the study may sound surprising and alarming, the fact that we don't really notice the decline in our 20s and 30s is good news, Thompson suggests.

"I think we're adapting without knowing it," he added. "A lot of us are still able to maintain our skills."

In fact, that held true for older Starcraft players also, when only their score was taken into account.

"We had a lot of people performing at a level higher than their speed would otherwise suggest."

It appeared the older players compensated for their slower speed by making better use of features such as shortcuts and by using simpler strategies.

While the study yielded some interesting results, Thompson noted that there were some gaps in the findings.

"The most important thing is we can't talk about women," he said, noting that only 20 out of the 3,000 participants were female.

Participants were recruited on Starcraft community websites, so the researchers had trouble getting players with the full range of skill levels, particularly weaker players. Thompson said that generally, the study would like more participants to build on its results so far.