Playing brain-training video games may help reverse the natural decline in cognitive abilities among older people, according to scientists.

They found that 60-year-olds who played a custom-designed video game for 12 hours over the course of a month improved their multitasking abilities to levels better than those achieved by 20-year-olds playing the game for the first time. The subjects retained those improvements six months later.

"Through challenging your brain, you can drive plasticity and improve its function," said Adam Gazzaley of the University of California, San Francisco. His team's findings suggest the ageing brain is more "plastic" than previously thought, meaning it retains a greater ability to reshape itself in response to the environment and could therefore be improved with properly designed games.

In their experiment, published on Wednesday in Nature, Gazzaley's team asked participants to play a game the researchers had designed called "NeuroRacer" which involved driving a car along a hilly, winding road. At the same time, they had to press a button whenever they noticed a target sign – a green circle, say – appear at the top of the screen. Another version of the game involved just pressing buttons when the signs turned up on screen, without having to drive the car.

The researchers measured the "multitasking cost" for the participants as the change in accuracy from doing the sign task by itself, to doing the sign task and driving the car at the same time. A -50% cost, for example, meant the participant had a 50% reduction in their accuracy as a result of having to multitask.

Gazzaley first assessed groups of healthy people at different ages and found, unsurprisingly, that multitasking abilities declined with each extra decade of life from the age of 20 to 80: 20-year-olds had an average multitasking cost of around -25%, 30-year-olds had an average cost of around -40% and 70-year-olds had a multitasking cost of more than -65%.

The subjects, aged 60 and 85, played the game for an hour three times a week over the course of a month. As a result, the team found their average multitasking cost dropped dramatically.

"They went from a 65% cost to a 16% cost," said Gazzaley. "These games exceeded both that of an active control group as well as the non-contact control and they also exceeded levels attained by 20-year-olds who only played the game a single time." The improvement was still there six months later.

Cognitive tests carried out by the researchers before and after the sessions with NeuroRacer also revealed improvements in their attention and working memory, areas of cognition that were not directly targeted by the video game.

Peter Etchells, a psychologist at Bath Spa University who studies the effects of computer games on the brain, said that Gazzaley's work was "a great example of how video games tailored to specific populations can be used to improve mental health. We hear a lot about how video games might be bad for us, but it's not really a simple, black-and-white story."

Robert Howard of the Institute of Psychiatry at Kings College London said that reports of ways to deal with cognitive decline tended to generate a great deal of interest in older people and those who worry that they might be in the early stages of disorders such as Alzheimer's disease. But he added: "We are still a very long way from being able to recommend cognitive training as a preventative or treatment measure."

Gazzaley said his findings were not directly comparable to existing commercial video games and he was keen for people not to overinterpret the results.

"One thing I'm cautious about is that it's not blown out of proportion in that the conclusion from this is that video games are a panacea for all that ails us," he said. "The devil's in the details and this was a very carefully constructed game that was targeted to a known neural deficit and a population."

But he said that the results could be extrapolated to other situations. It was a reasonable hypothesis, he said, to speculate that training with video games might help people of all ages keep up their cognitive reserves and that it might even be useful for people with the many neurological and psychiatric conditions that also affect cognitive function.

Tom Kirkwood, director of the Institute for Ageing and Health at Newcastle University, said training with video games is known to result in improved cognitive performance. "It would be surprising indeed if this was not underpinned by measurable changes in neural activity," he said.

"It would also be surprising if training effects did not persist for a while. Just think of all those music teachers who would be out of jobs if this were not the case. In this connection, it is a bit surprising that the authors did not compare the benefits and persistence of training effects in different age groups. It would have been especially interesting to know whether older adults were significantly less trainable than younger adults, or if the results were relatively comparable."

Kirkwood added that, in experiments of this kind, it was tough to control for the benefit that came from reinforcement of self-belief when engaging with a new challenge. "Those in the 'multi-tasking' group will inevitably have been aware that they were doing something quite demanding which might have generated wider psychological and cognitive benefits."