A large-scale study has shown that brain training can help some older people keep up with those in their 20s.
This research has potential for the ageing population because it shows it's possible to improve mental performance through training.
Researchers in Newcastle and California used the brain-training app Lumosity to examine people's ability to switch between two tasks.
The app's Ebb and Flow game was used to assess how practice improved the performance of more than 1000 people.
Professor Frini Karayanidis, of the Hunter Medical Research Institute's brain program, said older people performed worse on task-switching than young adults.
The older people also showed a slower rate of improvement with practice.
However, the gap between young and old reduced with practice.
The more practice, the greater the improvement, regardless of age.
Professor Karayanidis said the evidence showed that doing a lot of brain training can make people good at it.
Some companies have made overstated claims about what their apps can do.
But researchers don't yet know if brain training makes people smarter and generally better at real-world activities, like work projects or learning a language, for example.
The study showed that older people who completed at least 60 brain-training sessions did not reach the level of performance of younger people.
However, a promising finding emerged when researchers examined older people who over-practiced at brain training.
A proportion of people who did thousands of sessions did reach the level of a young person.
"Some people, with substantial practice, can reverse the age-related decline in this task," said Professor Karayanidis, of the University of Newcastle's school of psychology.
"We don't know why some did and some didn't. That's the next step."
The researchers - from the universities of Newcastle and California - now aim to examine what makes older people particularly responsive to a large amount of brain training.
They also aim to determine whether such training can maintain and improve real-world skills, such as safe driving.
In future, the research could aid the advance of personalised medicine in the area of cognitive decline.
For example, customised programs could help people reverse the rate of decline in specific cognitive skills. It could also help people maintain the cognitive skills they have, or pre-empt decline.
At the moment, modern medicine does not have proven methods to pre-empt cognitive decline.