Playing online games which exercise reasoning and memory skills could have major benefits for older people, a wide-scale study has found.
Researchers at King's College London discovered that mental exercises, or "brain training", can improve people's everyday lives, helping with tasks like using public transport, shopping, cooking and managing personal finances.
Almost 7,000 people over the age of 50 were recruited from the public through the BBC, Alzheimer's Society and the Medical Research Council to take part in the six-month experiment.
Some participants were encouraged to play a 10-minute brain-training package as often as they wished.
The package comprised three reasoning tasks, such as balancing weights on a see-saw, and three problem-solving tasks, such as putting numbered tiles in numerical order.
Volunteers completed cognitive tests, including assessments of grammatical reasoning and memory, before the study began and again after six weeks, three months and six months.
Those over 60 also carried out tests of daily living skills, such as using the telephone or doing shopping.
After six months the over-60s who took part in the brain training were found to have significant improvements in carrying out daily tasks, while those over the age of 50 recorded better reasoning and verbal learning.
The improvements were most effective when people played brain-training games at least five times a week.
An earlier study by the same researchers suggested that such exercises offered no benefits for those younger than 50.
Last month scientists in California and Berlin spoke out against the brain-training industry, saying there is "little evidence that playing brain games improves underlying broad cognitive abilities, or that it enables one to better navigate a complex realm of everyday life".
But other research has shown some promise for brain training in improving memory, though these small-scale studies have been inconclusive.
Scientists have also shown that people who have complex occupations or stimulate their brains with activities such as crosswords, puzzles and learning new skills throughout life tend to have lower rates of dementia.
The research team believe the new study could be important for preserving mental functions in older people and help reduce the risk of decline of cognitive functions in later life.
Dr Anne Corbett, from the Institute of Psychiatry, Psychology and Neuroscience at King's College London, said: "The impact of a brain training package such as this one could be extremely significant for older adults who are looking for a way to proactively maintain their cognitive health as they age.
"The online package could be accessible to large numbers of people, which could also have considerable benefits for public health across the UK.
"Our research adds to growing evidence that lifestyle interventions may provide a more realistic opportunity to maintain cognitive function, and potentially reduce the risk of cognitive decline later in life, particularly in the absence of any drug treatments to prevent dementia."
Dr Doug Brown, from the Alzheimer's Society, said: "Online brain training is rapidly growing into a multimillion-pound industry and studies like this are vital to help us understand what these games can and cannot do.
"While this study wasn't long enough to test whether the brain-training package can prevent cognitive decline or dementia, we're excited to see that it can have a positive impact on how well older people perform essential everyday tasks."
Further studies of the impact of long-term brain training are now beginning.
:: The research was published in the Journal of the American Medical Directors Association.