A new brain-training app called Decoder has been experimentally shown to improve attention and concentration after just one month of use. The smartphone game, developed by scientists from the University of Cambridge, is now commercially available for Apple devices, but not all experts are convinced of the app's purported beneficial effects.

Decoder was developed by a team from the Behavioral and Clinical Neuroscience Institute at the University of Cambridge. In response to the many brain-training apps currently on the market that purport to result in cognitive improvements, the team behind Decoder wanted to be a little more rigorous and back up the claims with an experimental study.

The research split 75 healthy young adults into three groups. One group would act as a no-game control group, while the other two groups participated in eight, one-hour gameplay sessions over the course of a month. One game group played Decoder, while the other group played Bingo.

To test attention and concentration levels, at the beginning and end of the study all subjects completed what is called the Cambridge Neuropsychological Test Automated Battery Rapid Visual Information assessment. This test is claimed to be a "reliable and objective measure of sustained attention."

The study concluded that, after just one month of using Decoder, subjects displayed significant and meaningful improvements in attention and concentration compared to those subjects that played no games, and subjects that played Bingo.

While these positive results are certainly clear and convincing within the parameters described by the study, some experts are questioning how relevant they are to real-life cognitive outcomes. Til Wykes, from King's College London, suggests the research is welcome but it may not ultimately be that beneficial.

"The benefits seem to be limited to a computer test and only with supervised app use," says Wykes. "It may be more beneficial to spend the eight hours a month on other activities like going for a walk or the gym where there is plenty of evidence of cognitive and other health benefits."

Other researchers are suggesting any overall improvements in concentration identified by the study may stem from a fundamental similarity between the Decoder game and the test used to assess subjects.

"Brain training can boost performance in the short to medium term on tasks that are relatively similar to the original training," explains Thom Baguley, from Nottingham Trent University. "Here the main test and the Decoder game appear to share underlying similarities."

Baguley isn't the only expert to question the veracity of the study's conclusions in relation to a similarity between the the brain-training app and the test used to measure its effects. Nilli Lavie, from University College London, also suggests the app may not be as generally effective as the study claims.

"Normally, if you do brain training and you want to show effective training, you need to show some generalization," says Lavie in an interview with CNN. To conclude the brain-training app as effective in generally improving attention or concentration, the test to measure efficacy, "needs to be different to the training in order to say that it is not a content-specific task-specific training."

The Decoder brain-training app is commercially available through app developer Peak, which licensed the Cambridge technology. And while the authors of the newly published study suggest no commercial or financial relationships underpin the research, Barbara Sahakian, one of the Cambridge researchers working on the study, does declare she acts as a consultant for Peak.

The new study is published in the journal Frontiers in Behavioral Neuroscience.