Brain training, the booming market that promises to make you smarter, may do little more than make users proficient at brain games, according to a new study.

Healthy young adults who engaged in intense Lumosity brain-training for 10 weeks as part of the research got better at playing the game, but did not show any improvement in thinking skills such as memory, decision-making, sustained attention or ability to switch between mental tasks.

"Commercial (brain) training appears to have no benefits in healthy young adults," University of Pennsylvania researchers who conducted the study concluded in a paper published this week in the Journal of Neuroscience.

Study participants also did not show any reduction in impulsive or risky decision-making compared to "control" groups, the benefit the researchers had most hoped to see based on prior brain research. Such research has suggested increased activity in a particular brain region produces less risky, more rewarding decisions.

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More than 120 study participants, healthy adults 18 to 35 years of age, were assigned to either of two groups: one following the Lumosity regimen 30 minutes a day, five days a week; the other spending the same amount of time playing video games. Both groups underwent batteries of tests before and after the training to assess their decision-making and reasoning abilities. During the tests, the researchers monitored their brain activity using MRI scans

No significant differences in brain activity and decision-making between the two groups were found.

The study, the largest to date to rigorously examine brain-training games using cognitive tests and brain imaging, is the latest blow to a billion-dollar industry that has been accused of falsely claiming their programs can improve mental performance. Last year, Lumosity paid $2 million to the Federal Trade Commission to settle charges of misleading advertising, specifically that it lured customers with bogus claims its games could prevent mental declines and diseases, such as Alzheimer's.

The concept of brain training is still a matter of debate in the scientific community. In 2014, 75 academics, most psychiatrists, signed an open letter insisting the research doesn't support claims brain games make people smarter or stave off mental decline. In response, a group of 127 doctors, many leading figures in the field of neuroplasticity, responded with their own letter disagreeing with the notion there is any such consensus in the field.

Lumosity is the best know company in brain training, with more than 50 million users and subscriptions that run for $14.95 a month.

You can read the study here and a University of Pennsylvania press release about it here.