Researchers at University of Pennsylvania tested a commercial brain-training program called Lumosity, and found it had "no effect on decision-making" and "no effect on cognitive function beyond practice effects on the training tasks."
From Penn Medicine News:
The researchers recruited two groups, each with 64 healthy young adults. One group was asked to follow the Lumosity regimen, performing the executive function games for 30 minutes a day, five days a week for 10 weeks. The other group followed the same schedule but played online video games instead. Both groups were told that the study was investigating whether playing online video games improves cognition and changes one’s decision-making.
The researchers had two assessments of decision-making that participants completed before and after the training regimen. To assess impulsive decision-making, the participants were asked to choose between smaller rewards now and larger rewards later. To assess risky decision-making, they were asked to choose between larger rewards at a lower probability versus smaller rewards at a higher probability. The researchers found that the training didn't induce any changes in brain activity or decision-making during these tasks.
The participants were also asked to complete a series of cognitive tests that were not part of the training to see if the program had any effect on their general cognitive abilities. While both groups showed improvement, the researchers found that commercial brain training didn't lead to any more improvement than online video games. Furthermore, when they asked a no-contact group, which didn’t complete commercial brain training or video games, to complete the tests, the researchers found that the participants showed the same level of improvement as the first two groups, indicating that neither brain training nor online video games led to cognitive improvements beyond likely practice effects.
Lumosity charges $15/month or $80/year for full access to its program.