Whether or not researchers believe that brain training with computer games improves cognition, some have discovered a way to mine this vein for clinical research. Lumosity, the most prominent of the brain-training companies, has opened its gaming database to researchers as part of what it calls the Human Cognition Project. The database contains records of every mouse click from the 1.5 billion game sessions logged by the company’s 60 million users. Researchers from around the globe are sifting through it in search of patterns that may illuminate how aging, stress, sleep, and other lifestyle factors affect cognition. In particular, some scientists are panning the database for signatures of early decline that may flag people for prevention trials. Some researchers think brain games in general—which adapt to each user’s cognitive ability—may one day serve as cognitive diagnostics to monitor progression or help enroll clinical trials. Whether brain training boosts brain performance remains unclear (see Part 1 of the series), but in the meantime researchers are moving ahead to put the game data to some serious use.