(CNN) Just a few minutes of playing a certain video game could help identify the earliest stages of Alzheimer's in ways existing medical tests can't, researchers have found.

A new study used a smartphone app called Sea Hero Quest to monitor how gamers with and without a genetic predisposition to Alzheimer's navigate the virtual world, using their thumbs to move a little boat through a series of maritime mazes.

This type of test was key because "spatial navigation is emerging as a critical factor in identifying preclinical Alzheimer's disease," authors of the study, just published in the Proceedings of the National Academy of Sciences , said.

Players with a high genetic risk for Alzheimer's took less efficient routes to reach checkpoints in the game, researchers found. What's more, the movement patterns were identified among players in the genetic risk pool who had not yet displayed any other memory problems, they said.

By casting an online global net for survey subjects, scientists also managed to reach their conclusions in what might be described as warp speed. They marked the equivalent of five hours' worth of lab research for every two minutes of game play, they said, because vast sums of data about each player are available in every second of play.

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