The study's authors say the gene variation lowers available levels of a protein that boosts memory by helping brain cells communicate and work properly.
The researchers had 29 people drive 15 laps around a simulated driving course with difficult twists and turns. Four days later, they repeated the exercise. The subjects with the gene variant failed to remember much the second time around and performed worse both times compared to those without the variant.
One in three Americans has the gene variant.
The study is published in the journal Cerebral Cortex.