Researchers at the University of California Irvine discovered a gene mutation that affects memory and can lead to poor driving skills. Tests on a driving simulator showed that subjects with the mutated gene performed 20% worse than those without it when asked to memorize and repeat a track. The gene is present in 30% of Americans and could explain many car crashes each year, so learning more about its effects on driving could help make roads safer. While the gene may cause problems with driving, it can also preserve mental sharpness in older age.