Around 27.9 percent of those with European ancestry had this variant compared to 40.4 percent of those with African ancestry.
By the end of the study, 1,603 people with European ancestry developed dementia and 631 people with African ancestry developed dementia.
The study explained: “For people with European ancestry, researchers found that people with the highest scores in the lifestyle factors had a lower risk of dementia across all five genetic risk groups, including the group with the highest genetic risk of dementia.
“For each one-point increase in the lifestyle factor score, there was a nine percent lower risk of developing dementia.”