researchers also found that greater physical activity at the start of the study lessened APOE e4-related cognitive decline two years later by an average of 0.00

researchers also found that greater physical activity at the start of the study lessened APOE e4-related cognitive decline two years later by an average of 0.007 points. So that sounds meaningless to me. Throw the numbers into the statistics machine I guess, but I bet a decline of 1.33 isn't meaningfully different than a decline of 1.323, even if you can confidently say you measured the difference.