Haven't seen anyone else comment on this specific statement from the abstract: "No association was found with cross sectional cognitive performance or longitudinal changes in semantic fluency or word recall." Based on other people's comments, seems like the main finding here is that maybe the hippocampus shrinks as we get older and maybe there's an effect on lexical fluency. We already know that, even in "healthy" subjects, the brain shrinks due to aging, and I think no-one can say yet how much atrophy can take place before it impacts memory or learning.