Sure, anything is possible. I haven’t read the original article, but this write-up is no doubt claiming more then the team researchers would claim. From the write-up it’s not possible to tell what it means to have a " healthy structure", how the age of the participants might have affected that, or what structural changes might actually mean (this would be a problem with the original study), if anything. Besides the fact that it could all just be a placebo effect. For me, there are just too many unknowns in write-ups like this. There are also all kinds of other things that reduce stress and that don’t need urban planning, such as puppies.