Well this would be good news if there were no other studies on diet drinks. Unfortunately there are; there are studies that link diet soda to diabetes, which in turn then leads to the dementia. There are studies that lead directly from diet sodas to general weight gain, which leads to the stroke. So the author is either ignorant of these studies or is intentionally ignoring them to make headlines. In other words the author is saying “oh there’s no direct links from diet sodas to dementia or strokes” which is like saying there’s no direct link between jumping out of a 10 story window and death, which is true since I don’t die immediately after jumping out the window; you just have to give it enough time.