Your right, but RCT would take how long? 50 years? How can you make people not eat fructose or limit that for 50 years?
Wouldnt call the article junk sciensce. We also need hypothesis builing articles. I think they are proposing a specific mechanism of action about how fructose might cause Alzheimers.
I believe there are other clues also pointing in this direction, which I wont bore you with.
Just want to note, that I think everyone would prefer high powered RCTs, but I dont believe they are feasible to fund and run
Theory (almost) always precedes evidence, and coming up with a novel, biologically-plausible explanation for a common ailment is absolutely a valid, useful scientific contribution.
Your general point, that drawing firm conclusions would be radically premature, is spot on. I just stiffen up a bit when I encounter "RCT or GTFO" type arguments; where in the world do you think the ideas for which RCT to run come from?
As usual science communication is never done as well as we could all hope, but I personally like this "hierarchy of evidence" approach in understanding if something is ready to be consumed by the general public, rather than requiring further discussion with the scientific community.
This is the case in physics and astronomy. People make predictions that are not only untested, but we have to invent equipment to test them.
One of the great early accomplishments in science was when astronomers, observing our Sun, noted an unknown yellow spectral line signature. In 1868, Norman Lockyer predicted that it must be created by a hitherto unknown element, which he named “Helium” after the Greek Titan of the Sun, Helios.
In 1895, two Swedish chemists detected helium in ore samples here on Earth, and in the great tradition of the scientific method, we had a theory, a prediction, and a confirmation of the theory by test.
Einstein predicted things we’re still confirming empirically, but then again, he started by asking himself how the speed of light could be constant for every observer, which was the result of an experiment that failed to confirm a different theory.
Not exactly a "junk study." It's step 1 in a chain of studies that could validate this hypothesis.
A review article is a review article. It isn't a study.
I hope you're damn-well right. I love fruit and eat lots of it!
If you look at the evidence hierarchy, this study is at the lowest form of evidence (it's a narrative review -i.e expert opinion), they didn't even run a study.
The ultimate study would multiple randomized controlled trials showing sugar/fructose when controlled for calories, causes increased Alheimer's disease. Since we haven't seen that, we should not draw conclusions.
As the saying goes 'correlation does not imply causation'. We don't even have correlation yet, the headline is an overreach.