Amitha Kalaichandran, M.D., recently wrote an article for the New York Times that discussed tips for understanding medical studies and thinking critically about them.
She writes, "In August 2019, JAMA Pediatrics, a widely respected journal, published a study with a contentious result: Pregnant women in Canada who were exposed to increasing levels of fluoride (such as from drinking water) were more likely to have children with lower I.Q. Some media outlets ran overblown headlines, claiming that fluoride exposure actually lowers I.Q. And while academics and journalists quickly pointed out the study’s many flaws — that it didn’t prove cause and effect; and showed a drop in I.Q. only in boys, not girls — the damage was done. People took to social media, voicing their concerns about the potential harms of fluoride exposure."
Although the article ran in the NYT's Parenting category, these tips from experts in Kalaichandran's field could be applicable to anyone trying to figure out whether they should be concerned or not about medical news.
"1. Wet pavement doesn't cause rain." (i.e. "correlation does not equal causation").
Just because a study suggests there may be a link between two things does not prove that one causes the other.
"2. Mice aren't men."
If a study examines the effects of something in animals, that doesn't necessarily mean that the same would apply to humans.
"3. Study quality matters."
Randomized clinical trials and systematic reviews are the gold standard for study design. Other types of studies may offer weaker evidence.
"4. Statistics can be misinterpreted."
There is a difference between "statistical significance" and "clinical significance."
"5. Bigger is often better."
Studies that involve more participants may offer greater accuracy.
"6. Not all findings apply to you."
A study may have been done on groups of people who are different from you genetically, environmentally, or in other ways.
"7. One study is just one study."
Study results must be replicable in order to mean anything.
"8. Not all journals are created equal."
Look for journal articles that have undergone the "peer-review" process. When in doubt, Ask a Librarian.