It's funny how people who write headlines can completely get something wrong. Chances are those people are drinking a lot of coffee. A report from Entrepreneur showed a correlation between drinking a lot of coffee and intelligence, or lack there of.

But I've seen a few different headlines that claim that coffee causes stupidity. This is not the case. There just happens to be a relation between the amount of coffee you drink and your GPA. This comes directly from the Entrepreneur article.

According to the data, students who didn't drink any coffee had average GPAs of 3.43, while those who consumed one cup of coffee every day had an average 3.41 GPA, those who consumed two had a 3.39 GPA and students who drank five or more had GPAs of 3.28.

There could be lots of reasons for this relation. It's not necessarily coffee making you stupid. It could be that those with lower GPAs need to stay awake longer to study. Or maybe they like to party, so they need more coffee to get going in the morning. And that partying might effect their ability to retain information.