In a study of 1,787 adults between 19 and 32, new study finds a significant relationship between depression and social media usage. Specifically, the more social media someone uses the more likely it is that they suffer from depression even after controll

Importantly, because this is descriptive data (describing the world as it is instead of manipulating variables) it is impossible to determine the direction of this effect. It is possible that (a) using social media causes depression, (b) having depression causes people to use social media more, (c) both depression and social media use are caused by other, unmeasured variables or (d) some combination of a, b and c.

While it's unsatisfying to not be able to make bold claims about causal mechanisms, this sort of descriptive research is an important first step in discussing complex phenomena.