These kinds of studies are so dubious. Cause is stated when only correlation is implied. when no specific ingredients are listed while dealing with multi and varied ingredient substances, it reeks of low quality science.
Is it the high concentrations of B vitamins? caffeine? unlikely. The massive levels of sugar and corn syrup? quite possibly.
The system needs to find reasons why the younger generation is so depressed. It cant be the system they create and support. It must be “energy drinks”.