They don't appear to have run a control with caffeine alone. Caffeine is a well-established athletic performance-enhancing drug in its own right. Isn't this a serious flaw with the swim-test portion of this study?
I was under the impression that this is a pretty known effect. I used to take anti-depressants along with CNS stimulants and this definitely was something that my psychiatrist and my other doctors mentioned to me and considered when choosing an appropriate dosage.
Full title gives a bit more context: "Caffeine enhances the antidepressant-like activity of common antidepressant drugs in the forced swim test in mice."
The methodology here is typical for testing antidepressants with animals but many people find it somewhat horrifying:<p>First the mice are made to be depressed by exposing them to constant sounds of birds screeching and other predators. Next some are given the intervention. The level of depression is then measured by putting the mice in a container of deep water from which there is no escape, and timing how long until the mouse gives up swimming. The mice are not left to drown but are fished out and killed in a presumably more-humane way (chronically depressed mice are not otherwise useful).<p>A second ethical issue with studies with mice is that occasionally the unfortunate phd student tasked with dispatching the mice will not have been taught any way to do so and will have to try to come up with something on the spot. This can be quite traumatic for both parties.