Stimulants do have an anti-depressant quality in a similar sense to SNRIs. They stimulate release of extracellular neural serotonin and norepinephrine (SNRIs block reuptake of serotonin and norepinephrine. Before the accidental discovery of the first front-line antidepressants in the 50s, they were prescribed for depression.
However, for the reasons you mentioned, they aren’t very good antidepressants. It’s easy to mistake the early euphoria of amphetamine for reduction in depression. Without careful management, it’s easier to become tolerant or even addicted to amphetamine.
What studies? The information that I’ve found on PubMed and clinicaltrials.gov indicates that this is a poorly studied question, not a decided one.
A 2015 survey (Raymond Pary, MD, et al) found evidence that many psychostimulants were effective adjuncts for MDD and Bipolar depression. The results weren’t extraordinary but they were statistically significant. The authors noted in the results that the topic was generally poorly studied and double-blind clinical trials were limited.
In 2010-2011 Shire ran Phase II FDA trials on Vyvanse as an adjunct to traditional antidepressants for MDD with mediocre but also statistically significant positive results. Considering the age of most psychostimulants in use, that’s a fairly recent result from a clinical trial.
I certainly agree that psychostimulants are not a good choice to treat depression but that’s a far cry from “formally trialed for depression... don’t work”.
With the exception of MDMA, MDMA has show to have effective outcomes on depression and PTSD in short term studies. They problem is they have to be interleaved with SSRI's or the down state is far worse. That has been the issue with MDMA, it drops a depressed person lower than they where on the down ramp. Therefore there are concerns that it could place someone who was not suicidal in that low of a state. Studies have shown regulating this with SSRI's can mitigate the down state.
However, for the reasons you mentioned, they aren’t very good antidepressants. It’s easy to mistake the early euphoria of amphetamine for reduction in depression. Without careful management, it’s easier to become tolerant or even addicted to amphetamine.