Its a neurosteroid. Its a part of most TRT protocols now at advanced clinics.
So yes, you inject testosterone and you also take DHEA as a part of that protocol. You have to be at the bleeding edge to know about this stuff. There's a whole cascade reaction they've been working on reconstructing for the last decade. The catalyst for this cascade reaction being the injection of exogenous testosterone and the consequences on the body (i.e. interruption of normal DHEA metabolism and production). High level researchers have been going back and reconstructing what your full hormone profile should look like and how to accomplish that.
Why did this start and why do people care? Simple. It started with a quest for what's called "morning wood". That's the standard being used right now at high level TRT clinics. If you don't have morning wood, one of these advanced protocols can potentially help with that. The doctors were able to zero in on cortisol balance as a major factor in morning wood, as well as several other hormones. No morning wood means your TRT protocol may be garbage and unhealthy.
A lot of guys are taking several different hormones as a result. Just simply taking testosterone is dark ages stuff.
DHEA is also good for lowering SHBG a bit, which happens to spike when using any type of ester testosterone.