DMG could be considered a naturally occurring adaptogen, as it plays a role in optimizing many bodily (and brain) functions. Personally, I feel the mechanism is its ability to donate methyl groups, optimizing the process of methylation. You'll see it lower homocysteine on your bloodwork, for example.
However, TMG aka Tri-Methyl-Glycine is the better compound here - especially insofar as methylation is concerned. There's also a lot more evidence for its performance enhancing effects. Higher IGF-1 levels, optimal cell hydration and even lowering cortisol. Given its cost to benefit ratio (and much better availability, vs DMG), it's likely your best option..