God knows I don't have near the anatomy and physiology knowledge that some here do, which is why I'm calling on all of them for their expertise.
This is my concern. I know all about thinking more quickly and recalling memory more easily and with more detail while on. I've experience this myself. I've experience the inflated sense of well being and confidence. But, what about how it could possibly result in one toping out in their cognitive ability sooner?
Take this as an analogy. Suppose you're rebuilding a muscle car and you can't decide between setting it with great acceleration or high top end speed. You can't have both. If your car has great acceleration and you top out in speed sooner. If you have high top end speed, you don't accelerate as quick.
Now, think of you cognitive ability before AAS as that car before you decide on acceleration or top end speed. Take AAS and you can think quickly and easily (acceleration), but you're ability to grasp high level concepts and theories may diminsh. Stay off AAS, and you don't think quite as quick as you would have, but it's still fast enough and you maintain that ability to comprehend highly complex thought (high top end speed).
I know this may seem a bit irrelevant, but anything I put in my body that could change it temporarily or permanently is something that I want to completely understand. Know what I mean?