there is also the matter of the nature of the effect
Amphetamines (the common type, phenethylamines excluded) are extraordinarily destructive to the human character. Bad stuff kids, stay away.
I knew a couple of hardened speed freaks growing up.
One was no longer there any more but looked physically fine. He used to go and live in the woods with carrier bags full of books. If you left him alone with any machinery he'd take it apart and stare at the bits.
The other was a living skeleton who was compos mentis 98% of the time, the other 2% his eyes would glaze over and foam would start pouring out of his mouth.
Fun times.