Opinions - Strange tolerance

[Madcow]

SWIM is able to come across amphetamine of different sorts from time to time, at which point, he likes to enjoy them

But as of late (within the past year or so), SWIM has been having issues with amphetamine tolerance. It's not the normal kind of tolerance, either. I don't even know whether it could be considered tolerance. The issue is not the fact that he doesn't feel anything when he takes it, but that he doesn't feel the euphoria/dopamine related feelings very much anymore, only the nor/epinephrine effects are prominent (these are diminished as well, but not as much).

I was doing some pondering about it and then it hit me. Could SWIM's recent opiate use (once a week on average) done something to affect the dopamine release to enough of a degree as to not feel very much euphoria?