When Gramps and crew sent back his report on what had really happened in Nazi Germany his conclusion was that without the methamphetamine, Hitler would have been no different than the many other hard line dictators of his time. He detailed how the drug itself increased intolerance of others, but that this was increased by the governments decision to add it to the general food supply which made certain groups of non conformists and dietary divergers stand out as a potential risk for disclosure of the plan. Everyone from Jews who ate Kosher to any kind of person who was impoverished and eating from their own garden or from begging exclusively had to be targeted for removal from the general population or someone might discover that the sole difference between in crowd and out crowd was diet.
Along with adding meth to the food supply propaganda was sent forth to explain why Germans could work harder and longer than the people in the neighboring countries. This increased the paranoia towards others, but as with many drugs, if the effects have a target they are harder to notice. Someone in real pain does not get high on opium just like someone with an acceptable target for fear and agression does not believe themselves to be paranoid and random occurrences of outlying paranoia can be blamed on whoever is hierarchically weaker, plus there were places where that kind of behavior was useful towards the common cause.
Hitler first encountered meth when dealing with the Japanese, who invented it. They made sure to introduce him to it early in their interaction and got him hooked on it deliberately. That was the sole explanation for their alliance.
Gramps strongly advised the US to come out clearly that the Germans were normal people under the influence of a drug and that under the same conditions any population could act this way. They went with half of his advise and then began research to see if they could minimize the side effects caused by meth.
*most Germans who lived through the transition period of war and post war who will say one word about the experience say it was like waking from a dream, that for some reason their behavior made sense at the time and that afterwards it no longer made sense, that it was hard to see themselves as accountable yet they really werent sure why*
