Adolf Hitler's medical care (pdf) features an appendix with a handy (and very long) list of all of his personal physician's Theodore Morell's prescriptions with information about present day equivalents. This is based on Morell's diaries and it includes both amphetamines and barbiturates. As there is no information on dosages and frequency of use, it is hard to ascertain to what extent these drugs might have influenced Hitler's behaviour. The Medical Casebook of Adolf Hitler: His Illnesses, Doctors, and Drugs by Leonard and Renate Heston makes the case that all Hitler's faulty decision-making is to be attributed to his amphetamine use. On the other hand, Albert Speer, a very close associate of Hitler, who wrote an introduction to the book, seeems to doubt that, stating "even before Morell began treating him, all his endeavors were from the beginning limitless and irrational. [...] It would be a mistake to try to show Hitler as the unfortunate victim of addiction."

We will never know for sure, but let's put it this way. JFK used (probably large amounts of) barbiturates, painkillers, and amphetamines (see Robert Dallek's An Unfinished Life: John F. Kennedy, 1917-1963). Hitler used (probably large amounts of) barbiturates, and amphetamines. One has become the symbol for evil, the other was a beloved Democrat president. Let's not be too hasty in ascribing personality traits and political decision-making to the illnesses and medication use of nation's leaders.