From that link to an article abstract: --- Conclusions: Although use of hospitalized control subjects excludes individuals with less severe disease, leading

From that link to an article abstract: --- Conclusions: Although use of hospitalized control subjects excludes individuals with less severe disease, leading to selection bias, the study results suggest that caution should be exercised when prescribing high doses of amphetamines, with regular screening for symptoms of psychosis or mania. --- Just because you "know 3 people who got psychosis" is not evidence and not a reason to go around spreading nonsense and random links to article abstracts. The abstract you linked does, however, state that there seems to be a dose-response relationship to psychosis risk. That's part of the whole "prescribed and taken appropriately" thing and regular screening for symptoms of psychosis or mania. If you or someone you know has a concern about a prescription they take, talk to a f'ing doctor and don't make decisions based on something you found on the Internet.