Continued abuse of amphetamines has occasionally led to violent acts that result from paranoia. They are fighting for their lives. Apparently some people are more likely to become psychotic from amphetamines than others. Due to the effect of tolerance abusers must take higher and higher doses of amphetamines to get the desired effects. This leads to side effects and adverse reactions that are common to amphetamine and other stimulants.
Strokes occur because high doses of amphetamine raise blood pressure far above normal levels.
Blood vessel walls weaken in places and occasionally burst just as a bicycle tire will burst if too much pressure is put into it. Therefore preventing seizures is an important emergency room treatment goal. There appear to be important differences between amphetamines used briefly and in low doses as opposed to high dose long term abuse. There is no reason to believe that the medical use of amphetamine causes brain damage. However over time, amphetamine abuse causes changes to brain tissue in several different ways.