"Faster, faster, until the thrill of speed overcomes the fear of death."
The euphoria doesn't last. There follows an intense mental depression and fatigue. Amphetamine depletes the neuronal stores of dopamine in the mesolimbic pleasure centres of the brain.
More than any other illegal drug, speed is associated with violence and anti-social behavior. Occasional light and infrequent use is probably relatively harmless; but heavy chronic use can lead to stereotypies of behavior, depressive disorders, "meth bugs" akin to cocaine-induced formication, strain on the cardiovascular system, increasing behavioral disintegration, and outright "amphetamine psychosis".