When using speed the drugs are targeting the brain’s ‘reward system’ and users will often crave that feeling again, which can lead to addiction.
The sense of alertness and energy a person experiences is due to these drugs speeding up the messages between the brain and the body. This leads to an increased heart and breathing rate and higher blood pressure.
One of the most common effects of amphetamine overdose is ‘speed psychosis’. This closely resembles the effects of paranoid schizophrenia, and usually begins with a heightened awareness of the environment and feelings of paranoia, anxiety and tension.