The neuropsychological mechanisms triggered by illegal drugs are also well understood.
Stimulants such as cocaine and amphetamines, including the popular drug Ecstasy, increase brain
concentrations of the pleasure-inducing neurotransmitter dopamine, as well as other energizing
neurotransmitters such as norepinephrine. Dependency on such drugs can arise because depletion of
these neurotransmitters produces cravings for more of the drug. Opiates such as heroin stimulate
special receptors in the brain leading to release of dopamine and subsequent feelings of pleasure and
relaxation, producing strong inclinations toward addiction. Enough is known about how such
powerfully addictive drugs work that we can confidently say that people use them to manipulate
mental states by changing their brain states.