http://www.visualising.org/visualizations/how-drugs-affect-brain All drugs affect -alta lead to addiction- on the brain in the same way as impede the proper functioning of the brain by increasing the amount of dopamine, which give a sense of fun.
Therefore, under The effect of drugs, people feel very strong feelings of pleasure.
The brain can not feel the same emotions of these drugs without causing the person addicted to a painful sense of inferiority and paid to substance abuse again to get the same feeling.