The brain is the central processing system for every of the body’s activities. It has a vast network of neurons that transmit information and electrical impulses to every part of the body. This intelligently created system has a build of reactors that are prompted to react to any external body within the body system.
The brain maintains a state of homeostasis (this is the situation where every of the body’s functions is kept at the optimum working conditions). Any change in the internal balance of the body results in the release of chemical substances to restore equilibrium.
Intake of drugs and other related substances disturb the internal balance of the body. So in response, the brain releases a substance called Dopamine. The release of Dopamine is what is responsible for the feeling of “highness” in persons.
The brain has an ancient system called the Limbic system. It is described as the reward system of the body. It accounts for why people feel the excitement and total dependency on substances and acts. Dopamine is the chief transmitter in this reward system.
When an individual takes a drug or a related substance, dopamine is released into the neural pathway. Normally, dopamine is supposed to pass through the pathway and be sucked up by the presynaptic neuron. By drugs change this normal sequence by ensuring dopamine is either not sucked up or it is released in excess quantities.
The continual delay of dopamine in the neural pathway increases the feeling of “highness” thus creating delusions.
As one of the brain’s superpower is adapting to changes and creating equilibrium, the brain perceives this change to be the new homeostasis. When next the individual takes the drug, he/she might not feel that sensation of “highness”. This forces them to take more amounts of the substance.
This act is what causes addiction. As the brain keeps adjusting the homeostasis, the individual will need more of the drug to become high. The limbic system is continually fed here hence the need to depend on the substance for feelings of enjoyment and excitement.