Dopamine is a neurotransmitter responsible for feelings such as pleasure, relaxation and happiness. Nicotine affects nearly every part of the human body, especially the brain. When nicotine and dopamine receptors interact, the brain changes how it creates dopamine and how it responds to dopamine. This reaction is the primary cause of addiction to nicotine.
Within seven seconds, nicotine makes its way from the lungs to the blood and into the brain. While the average cigarette contains only 1 mg to 3 mg of nicotine, this is enough to cause a long-lasting alteration of the human brain. Nicotine causes the brain to produce more dopamine than it usually does, which accounts for the stimulating and euphoric effects of tobacco use. The effect on dopamine levels in the brain is similar to the effect that amphetamines and psychostimulants have on the brain, making tobacco use comparable to the use of drugs such as cocaine.
When nicotine and dopamine receptors interact and the brain begins producing more dopamine in response to the nicotine, this causes the brain to reduce its production of natural dopamine. The organ essentially is taught that it only needs to create this neurotransmitter in response to the drug rather than in response to its natural function. While this process happens rather rapidly, it continues for long after nicotine use is stopped, accounting for the amount of tobacco users who quit the habit, only to go back to it months or years later.
Nicotine and dopamine play a trick on the human brain. When nicotine is first introduced to the body, while the brain is still producing dopamine naturally, it causes the brain to produce a much higher level of dopamine than it is used to producing. This, in turn, causes the brain to create more dopamine receptors to handle the amount of dopamine being produced, causing the brain to be more sensitive to the presence of nicotine and dopamine, and to their absence.
Nicotine and dopamine, when combined, are the primary reason for addiction to tobacco products and the withdrawal symptoms associated with quitting. The alteration of the brain to only produce dopamine in certain situations and the increase in dopamine receptors causes those who use tobacco products to need frequent and steady “fixes” to feel normal. This, coupled with the fact that the effects of nicotine typically wear off within minutes, is the primary reason why quitting tobacco products is such a difficult thing to do.