Technically, nicotine is not significantly addictive, as nicotine administered alone does not produce significant reinforcing properties. However, only after coadministration with an MAOI, such as those found in tobacco, nicotine produces significant behavioral sensitization, a measure of addiction potential. This is similar in effect to amphetamine.

Modern research shows that nicotine acts on the brain to produce a number of effects. Specifically, its addictive nature has been found to show that nicotine activates reward pathways—the circuitry within the brain that regulates feelings of pleasure and euphoria.

Dopamine is one of the key neurotransmitters actively involved in the brain. Research shows that by increasing the levels of dopamine within the reward circuits in the brain, nicotine acts as a chemical with intense addictive qualities. In many studies it has been shown to be more addictive than cocaine and heroin, though chronic treatment has an opposite effect on reward thresholds.

Like other physically addictive drugs, nicotine causes down-regulation of the production of dopamine and other stimulatory neurotransmitters as the brain attempts to compensate for artificial stimulation. In addition, the sensitivity of nicotinic acetylcholine receptors decreases. To compensate for this compensatory mechanism, the brain in turn upregulates the number of receptors, convoluting its regulatory effects with compensatory mechanisms meant to counteract other compensatory mechanisms.

The net effect is an increase in reward pathway sensitivity, opposite of other drugs of abuse such as cocaine and heroin, which reduce reward pathway sensitivity. This neuronal brain alteration persists for months after administration ceases. Due to an increase in reward pathway sensitivity, nicotine withdrawal is relatively mild compared to alcohol or heroin withdrawal.

Nicotine also has the potential to cause dependence in many animals other than humans. Mice have been administered nicotine and exhibit withdrawal reactions when its administration is stopped. A study found that nicotine exposure in adolescent mice retards the growth of the dopamine system, thus increasing the risk of substance abuse during adolescence.

We strongly recommend to everyone reading this article to stay out of tobacco, however, if you or someone close to you have problems with nicotine addiction, we suggest you to visit DrugRehabServices.com.