Nicotine addiction – a sensitization-homeostasis theory


Published: 21-06-2015

Last modified: 29-03-2020

Smoking cigarettes causes psychological addiction, because it impacts  the pleasure center of the brain. It also addicts physically as a result of the development of tolerance to nicotine. Some time after smoking, addicts feel withdrawal symptoms, ie. restlessness, irritability, inability to concentrate, etc. – This is the traditional theory of nicotine addiction. Joseph R. DiFranza, working as a family doctor, is the creator of a new theory, called sensitization-homeostasis theory.

Research initiated by Joseph R. DiFranza proven that addiction in teenagers starts much faster than previously thought. The symptoms of addiction appear frequently during the first weeks of smoking and also when a teenager fired only two cigarettes per week. Other studies have shown that 10% of the addicts experienced symptoms of addiction already within two days of their first cigarette, and 25 – 33% within one month. Research by scientists in New Zealand have shown that every fourth teenager has symptoms of addiction after firing from 1 to 4 cigarettes in life. DiFranza does not explain it by tolerance to nicotine, because it can not develop so quickly. He also does not believe in a fun-smoking addiction because his observations and studies by Eric Moolchana indicate decreasing smoking pleasure with time. DiFranza found that cigarettes addict so quickly because they stimulate the craving-inhibition system. In non-smokers in their brain the craving-generation system and craving-inhibition system are in balance. For example, hunger causes the stimulation of craving-generation system that triggers appetitive behavior, ie. eating a meal. After satisfying the body, craving-inhibition system stops this behavior. Because nicotine stimulates the craving-inhibition system, the brain tries to restore the balance and develops adaptations that increase craving-inhibition system activity (ie. addictive adaptations). When direct effects of nicotine pass, the craving-generation system is still active and to re-balance the brain, you have to provide it with a new dose of nicotine. Subsequent doses cause greater effects than the previous one (it is called sensitization). As a proof of this theory are studies in which a conditioned stimulus was used to induce a desire for nicotine, alcohol, opioids and chocolate and researchers examined brain activity using functional magnetic resonance imaging (fMRI). Craving increased activity in a front cingulate cortex and other areas of the frontal lobe of the brain, suggesting that craving-generation system really exist. Other studies have shown that nicotine inhibits the activity of the same brain areas.

According to the sensitization-homeostasis theory former smokers do not feel constant craving, because their brains develop withdrawal adaptations which, as well as nicotine, inhibit craving-generation system. This means that their brain does not return to the state before they started smoking. This is confirmed by studies in rats whose brains were studied before, during and long after exposure to nicotine. After a period of abrupt nicotine withdrawal, there have been changes in the functioning of the brain cortex neurons transmitting signals through the serotonin and acetylcholine. The brains of ex-smokers therefore operate differently than the brains of smokers and non-smokers.

Hooked on Nicotine Checklist

Hooked on Nicotine Checklist developed by Joseph R. DiFranza is a proven method of measuring addiction. Answer “yes” to even one of these questions proves that addiction process has already begun:

  1. Have you ever tried to quit, but couldn’t?
  2. Do you smoke now because it is really hard to quit?
  3. Have you ever felt like you were addicted to tobacco?
  4. Do you ever have strong cravings to smoke?
  5. Have you ever felt like you really needed a cigarette?
  6. Is it hard to keep from smoking in places where you are not supposed to?
  7. Did you find it hard to concentrate because you couldn’t smoke?
  8. Did you feel more irritable because you couldn’t smoke?
  9. Did you feel a strong need or urge to smoke?
  10. Did you feel nervous, restless or anxious because you couldn’t smoke?


Joseph R. DiFranza „W nałogu od pierwszego papierosa”, Świat Nauki, nr 06/2008

Author: Maja Kochanowska

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