Why You Can't Quit: The Science Behind Nicotine Additction

It is a well-established fact that smoking is linked to many diseases such as lung cancer and cardiovascular diseases. And yet, nicotine addictions are more common in America than any other addiction including alcohol and cocaine. We are well aware of the science and risks of this addiction—so why can’t we get people to stop smoking?

Dr. David Mannino asks this exact question in his article “Why Won’t Our Patients Stop Smoking?” in the Journal of Diabetes Care. Many (though not all) smokers would like to quit the habit, but struggle greatly. Long-term abstinence rates are extremely poor. “Among smokers who attempt to quit on their own, 80% relapse in within 1 month and 97% relapse within 6 months.” What is it about nicotine that makes the habit so hard to kick? Dr. Mannino mentions there are positive effects such as reduced anxiety, pleasure and arousal following the activation of nicotinic receptors. After prolonged exposure the result is a “desensitization of these receptors to nicotine and an increase in the number of receptors.” When someone tries to quit smoking, those desensitized nicotine receptors recover, causing symptoms of withdrawal such as anxiety, irritability, and cravings.  These uncomfortable symptoms tend to cause a relapse.

 

Dr. Daniel McGhee has done further research on the effect of nicotine at the University of Chicago with his study on “Nicotine Potentiation of Excitatory Inputs to Ventral Tegmental Area Dopamine Neurons.” Dr. McGhee’s lab exposed nicotine to brain slices from “drug-naive rats,” and “it was noted that there was NMDA receptor (NMDAR)-dependent increase of AMP receptor/NMDAR ratio in VTA DA neurons, which is consistent with the induction of LTP.” This means that that even exposure to the smallest amount of nicotine increases the AMPA/NMDA ratios in the VTA, and plasticity occurs. This increase in AMPA/NMDA ratios causes addiction.

Nicotine addiction and cravings are a dangerously vicious cycle, but with these scientific developments, we can make some changes. By knowing the science behind this addiction, we can more effectively develop medications and therapies to help people battle it. 

Works Cited:

Article: http://care.diabetesjournals.org/content/32/suppl_2/S426.full

Lecture: Dr. Daniel McGhee, February 23rd, 2013 Loyola University Chicago

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