Sunday, May 11, 2008

Stop Smoking: The Brain on Nicotine

Regardless of the reason why smokers say they smoke, the main reason is to experience the effects that nicotine has on the brain. Cigarettes are a very efficient nicotine delivery system. Inhaling smoke into the lungs is the fastest way to get nicotine to the brain. The lungs have a large surface area and the capillary walls are very accessible. Up to 90% of the nicotine in mainstream smoke is absorbed and it enters the arterial system and moves fairly directly to the brain, arriving within 7 to 10 seconds. The concentration of nicotine can be three times higher than if the nicotine was injected into the veins of a smoker because first the blood is pumped to the heart, then to the lungs, back to the heart before finally going to the brain. Even using medicinal nicotine replacement products does not give the same kick to the smokers brain because of the delivery system. Smoking or inhalation of nicotine gives higher, faster, and shorter surges of nicotine to the brain when compared to the nicotine replacement products.

Nicotine then needs to pass through the blood-brain barrier. Ammonia is added to tobacco to increase the PH of the cigarette because a higher PH allows nicotine to easier cross this barrier. Once in the brain nicotine binds to specific areas called nicotinic acetylcholine receptors. Every one is born with these receptors but when a person begins to smoke, then numbers of these specific receptors increases. We can say that nicotine is a brain disease because smoking changes the structure of the brain.Smokers have more receptors than non-smokers and smoking may allow the receptors to live longer.

Nicotine affects the different parts of the brain in different ways depending on the dosage. Smokers unconsciously regulate the amount of nicotine by either inhaling deeper or smoking more of the cigarette. Sometimes the smoker may use a cigarette to relax at other times as a stimulant depending on how deeply they inhale.

When nicotine occupies these receptors in the pleasure pathway, dopamine is released which causes pleasurable sensations (positive reinforcement) and removes unpleasant sensations of pain, anxiety or feelings of illness (negative reinforcement). When the brain has an increase in dopamine, it may be that this increases the attention that the individual places on external activities. These external activities become paired with the pleasurable sensations and become triggers themselves for smokers to light up. The brain becomes conditioned so that when a trigger such as answering the telephone, happens, the brain lights up and expects nicotine to occupy the receptors which the smoker experiences as “cravings”. So any event that a smoker does habitually can be paired with smoking and become a trigger to light up. The brain becomes conditioned to these pleasurable sensations and will “crave” nicotine when faced with these triggers even if they have just finished a cigarette.

Individuals smoke for a combination of both positive and negative reinforcement. When an individual starts smoking it is usually for the pleasurable effects and at some point the individual continues to smoke to avoid the unpleasant effects of withdrawals.

Individuals with depression, Attention-Deficit Hyper Activity, anxiety, schizophrenia and other mental conditions, will smoke to relieve negative sensations as a form of self-medication. Alcoholics and others substance abusers use nicotine in the same way also.

The other area of the brain that nicotine affects is the locus ceruleus which controls vigilance, arousal, concentration and stress reactions. It is also responsible for an individual’s response to stress, anxiety and panic, which may explain why smokers use tobacco in times of high stress and negative emotions.
During the quitting process, the smoker may experience withdrawals which are physical symptoms when a drug has not been used for a period of time. Withdrawals from nicotine includes insomnia, irritability, frustration, anger, anxiety, depression, difficulty concentrating, restlessness, decreased heart rate and a change in appetite. Medications can help with these symptoms.

Cravings are not the same as withdrawals. Cravings or powerful urges to smoke happen when the brain is conditioned to want nicotine either through positive or negative reinforcement. The brain is shouting, “Where is my nicotine?” Over time cravings become less intense and less frequent. Medications can help with these cravings. Relapse occurs when a smoker will reintroduce nicotine which immediately lights up the receptors in the smoker’s brain. Often only one cigarette is all it takes for the individual to relapse back to full time smoking again because of the strong effect nicotine has on the brain.

Just as with other addictive substance, nicotine changes the structure of the brain is is why it is so hard for a smoker to quit. As a society we need to understand that smokers smoke because they are addicted,not because they lack the willpower. They need our compassion, not nagging, and they need our support, not put-downs.

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