The science of addiction.

[nsd_user663_3097]

Is Smoking Cigarettes Addictive?

50 million Americans smoke cigarettes. In the face of clear evidence that cigarettes cause lung cancer, outlined in a previous article in this series, why don’t smokers quit? Many of these individuals say they would like to, but can’t; they simply find it too difficult to overcome the habit. Anyone who has ever smoked cigarettes knows how difficult it is to quit. Most studies indicate a “quitting” success rate -- at least two year’s abstinence -- of about 20 percent. Despite this widespread experience, cigarette manufacturers have steadfastly refused to admit that smoking cigarettes is addictive, even swearing so under oath before congress last year. However, the maker of Chesterfield cigarettes, Liggett, has recently broken ranks with the other tobacco companies and in a legal settlement agreed that cigarettes cause cancer and are addictive. A tobacco spokesperson, addressing the question in the wake of the Liggett settlement, quibbled that the question has no answer, as addiction means different things to different people. Who is right? Is nicotine, the key ingredient, an addictive drug?

Is Nicotine an Addictive Drug?

Investigators attempting to explore the habit-forming nature of nicotine used what had been learned about cocaine to carry out what seems a reasonable experiment -- they introduced radioactively-labelled nicotine into the brain and looked to see what sort of carrier protein it attached itself to. To their great surprise, the nicotine ignored proteins in the between-cell gaps and instead bound directly to a specific receptor on the receiving nerve cell surface! This was totally unexpected, as nicotine does not normally occur in the brain -- why should it have a receptor there?

Intensive research followed, and researchers soon learned that the “nicotine receptors” were in fact designed to bind the neurotransmitter acetylcholine, and it was just an accident of nature that nicotine, an obscure chemical from a tobacco plant, was also able to bind to them. What then is the normal function of these receptors? The target of considerable research, these receptors turn out to be one of the brain’s most important tools. The brain uses them to coordinate the activities of many other kinds of receptors, acting to “fine tune” the sensitivity of a wide variety of behaviors.

When neurobiologists compare the limbic system nerve cells of smokers to those of nonsmokers, they find changes in both the number of nicotine receptors and in the levels of RNA used to make the receptors. They have found that the brain adjusts to prolonged exposure to nicotine by “turning down the volume” in two ways: 1. by making fewer receptor proteins to which nicotine can bind; 2. by altering the pattern of activation of the nicotine receptors (that is, their sensitivity to neurotransmitter).

It is this second adjustment that is responsible for the profound effect smoking has on the brain’s activities. By overriding the normal system used by the brain to coordinate its many activities, nicotine alters the pattern of release into gaps between nerve cells of many neurotransmitters, including acetylcholine, dopamine, serotonin, and many others. As a result, changes in level of activity occur in a wide variety of nerve pathways within the brain.

Addiction occurs when chronic exposure to nicotine induces the nervous system to adapt physiologically. The brain compensates for the many changes induced by nicotine by making other changes. Adjustments are made to the numbers and sensitivities of many kinds of receptors within the brain, restoring an appropriate balance of activity.

Now what happens if you stop smoking? Everything is out of whack! The newly coordinated system requires nicotine to achieve an appropriate balance of nerve pathway activities. This is addiction in any sensible use of the term. The body’s physiological response is profound and unavoidable. There is no way to prevent addiction to nicotine with willpower, any more than willpower can stop a bullet when playing Russian roulette with a loaded gun. If you smoke cigarettes for a prolonged period, you will become addicted.

Quitting Smoking

So what do you do, if you are addicted to smoking cigarettes and you want to stop? When use of an addictive drug like nicotine is stopped, the level of signaling along the many affected pathways will change to levels far from normal. If the drug is not reintroduced, the altered level of signalling will eventually induce the nerve cells to once again make compensatory changes that restore an appropriate balance of activities within the brain. Over time, receptor numbers, their sensitivity, and patterns of release of neurotransmitters all revert to normal, once again producing normal levels of signalling along the pathways. There is no way to avoid the down side. The pleasure pathways will not function at normal levels until the number of receptors on the affected nerve cells have time to readjust.

Many people attempting to quit smoking use patches containing nicotine to help them, the idea being that providing nicotine removes the craving for cigarettes. This is true, it does -- so long as you keep using the patch. Actually, using such patches simply substitutes one (admittedly less dangerous) nicotine source for another. If you are going to quit smoking, there is no way to avoid the necessity of eliminating the drug to which you are addicted, nicotine. Hard as it is to hear the bad news, there is no easy way out. The only way to quit is to quit.

©Txtwriter Inc.

txtwriter.com/onscience/Art...

[nsd_user663_2497]

So there is some science to actually back up the 'nicotine receptors' thing? I'd thought for the longest that it was all complete baloney, but hey there you go.

Last two paragrahps tell you all you need to know though. Stop all forms of nicotine. Hey presto.

Good find, Anti.

[nsd_user663_2497]

Cold Turkey is by the far the most successful and by design, direct way to quit (curious as to who's article made you sigh?). Figures put out there that NRT doubles your chances are total red herrings, the long term success rates are either lower or the same as going cold turkey, I cant remember which but this research is out there. Figures by the NHS themselves have been proven to be grossly inaccurate.

I also think its misleading to suggest it takes immense amounts of willpower to stop. In my opinion thats untrue and it isnt the most comforting thing for prospective quitters to have to read. Its all opinion of course, but thats just mine.

[nsd_user663_2497]

Its more CT here than it used to be thats for definite. At one time it was quite the opposite. To be fair, ideally it should be half and half to get a balanced view from both sides.

I do think anyone on NRT or any other medicinal methods is very welcome to voice their opinions here without fear of reprisal though.

[nsd_user663_3361]

I think it all depends on the individual and also how much they need/want to quit rather than what method they use to quit by.

What suits one wont suit another and i think its wrong to suggest that NRT stats are red herrings