Do 'light' cigarettes deliver less nicotine to the brain than regular cigarettes?

Sep 28, 2008

For decades now, cigarette makers have marketed so-called light cigarettes — which contain less nicotine than regular smokes — with the implication that they are less harmful to smokers' health. A new UCLA study shows, however, that they deliver nearly as much nicotine to the brain.

Reporting in the current online edition of the International Journal of Neuropsychopharmacology, UCLA psychiatry professor Dr. Arthur L. Brody and colleagues found that low-nicotine cigarettes act similarly to regular cigarettes, occupying a significant percentage of the brain's nicotine receptors.

Light cigarettes have nicotine levels of 0.6 to 1 milligrams, while regular cigarettes contain between 1.2 and 1.4 milligrams.

The researchers also looked at de-nicotinized cigarettes, which contain only a trace amount of nicotine (0.05 milligrams) and are currently being tested as an adjunct to standard smoking-cessation treatments. They found that even that low a nicotine level is enough to occupy a sizeable percentage of receptors.

"The two take-home messages are that very little nicotine is needed to occupy a substantial portion of brain nicotine receptors," Brody said, "and cigarettes with less nicotine than regular cigarettes, such as 'light' cigarettes, still occupy most brain nicotine receptors. Thus, low-nicotine cigarettes function almost the same as regular cigarettes in terms of brain nicotine-receptor occupancy.

"It also showed us that de-nicotinized cigarettes still deliver a considerable amount of nicotine to the brain. Researchers, clinicians and smokers themselves should consider that fact when trying to quit."

In the brain, nicotine binds to specific molecules on nerve cells called nicotinic acetylcholine receptors, or nAChRs. When nerve cells communicate, nerve impulses jump chemically across gaps between cells called synapses by means of neurotransmitters. The neurotransmitters then bind to the receptor sites on nerve cells — in the case acetylcholine resulting in the release of a pleasure-inducing chemical called dopamine. Nicotine mimics acetylcholine, but it lasts longer, releasing more dopamine.

"It can cause specific neurons to communicate and thus increases dopamine for an extended period of time," Brody said. "Most scientists believe that's one key reason why nicotine is so addictive."

In an earlier study, researchers determined that smoking a regular, non-light cigarette resulted in the occupancy of 88 percent of these nicotine receptors. However, that study did not determine whether inhaling nicotine or any of the thousands of other chemical found in cigarette smoke resulted in this receptor occupancy. The central goal of the present study was to determine if factors associated with smoking — other than nicotine — resulted in nAChR occupancy.

The authors reasoned that if nicotine is solely responsible for receptor occupancy, then smoking a de-nicotinized cigarette or a low-nicotine cigarette would result in the occupancy of roughly 23 percent and 78 percent of nicotine receptors, respectively, based on the cigarettes' nicotine content.

"That would still be substantial," Brody said.

Fifteen smokers participated in the study. Each was given positron emission tomography (PET) scans, a brain-imaging technique that uses minute amounts of radiation-emitting substances to tag specific molecules. In this case, the tracer was designed to bind to the nicotine receptors in the brain.

The researchers could then measure what percentage of the tracer was displaced by nicotine when the research subjects smoked. In total, 24 PET scans were taken of participants' brains before and after three different conditions: not smoking, smoking a de-nicotinized cigarette and smoking a low-nicotine cigarette.

The PET data showed that smoking a de-nicotinized cigarette and a low-nicotine cigarette occupied 26 percent and 79 percent of the receptors, respectively, which was very close to what the researchers had originally estimated.

Source: University of California - Los Angeles

Explore further: Growing a blood vessel in a week

add to favorites email to friend print save as pdf

Related Stories

Image: Galactic wheel of life shines in infrared

1 hour ago

It might look like a spoked wheel or even a "Chakram" weapon wielded by warriors like "Xena," from the fictional TV show, but this ringed galaxy is actually a vast place of stellar life. A newly released ...

Sex-loving, meat-eating reptiles have shorter lives

1 hour ago

The health risks and benefits of vegetarianism have long been discussed in relation to the human diet, but newly published research reveals that it's definitely of benefit to the reptile population. That, ...

Ericsson profit down 10 pct despite higher sales

1 hour ago

Wireless equipment maker Ericsson says its third-quarter earnings slumped 10 percent despite higher sales due to increased operating costs and negative effects from currency hedging.

Recommended for you

Growing a blood vessel in a week

22 hours ago

The technology for creating new tissues from stem cells has taken a giant leap forward. Three tablespoons of blood are all that is needed to grow a brand new blood vessel in just seven days. This is shown ...

Testing time for stem cells

Oct 24, 2014

DefiniGEN is one of the first commercial opportunities to arise from Cambridge's expertise in stem cell research. Here, we look at some of the fundamental research that enables it to supply liver and pancreatic ...

Team finds key signaling pathway in cause of preeclampsia

Oct 23, 2014

A team of researchers led by a Wayne State University School of Medicine associate professor of obstetrics and gynecology has published findings that provide novel insight into the cause of preeclampsia, the leading cause ...

Rapid test to diagnose severe sepsis

Oct 23, 2014

A new test, developed by University of British Columbia researchers, could help physicians predict within an hour if a patient will develop severe sepsis so they can begin treatment immediately.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Egnite
not rated yet Apr 24, 2009
Light cigarettes are a scam to sell more product to people who are less willing to smoke. It gives the impression they are less harmful but the simple fact is a light cigarette has the same ingredients as a normal cigarette. The only difference is that there are tiny holes around the light cigarette filter tip, allowing more air in the mix when you inhale. Therefore smokers who don't find this gives enough nicotine simple inhale longer giving the same effect as a normal.

Don't waste money on lights, if you want to smoke lightly, save your money and only smoke half as many cigarettes as u normally would.