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: US scientists make embryonic stem cells from adult skin

add to favorites email to friend print save as pdf

Related Stories

Health concerns swirl around electronic cigarettes

Mar 26, 2014

With sales of electronic cigarettes, or "e-cigarettes," on the rise and expected to hit $1.5 billion this year, concerns over potential health risks of using the trendy devices are also gaining momentum and political clout. ...

Urban sparrows find new use for cigarette butts

Dec 05, 2012

Cigarette butts are widely reviled as an urban nuisance but birds in Mexico City see them as a boon, apparently using them to deter parasites from their nests, scientists say.

Study documents cigarette environmental hazards

Sep 06, 2013

Back in the bad old days when teenagers smoked cigarettes to be cool, it wasn't unusual for a teenage girl to surreptitiously pocket a cigarette butt left behind by a boy she had a crush on.

Recommended for you

Leeches help save woman's ear after pit bull mauling

Apr 18, 2014

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

New pain relief targets discovered

Apr 17, 2014

Scientists have identified new pain relief targets that could be used to provide relief from chemotherapy-induced pain. BBSRC-funded researchers at King's College London made the discovery when researching ...

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.

More news stories

Less-schooled whites lose longevity, study finds

Barbara Gentry slowly shifts her heavy frame out of a chair and uses a walker to move the dozen feet to a chair not far from the pool table at the Buford Senior Center. Her hair is white and a cough sometimes interrupts her ...

Cancer stem cells linked to drug resistance

Most drugs used to treat lung, breast and pancreatic cancers also promote drug-resistance and ultimately spur tumor growth. Researchers at the University of California, San Diego School of Medicine have discovered ...

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.