The amount of nicotine delivered to the brain through light cigarettes is almost as substantial as smoking a regular one, despite the lower levels of nicotine found in light cigarettes, a recent UCLA study concluded.
The researchers found that despite the varying amounts of nicotine in different types of cigarettes, a large amount of the nicotine receptors in the brain are occupied simply from smoking any cigarette with nicotine content, regardless of the amount.
Cigarette companies have long marketed light cigarettes as having less nicotine in the cigarettes.
Cigarettes with even half the amount of nicotine of regular cigarettes occupy a large amount of nicotine receptors in the brain, according to the study conducted by UCLA’s Psychiatry and Biobehavioral Sciences department and by the Greater Los Angeles Veterans Affairs Healthcare Center.
Nicotine binds molecules called nicotinic acetylcholine receptors to nerve cells in the brain.
As a result, a pleasure-inducing chemical called dopamine is released in the brain, which causes nicotine to be highly addictive, said Arthur Brody, UCLA psychiatry and biobehavioral sciences professor.
The researchers studied a wide range of nicotine content. The denicotinized cigarettes used in the study were from a brand called Quest, and they were specially designed with the nicotine removed, Brody said.
Smoking a regular cigarette resulted in 88 percent occupancy of the brain’s nicotine receptors, as found by the researchers in a previous UCLA study.
Regular cigarettes contain 1.2 to 1.4 milligrams of nicotine, Brody said.
The most recent study by the researchers took a couple of years to complete, he said.
The study was conducted to determine the percentage of the occupancy of the nicotine receptors in the brain caused by denicotinized cigarettes, which contain 0.05 milligram of nicotine, and light cigarettes, which contain 0.6 to 1 milligram of nicotine.
The previous study had not determined whether nicotine inhalation or other behavioral factors that occur during smoking resulted in the receptor occupancy, according to the researchers’ published article of the study.
According to the study, the researchers conducted the new study to determine if nicotine is solely responsible for the nicotine occupancy in the brain.
Positron emission tomography scans, a nuclear imaging technique which scans the functions of the body, were taken of each of the participant’s brain.
“What we did was inject a radiotracer (which detects radioactivity in the body) and it labels nicotine receptors in the brain. We have (the participants) smoke and we see the displacement of the radiotracer,” Brody said.
The scans were performed on different days in which each participant would smoke a different type of cigarette or not smoke at all, as a control scan.
The researchers then compared the before and after scans of each positron emission tomography session.
The researchers sought participants pertaining to their specific criteria for the study.
“We basically want smokers who are otherwise healthy, but are addicted to cigarettes. Nonsmokers are also used in our studies as a control group,” Brody said.
15 smokers participated in the study.
Some of the participants were scanned twice, resulting in a total of 24 positron emission tomography scans for the researchers.
The results of the study closely matched what the researchers had initially hypothesized.
The data showed that smoking a denicotinized cigarette occupied 26 percent of the nicotine receptors in the brain, and smoking a low-nicotine cigarette occupied 79 percent of the receptors, according to the study.
There is now an ongoing study on the effects of secondhand smoke at UCLA, Brody said.”There are no published studies on secondhand smoke and we’re doing a study right now,” he said.
“The main message is that it takes little nicotine in the system to occupy the nicotine receptors in the brain,” Brody said.