Cigarette smokers know how hard it is to quit, and now it seems scientists understand why. New research coming out of the University of Pennsylvania has found that nicotine triggers the same brain pathways that give opiate drugs, like heroin, their addictively rewarding properties.
The study, led by Dr. Julie Blendy of the college's Transdisciplinary Tobacco Use Research Center, looked into the effects of nicotine on mice, the relationship between nicotine and environment, and this particular reward pathway. Researchers also said their findings suggest more effective ways that opiate blockers can be used to help smokers curb their nicotine habits. The findings were published in the June 16 issue of the scientific journal Neuron.
Nicotine's hold on smokers is believed to be due to its effects on brain levels of dopamine, which is linked to feelings of happiness and comfort, the study reports. Researchers also observed that nicotine-addicted mice preferred to stay in the chamber where they had previously received a nicotine fix, reinforcing the belief that certain situations and environments can trigger a desire to light up.
The nicotine-addicted mice showed a rise in levels of a protein called CREB, which is linked to the brain's response to many drugs. Levels rose not only when the mice were given nicotine, but also when they were in a place where they had been given nicotine in the past.
Mice given the drug Naloxone, which reverses the effects of heroin and other similar drugs, blocked both those responses, leading medical experts to explore the possibility of using opioid-blocking drugs to treat nicotine addiction. "Given the results reported here, clinical studies designed to evaluate administration of opioid antagonists just prior to cues associated with smoking could lead to a more promising treatment regimen," the researchers wrote in their report.
The highly addictive nature of nicotine has made it difficult for millions of Americans to quit smoking, including a growing number of teens. More than 90 percent of people age 10 to 22 who use tobacco daily have experienced at least one symptom of nicotine withdrawal when they tried to quit, the CDC reports, and approximately three-quarters of them say they smoke because "it's really hard to quit." Among 12- to 18-year-old smokers, 64 percent have tried to ditch the cigs, while 74 percent have seriously thought about it. In a 1992 Gallup poll, 70 percent of people 12 to 17 who smoke said they would never have started if they could choose again.
Recently, the tobacco industry has come under heavy fire from Congress, which is considering a bill that would ban the sale of flavored cigarettes, which some see as being targeted toward youths (see "Candy-Flavored Cigs Could Go The Way Of Joe Camel If Lawmakers Get Their Way"). In June 2000, a judge ruled that R.J. Reynolds, the same company that introduced the world to cartoon character Joe Camel, must change its ad-placement policies and pay a $20 million penalty for breaching a 1998 settlement that prohibited "indirectly targeting" teens with its ads.
In other advertising developments, popular magazines including Newsweek, Time, Sports Illustrated and People have agreed to eliminate tobacco ads from copies distributed to elementary, junior high and high schools, the New York Attorney General's office announced Tuesday (June 21).
Meanwhile, the Department of Justice is currently suing six of the largest cigarette manufacturers for $10 billion (down from its original proposal of $130 billion) for decades of illegal and harmful practices, including concealing the health risks and addictive nature of its products. The government claims the companies should fork over the money to help 45 million Americans quit smoking.