By Jonny Lupsha, Wondrium Staff Writer
Cravings for coffee and cigarettes are strong. However, since smoking was increasingly linked to cancer from the 1940s to the 1960s, anti-smoking campaigns have become more popular. New Zealand will raise its smoking age gradually until cigarette sales are obsolete.
In an effort to improve national health and cut down on certain cancers and emphysema, New Zealand has proposed to ban all cigarette sales—eventually. The plan will gradually raise the legal age to purchase cigarettes until it covers all residents. In the end, anyone born after a certain date will fall behind the rising age limit and never be able to buy cigarettes at all.
Cigarette cravings are surprisingly strong in smokers. In his video series The Addictive Brain, Dr. Thad Polk, an Arthur F. Thurnau Professor in the Department of Psychology at the University of Michigan, explains the dangers of nicotine and the desire to smoke anyway.
Where There’s Smoking
“Roughly one-third of the world’s adult population smokes tobacco on a regular basis,” Dr. Polk said. “Roughly 80% of them started before they turned 18—that’s why smoking is sometimes called a pediatric addiction. The same thing is true in rats. If rats start self-administering nicotine during adolescence, then they self-administer significantly more than rats that start administering nicotine in adulthood.”
Nicotine alone wouldn’t cause as much of a health crisis around the world, but cigarettes also have very harmful chemicals in them. According to Dr. Polk, cigarette smoke contains more than 50 chemicals that are known to cause cancer. These include arsenic, formaldehyde, and hydrogen cyanide.
“Smoking-related illnesses are estimated to kill more than five million people every year,” he said. “In particular, smoking is estimated to be responsible for 80-90% of lung cancer deaths. And for every person who dies, there are approximately 20 other smokers who suffer from at least one serious illness associated with smoking, such as heart disease or stroke.”
The average smoker’s life expectancy is 10 years shorter than a nonsmoker.
Nicotine and Acetylcholine
Acetylcholine is a neurotransmitter and it is used to make our muscles contract. According to Dr. Polk, it’s also associated with arousal, vigilance, and paying attention. Finally, it plays a role in our sleep-wake cycle. And like other neurotransmitters, it activates or inhibits receptors in the brain.
“Nicotine is an agonist for a class of acetylcholine receptors,” Dr. Polk said. “An agonist is a chemical that binds to a receptor and strongly activates it. Well, nicotine strongly activates acetylcholine receptors. In fact, the receptors that it activates have actually been named after nicotine: They’re called nicotinic acetylcholine receptors.”
The reason nicotine is so addictive is because of a region in the brain’s reward circuit called the ventral tegmental area (VTA). Neurons in the VTA communicate using dopamine, which Dr. Polk referred to as the “addiction molecule of the brain.” Dopamine is associated with increased cravings.
“Well, guess what kind of receptors these VTA dopamine neurons have on them,” Dr. Polk said. “One common type is the nicotinic acetylcholine receptor. Nicotine binds to these acetylcholine receptors on the VTA dopamine neurons and puts them into overdrive, overstimulating the reward circuit.
“The VTA dopamine neurons therefore fire a lot and they release unusually large quantities of dopamine.”
Dopamine release triggers cravings.