If research results on rats are applicable to humans, the longer a person holds out on that first cigarette, the better the chances of quitting later.

A study released late last year by USF researchers reveals more evidence for the long-recognized phenomenon that smokers who begin in their teens or early 20s find it harder to quit, as opposed to smokers who picked up the habit later in life. According to the study, which was performed on groups of rats at the Center for Aging and Brain Repair at the USF College of Medicine, nicotine has more of an effect on adolescent brains than on adult brains.

“Our research suggests that in the mammalian brain during adolescence, the brain is more sensitive to nicotine,” said Dr. Doug Shytle, psychiatry professor and lead researcher for the experiment. “And specifically in the sense that the stimulant effects of nicotine are more prevalent in the adolescent rats than in the adult rats.”

The experiment measured the movement of adolescent (1-month-old) and adult (6-month-old) male Sprague Dawley rats, some of which were given doses of nicotine while others were given a dose of saline solution for comparison, every day for a week. Groups of eight rats were placed in Plexiglas boxes, on the bottom of which were strips with infrared beams, Shytle said. When the rats crossed the beams, a computer connected to the strips recorded the rats’ movement in centimeters.

For the acute, one-day measurement, the adolescent rats showed both a depressant and a stimulant response, while the adult rats only showed a depressant response. Both the adolescent and adult rats showed heightened sensitivity to nicotine after seven days, but the adolescent rats had a greater locomotor response on average.

The results indicate what is also the case for humans. Given their higher susceptibility to nicotine, adolescents should pay extra caution. For college students, the presence of various cues, such as stress or peer pressure might act as an inducement to start smoking.

Students also may desire a cigarette in order to concentrate better while studying, as nicotine is known to increase attention span, Shytle said. But that is not sufficient reason to start puffing, he added.

“A better approach might to be come up with some exercise routine, circuit training or something like that, because that would definitely increase your energy levels and help you focus,” Shytle said.

In fact, a cigarette might only help the attention span of those who have already been smoking for a while, since inattention is known to be a symptom of withdrawal.

“The problem is even though nicotine does have this effect, what happens is the body adapts to it,” Shytle said. “So then, when you’re without the cigarette, you’re actually worse than you were to begin with. And that used to be a big criticism of the original studies where they said that smoking improves attention.”

Another commonly abused substance makes college students more likely to smoke and consume nicotine.

“College students are more likely to drink, and nicotine and alcohol go together hand-in-hand,” Shytle said. “I don’t smoke, but if I’m out with my friends, I’m more likely to say, ‘Hey, can I have a cigarette?’ Because there does seem to be an interaction — and they’ve studied this in animals too — between nicotine and alcohol, that the two have a synergistic type of effect.”

And apart from the most well-known adverse effects of nicotine, Shytle said other drugs, such as alcohol and even cocaine, appear to follow a pathway similar to nicotine’s within the body, and nicotine-blocking drugs also prevent other drugs from being effective.

“I’m a firm believer that if you wanted to pick one gateway drug to all other drugs, it would be nicotine,” Shytle said.

Once he secures the services of a post-doctoral assistant, Shytle said he will repeat the experiment using both male and female rats, but to determine nicotine’s effect on the turnover of cells, or neurogenesis, in the hippocampus region of the brain. The process is inhibited by stress and boosted by anti-depressants, and it is believed that nicotine acts to reduce neurogenesis, thereby acting against the effects of anti-depressants. The link between nicotine and depression is well-known, Shytle said, but the cause and effect of the relationship are still undetermined.

Contact Khari Williamsat oraclekhari@yahoo.com