Of mice and kids

If you're a young rat, you get a bigger buzz from nicotine than your rat elders.

And if it's true for rats, it's probably true for humans.

So says principal investigator Doug Shytle at the University of South Florida Center for Aging and Brain Repair. In research reported at the recent Society for Neuroscience meeting in Orlando, Shytle studied how nicotine influenced the level of activity in rats. Their movement was measured by counting how many times the animals broke infrared beams crossing their cages.

"We know that the more they get the drug, the more the hyperactivity increases," Shytle says. "What we found is that the adolescent rats had more activity than the adult rats" when given the same dose.

The rats confirmed previous research indicating that humans experience nicotine's effects on the brain differently depending on age. Results bolster the evidence that the "earlier one starts smoking, the harder it is to quit," Shytle says.

More than 80 percent of smokers tried their first cigarette before they were 18, says the American Cancer Society.

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