Youth who had never smoked conventional cigarettes but who used e-cigarettes were almost twice as likely to intend to smoke conventional cigarettes as those who had never used e-cigarettes, a new study shows.

More than a quarter million youth who had never smoked a cigarette used electronic cigarettes in 2013, according to a new CDC study. That is up from about 79,000 in 2011.

Among nonsmoking youth who had ever used e-cigarettes, 43.9 percent said they intended to smoke conventional cigarettes within the next year, compared with 21.5 percent of those who had never used e-cigarettes.

There is evidence that nicotine's adverse effects on adolescent brain development could result in lasting deficits in cognitive function. Nicotine is highly addictive. About three out of every four teen smokers become adult smokers, even if they intend to quit in a few years.

The CDC study was published in the journal Nicotine and Tobacco Research.

Read more at the Centers for Disease Control and Prevention.