Parents already have enough worries about teens and addictions to video games and smartphone use. They now may have one more concern, which combines both they can get hooked on online gambling.

Researchers at the Canadian Centre for Addiction and Mental Health say free, casino-style online games may cause young people to develop gambling addictions later in life.

They studied three online casino games: Internet poker, internet slots, and Facebook social casino, in over 10,000 high-school students.

The results showed adolescents playing the games were more likely to gamble with real cash later on and between almost 40 to 50 percent who played social casino games and gambled with real money met criteria for low to moderate problem gambling.