moviesDepictions of drinking alcohol in movies increased between 1996 and 2009, while smoking scenes decreased, according to a new study.

Researchers studied the placement and prevalence of alcohol and tobacco products in 1,400 movies during that period. Smoking and tobacco products decreased 42.3 percent in youth-rated movies, and 85.4 percent in adult-rated movies during that time frame.

In contrast, alcohol brand product placement in youth-rated movies increased from 80 to 145 per year, an increase of 5.2 appearances annually.

The researchers report in JAMA Pediatrics that the decrease in smoking in movies can be attributed to the Master Settlement Agreement of 1998, which required tobacco companies to change their marketing practices and to fund anti-smoking advocacy organizations.

Experts disagree about how much alcohol and tobacco scenes in movies influence young people's behavior, reports. Some point out it often isn't known whether teens start drinking or smoking before or after seeing particular movies.

A study published last year found watching movies with scenes that feature alcohol consumption doubles the likelihood that teens will start drinking alcohol. The two-year study of more than 6,500 American kids, ages 10 to 14, also found that teens who are exposed to alcohol-fueled movies are more likely to progress to binge drinking (five or more drinks in a row).

A second study published last year, which included more than 16,000 European teens, suggested the amount of drinking children and teens see in movies may influence their own drinking habits.