Hundreds of thousands of American youth are following marijuana-related Twitter accounts and getting pro-pot messages several times each day, researchers have found.
Scientists at the Washington University School of Medicine in St. Louis say the tweets are cause for concern because young people are thought to be especially responsive to social media influences.
In addition, patterns of drug use tend to be established in a person's late teens and early 20s. In a study published in the Journal of Medical Internet Research, the Washington University team analysed messages tweeted from May 1 through December 31, 2013, by a Twitter account called Weed Tweets@stillblazintho.
Among pro-marijuana accounts, this one was selected because it has the most Twitter followers - about 1 million. During the eight-month study period, the account posted an average of 11 tweets per day.
Principal investigator Patricia A Cavazos-Rehg, an assistant professor of psychiatry, counted 2,285 tweets during the eight-month study.
Of those, 82 percent were positive about the drug, 18 percent were either neutral or did not focus on marijuana and 0.3 percent expressed negative attitudes about it. Many of the tweets were meant to be humorous. Others implied that marijuana helps a person feel good or relax, and some mentioned different ways to get high.
With the help of a data analysis firm, the investigators found that of those receiving the tweets, 73 percent were under 19. Fifty-four percent were 17 to 19 years old, and almost 20 percent were 16 or younger. About 22 percent were 20 to 24 years of age. Only 5 percent of the followers were 25 or older.
"These are risky ages when young people often begin experimentation with drugs," said Cavazos-Rehg.
"It's an age when people are impressionable and when substance-use behaviours can transition into addiction. In other words, it's a very risky time of life for people to be receiving messages like these," she said. Cavazos-Rehg said it isn't possible from this study to "connect the dots" between positive marijuana tweets and actual drug use, but she cites previous research linking substance use to messages from television and billboards. She suggested this also may apply to social media.
"Studies looking at media messages on traditional outlets like television, radio, billboards and magazines have shown that media messages can influence substance use and attitudes about substance use," she said.
"It's likely a young person's attitudes and behaviours may be influenced when he or she is receiving daily, ongoing messages of this sort," she added.