Frequent Marijuana Use in Teens and Young Adults Can Affect the Brain: Researchers

Using marijuana at least once a week can lead to cognitive decline, poor attention and memory and decreased IQ in teens and young adults, according to researchers at the American Psychological Association annual meeting.

Krista Lisdahl, Director of the Brain Imaging and Neuropsychology Lab at the University of Wisconsin-Milwaukee, noted that 6.5 percent of high school seniors reported smoking marijuana daily, up from 2.4 percent in 1993. Among young adults ages 18 to 25, almost one-third said they had used marijuana in the last month, Lisdahl noted in a news release. She said a 2012 study found people who have become addicted to marijuana can lose an average of six IQ points by adulthood.
“It needs to be emphasized that regular cannabis use, defined here as once a week, is not safe and may result in addiction and neurocognitive damage, especially in youth,” Lisdahl wrote in a study she so-authored in the journal Current Addiction Reports.