Teen Brains on Pot

Krista Lisdahl, assistant professor of psychology

Teen Brains on Pot

Marijuana is the No. 2 drug of choice among teens, behind alcohol, and its use has been increasing. With a prestigious grant that recognizes the nation’s most promising young researchers, UWM’s Krista Lisdahl is testing whether exercise could be brain-protective for young pot smokers.

Calm teenagers can reason almost as well as adults. But introduce a negative emotion, like stress, into their decision-making process and it’s a whole other story.

Regular pot use before age 16 has been shown to disrupt development of parts of the brain involved in the ability to make rational decisions, persist over time and withhold responses in the face of a negative emotion.

Since exercise increases blood flow to the brain and releases several brain-healthy chemicals, UWM neuropsychologist Krista Lisdahl wonders what the cognitive effects of exercise would be on young, regular pot users.

In a sweeping study of the interplay of these factors, Lisdahl is using three kinds of neuroimaging techniques and multiple measures of fitness among young pot users and non-using control subjects. The aim is to better understand the cognitive consequences of a chronic pot habit before the brain is fully “wired.”

Most of the research on how marijuana affects the brain has been done with adult subjects. Using functional magnetic resonance imaging, which allows the researchers to see specific brain connections as they happen, Lisdahl hopes to observe how brain communication differs in young users.

Her questions are wide-ranging: What will the imaging show after exercise? Is damage incurred from pot smoking reversible with later abstinence? And what can the developing brain tell us about addiction in general?

Like teen pot smokers with little impulse control, “many addicts say they are more likely to use again in response to a negative emotional trigger,” she says.

The study has earned Lisdahl the Presidential Early Career Award for Scientists and Engineers, the highest honor bestowed by the U.S. government on researchers in their early careers.