MILWAUKEE - The images on the computer screen paint a picture of the impact marijuana has on the development of the brain of teens or young adults. Krista Lisdahl has been analyzing brain scans of 200 teens and young adults trying to determine the impact of smoking marijuana on a regular basis.
"What we see is that increased marijuana use, especially daily use, is associated with cognitive problems like slowed processing speed, poor complex attentions. They can memorize a phone number and things like that, but sustaining their attention over time is more difficult and there are also memory problems," said Lisdahl, an assistant professor in the Department of Psychology at the University of Wisconsin-Milwaukee.
Lisdahl has been studying the effects of marijuana on the human brain for the last 15 years. As the number of teens and young adults using marijuana regularly has been increasing, Lisdahl focused her study on them.
"They usually started at 15, 16 or 17, so I just wanted to see what is happening to the brain of a teenager when they are using regularly," Lisdahl said. "We've seen a jump, especially in teenager use, and actually about 6.5 percent of high school seniors are using marijuana daily."
Lisdahl has also studied the effects of binge drinking on the brain development of teens and young adults, and said studies show that can cause even more damage.
"I would agree that alcohol is a more dangerous drug," Lisdahl said. "Both of them are bad for the teenage brain."
The legalization of marijuana in Colorado and Washington and the decriminalization in 15 additional states has increased the debate nationally. Lisdahl believes that dialogue is needed.
"I'm happy that we're talking about this as a nation, and if we're going to legalize it I think there's a lot of things to consider, like are we going to cap THC," Lisdahl said.
THC is the ingredient in marijuana believed to be responsible for impacting the development of the brain in teens and young adults. In recent years, the percentage of THC in marijuana has been increasing.
One Wisconsin legislator, Rep. Melissa Sargent, plans to introduce a bill to change the way the state controls marijuana use by legalizing it.
"I've come to the conclusion that the most dangerous thing about marijuana in Wisconsin is that it is illegal," Sargent said.
As the mother of four children, she said Lisdahl's research findings are concerning.
"I was hesitant to tell you the truth. I've never used marijuana. I've got teenage kids. There's an awful lot of information that's out there that's pretty scary," Sargent said.
She believes that by regulating how marijuana is sold, where it is sold and to whom it is sold, there can be more control on use.
"That's why in my bill I do have a provision that there is an age of 21 before people are able to have access to it," Sargent said. "This will do a lot, I think, based on what I've seen in Colorado, to decrease usage among our young people."
While Lisdahl is very concerned about the impact her research shows regarding regular use of marijuana by teens and young adults, she agrees with Sargent that the prohibition of marijuana is not working.
"Is prohibition working? Well when it comes to marijuana, I'd have to say no, it is not working very well," Lisdahl said. "I support decriminalization and increasing methods like drug courts. I would prefer for people not to be treated like criminals because of their drug use but instead to get education about potential effects."
While Lisdahl's research clearly indicates the impact regular marijuana use has on teens and young adults, she is now looking for ways to diminish that impact. She is doing research on whether regular cardiovascular exercise can diminish the developmental effects marijuana has on the brain.
She believes additional research is necessary to keep pace with policy changes.
"I think that policy is moving faster than the research," Lisdahl said. "We absolutely need more research, and I hope that the states that decide to legalize or decriminalize invest in research."
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