Piedmont: Speaker gives frank talk on marijuana's impact on teens

PIEDMONT -- Marijuana changes the teenage brain and causes difficulty with memory and problem-solving among other effects, a psychology Ph.D. and registered addiction specialist told a packed house of parents and teachers at the Piedmont Education Speaker Series.

"How marijuana affects teenage brains is very, very different from how it affects adults," Abby Medcalf said during her 90-minute presentation at Piedmont High School on March 24. The drug affects the frontal lobes and executive thinking, inhibits the growth of myelin around neurons, affects memory, contributes to an abnormal shape of the hippocampus and changes the functions of the cerebellum, which controls coordination, balance and cognition, she said.

Abby Metcalf speaks before a packed crowd on the topic of marijuana's affects on the teenage brain at Piedmont High School on March 24. Metcalf's appearance was part of the Piedmont Education Speaker Series. ( Courtesy of Jennifer Fox )

The drug can also make students unable to read normal social cues and increases the risk of developing dependency and psychotic symptoms, according to Medcalf.

"Teens' brains are made for learning, getting 'out of the cave' and for experiencing things," Medcalf said. "Pot inhibits the brain's functions and can stunt learning."

Recent studies have shown that the brain is not fully developed until age 28, she said, and a single use of marijuana shows cognitive deficits days later in teenage brains.

Adults who smoke the same dose will return to their cognitive baseline much faster.

Medcalf said she was an addict herself and she now works at a Berkeley nonprofit drug and alcohol treatment facility. With 25 years of experience in the mental health and addiction field, she is confident that marijuana isn't the harmless drug many teens make it out to be.

Medcalf began the lecture by telling parents that the majority of high school seniors don't think occasional use of marijuana is harmful and that 45 percent of Piedmont High School 11th-grade students do not believe that it's bad for their health. But teens did 18 percent worse on long-term memory tests after using the drug and IQ points dropped by 6 to 8 points, according to a 2012 Duke University IQ study, she said.

She then went through a large number of statistics and random facts about marijuana. She said that teens who use marijuana increase the chances of them and even their offspring becoming addicts and said the risk of dependency on marijuana in general is one in 10 and for teens is one in six.


Medcalf also got political during her talk, saying that America is going to start seeing a storm of problems from Colorado and Washington state's legalization of marijuana, noting that infant and children admissions to the ER have gone up significantly since the drug was legalized in Colorado. She said that if the drug becomes legal, there will unquestionably be more deaths associated with it, saying that alcohol is currently more deadly because there's more of it. She also said that no medical marijuana patient has ever seen an improvement in their lives since receiving a medical marijuana license.

Her lecture also emphasized to parents that early alcohol use in teens is negative, even in religious or cultural contexts. She said that the first sips of alcohol should be delayed as long as possible.
"What we know is this: 'The younger to start even once, the greater the chance to become an addict,'" she said. "You want to delay. You don't want to use 'never.' Your job is 'Not on my watch.'"
Medcalf told parents they can get their teens to "just say no" to marijuana by telling them often that smoking or otherwise ingesting marijuana is not OK, unacceptable in the household and can bring punishment.

"Repetition is the mother of your job," she said. "That is the only thing they say works. You don't want to tell your kids to not smoke pot, you want to talk about it today, tonight, tomorrow and tomorrow night. You're branding on your children's brain, imprinting if you will."
To get teens to reject drugs and alcohol, they need to be interested and thrive in other activities, she said. Help or encourage them to master the guitar, water colors, swimming or soccer.

"What you want to focus on with your children is mastery, persistence and overcoming obstacles which builds their self-esteem," she said. "Self-esteem is the side-effect of mastery."
Medcalf's talk was the sixth and last in the 2014-15 Education Speaker Series, presented by the Piedmont Unified School District with the support of Associated Parent Clubs of Piedmont, Piedmont Educational Foundation, Piedmont Parents Network and individual donors.