Therapist Jennifer Golick has one piece of advice for young people who want to try marijuana:

“Just wait.”

The teen brain isn’t just an adult brain with fewer miles on it, doctors and scientists say. It’s a beta version — different, and still under construction.

So external influences — say, daily bong hits — can have a much greater long-term impact on a teen brain than they would on the brain of a 25-year-old grad student, 45-year-old professional or 65-year-old retiree.

In Marin County, where weed is as easy to find as a glass of good Cabernet, Golick has treated about 180 boys and girls who are dependent on cannabis.  She knows that the Reagan-era “Just Say No” message doesn’t work. But Golick, who works for Muir Wood Adolescent and Family Services, also knows that teens need to think ahead about the consequences of what they do.

“You should know what you’re getting into.  You should know what will happen,” she said. “Be an informed consumer — you make the choice.”

(Photo illustration by Pai/Bay Area News Group and

Research has shown that smoking cannabis is 114 times less lethal than drinking alcohol. The next most deadly substances after alcohol are heroin and cocaine,  followed by tobacco, Ecstasy and methamphetamine, according to the journal Scientific Reports.

But just because it’s less deadly doesn’t mean it’s not dangerous, researchers say.

Teens who engage in heavy marijuana use often show disadvantages in neurocognitive performance and brain development, said Sion Kim Harris, a research scientist with the Center for Adolescent Substance Abuse Research at Boston Children’s Hospital, a teaching hospital of Harvard Medical School.

Why is that so?

THC, the psychoactive ingredient in cannabis, suppresses the activity of neurons in a part of the brain called the hippocampus — the “command center” for memory and learning, Harris explained. So over time, with continued suppression, chronic users may end up with a smaller hippocampus.

That’s because THC occupies the same receptors on neurons as a natural brain chemical called anandamide. In essence, THC is acting as an imposter of this natural chemical.

The brain’s electrical pathways and the insulation process aren’t complete until the mid-20s, so teen brains are vulnerable to outside influences. In addition, teen brains are more “plastic.” They adapt and learn faster than adult brains — suggesting that teens are more vulnerable to developing an addiction.

Because these neurons are less active, the teen brain prunes away these neurons and their critical connections — reducing the ability to form memories.

“That is one of the biggest issues for teens — the ‘opportunity cost,’ ” Harris said. “Learning is the number one job for teens, and if they are having problems with learning, that will impact their ability to grow into adulthood.”

Scientists have seen another effect of early chronic cannabis use: faulty insulation of the brain’s wiring, she said. This insulation, called myelin, shows signs of structural problems in people who regularly used cannabis as teens, Harris said.

“So the implication is your brain is slower.” she said. “There’s a problem with cognitive processing. It’s not as sharp or as strong. It’s harder to maintain focus.”

An early age of initiation tends to be connected to greater differences in brain function during adulthood, concluded a major report in January by the National Academy of Sciences. “The brain does not complete development until approximately age 25, and data from the field of alcohol use reflect that substance use exposure during this period when the brain undergoes rapid transformation could have a more lasting impact on cognitive performance,” the report said.

While the academy found that it is difficult to document a direct link between cannabis use and educational outcomes — because so many variables play a role — it concluded that “this interference in cognitive function during the adolescent and emerging adult years, which overlap with the critical period in which many youth and young adults’ primary responsibility is to be receiving their education, could very well interfere with these individuals’ ability to optimally perform in school and other educational settings.”

Finally, teens are more vulnerable to developing mental illness as a result of using marijuana early in life, particularly if their families have a history of mental illness. “We are seeing these kids develop schizophrenia at a younger age than their parents or other family members developed it,” Harris said. “Marijuana use seems to be a precipitating factor.

“I don’t care who uses, or how often, if you’re over age 30,” she added. “But we’re seeing these critical developmental issues in people up to their mid-20s.”

Cody, a 23-year-old artist who grew up in the East Bay, felt a shift in his talents and ambitions after a casual habit grew into a dependency.

He tried it after watching “Weeds,” Showtime’s dark comedy, when he was 14.  “Something clicked, and I thought: ‘I want to smoke.’ It represented the creative aspect. I had never been high or anything before, save for the dentists’ office,” said Cody, who requested that the Cannifornian not his real name to protect his privacy. “I was curious. I think for a lot of my friends there was that feeling of reckless abandonment — and wanting to see what it is all about.

“At first, it was good. It was fun. It did help with the creative stuff,” he said. “I remember drawing and feeling like it loosened me up.”

But over time, his artistic ambitions faded. “After a while you get so high that you can’t or won’t draw anymore.  It excises that drive,” he said. “And the whole time I was smoking weed, I never had a real intimate relationship. Weed filled that desire. I wasn’t put together enough to follow through with anything — and 99 percent of a relationship is effort.”

Then, suddenly, he wasn’t  drawing at all. “That upset me,” he said. “And that was the initial reason to stop,” said Cody, who now attends Marijuana Anonymous meetings and is a straight-A student at an East Bay community college, studying animation and art. He hasn’t use cannabis for two years.

Cody said he’s met people who started at age 12 or 13, younger than he did, “and they don’t have the full capacity for memory. The earlier you start, the worse it is for you.”

Golick, the Marin County therapist, compares growing teen brains to the construction of a Ferris Wheel.

“If you’re at a carnival and a guy is putting together a Ferris Wheel, you want him to use every bolt available. You don’t want him to toss out a few,” Golick said.

“Same with your brain. You want to make sure all the bolts are in, and secure, before you start mucking with it,” she said. “Just wait — so you’re not the person who’s missing a few bolts.”

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