How Does Weed Affect The Brain?

By Crystal Hessong

To answer the question of how weed affects the brain, you must first discern the age of the brain in question. Pot use affects older brains differently than it does younger ones. That’s because while the adult brain is fully formed, the teenage brain is still developing, so even if your body has stopped growing, your brain will continue to change until your mid-twenties. Substances such as marijuana can cause alterations in brain structure, function and neurocognition in the developing teen brain. And because your brain is still maturing, any changes to its structure could be permanent.

The neuroscience behind teen pot use

The way weed affects the brain's structure starts with its active ingredient, THC, which scientists believe affect the brain’s endocannabinoid system. This is the part of the brain that respond to THC and, according to the American Psychological Association, it’s “important for cognition, neurodevelopment, stress response and emotional control.” Teens who smoke weed on a regular basis can experience “dialed down cellular activity in the endocannabinoid system,” which can be problematic for developing brains. This may explain why teenagers are more susceptible than adults to long-term side effects, like a decline in IQ, of repeated marijuana use.

Why white matter matters

Researchers at the University of Barcelona reviewed numerous studies that focused on marijuana’s effects on the brain. What they found was that people who began smoking week before the age of 16 had higher rates of damage to their brains' white matter. The white matter is what allows the brain’s neurons to communicate with one another, and damage to it correlates with higher impulsivity. “Compared with users who began after 16,” the report shows, “early-onset smokers made twice as many mistakes on tests of executive function, which included planning, flexibility, abstract thinking and inhibition of inappropriate responses.”

What does this all boil down to? Smoking weed in your teens, and doing so frequently, can affect your brain development in a negative way.