How Does Marijuana Affect the Developing Brain?

marijuana and the developing brain - wait until adulthood

In the 30s, the movie, "Reefer Madness" suggested smoking marijuana cigarettes causes insanity. Later, during the 1980's, commercials suggested using marijuana fries brain cells like an egg. While these over-exaggerations do little for building trust, teenagers and parents need to understand the risks associated with marijuana and the developing brain.

While cannabis consumption may not be as dangerous as other illicit and prescription drugs available today, research suggests marijuana and the developing brain may not pair well for everyone. During the teenage years, the brain develops in multiple ways, forming associations, connecting the dots, and creating efficiencies in how it functions, particularly in the processing of thoughts and emotions.

There are a few reasons to give the brain time to develop into adulthood before introducing compounds that could affect the way the brain develops.

Give Endocannabinoids a Chance

The Endocannabinoid System (ECS), found in all vertebrate animals, creates cannabinoids to help keep the body and mind operating at peak performance. In humans, our ECS produces two cannabinoids that we know of so far, Anandamide and 2-AG. Research tells us these compounds impact how the brain is formed – even before we are born and into our early 20s while the brain is developing.

In a report in the "Scientific American", Neurologist Yasmin Hurd of the Icahn School of Medicine at Mount Sinai reported there are massive changes in the concentration of endocannabinoids during the teenage years. Several brain-imaging studies suggest significant changes in the brain of habitual adolescent smokers:

  • Connectivity changes between the left and right sides of the brain
  • Weakened cognitive processing in teenage users
  • A smaller amygdala and hippocampus, which are involved in emotional regulation and memory

One study out of New Zealand followed 1,000 individuals all born in 1972. The participants underwent neuropsychological testing at ages 13 and 38. Additionally, the individuals were questioned about marijuana use at ages 18, 21, 26, 32 and 38. Those reporting higher levels of marijuana consumption experienced a 6-point decline in IQ, roughly the same as lead exposure.

The Counter Argument

Unfortunately, until the federal stance on cannabis changes to allow the necessary research, the impact of marijuana and the developing brain will likely remain a wildly debated topic. Just as plenty of research exists suggesting long-term impairment on the developing brain, other research contradicts these findings.

More recently, researchers published a new study in the "JAMA Psychiatry" journal, which reviewed the information from almost 70 studies over four decades of research. This review centered its attention on recreational marijuana consumption and cognitive function in more than 2,000 participants, comparing results to 6,500 non-cannabis-consuming individuals.

Despite scoring lower in attention, information processing speed, and delayed memory in cannabis users, researchers also noted these effects faded after three days of abstinence. Regarding the results, J. Cobb Scott, assistant professor of psychiatry at the Perelman School of Medicine at the University of Pennsylvania, told TIME Magazine, "There is biological plausibility that cannabis could cause changes in the brain that is still developing. But the abstinence data we have indicates that while those effects are detectable, they seem to go away after more than three days of abstinence."

Animal Studies on THC

Researchers in the United States typically run marijuana tests on lab rats and other animals. Many times, these tests use much higher doses of cannabis than even Snoop Dogg himself would consume. For example, Ronald Reagan once stated: "I now have absolute proof that smoking even one marijuana cigarette is equal in brain damage to being on Bikini Island during an H-Bomb blast." However, in the study he is referring to, the monkeys being tested wore gas masks which pumped the smoke, without any oxygen, into their lungs over the course of about 5 minutes. The monkeys died as a result of suffocation, not marijuana intoxication or brain damage caused by consuming it.

Marijuana and the Developing Brain: What Age is it Safe to Consume Cannabis?

Although most argue the brain is still developing into our early twenties, one study out of Montreal suggests that even waiting until the age of 17 gives the brain more time to develop. Compared to the brain of a 14-year-old, at 17 the brain becomes less vulnerable to the neurotoxic effects of marijuana which could affect how the brain develops.

However, research also suggests, age is only part of the equation. Genetics may also play a role in how marijuana affects the developing brain. Those with a particular gene, called AKT1, may have increased vulnerability to marijuana-induced psychosis.

Unfortunately, most people don't know their genetic code, nor can anyone easily predict how cannabis will impact the development of the human brain or the effects it may have later in life. While there are many adults who consumed cannabis in their rebellious teenage years and grew up to be highly successful individuals, there are many reasons to be cautious of marijuana while the brain is developing.