Marijuana and the Adolescent Brain

More and more states are legalizing marijuana for medical and recreational use. Researchers, doctors, educators, and parents are taking note and need to fully understand the health effects of cannabis use in minors.

You and your teen should consider these new research findings:

  • com and U.S. News and World Report released a 2018 survey that found 2.1 million middle and high school students have engaged in vaping marijuana.
  • Researchers in Europe found that marijuana can increase the amount of gray matter in a teenager’s brain, which affects adolescent development.
  • A new study in the Journal of Neuroscience found that after just one use of marijuana, the teenage brain can be altered.

We do know that marijuana can slow a person’s reaction time, make their heart race, and affect short-term memory. But what else might it do, especially to developing adolescent brains?

In one study, researchers scanned the brains of 46 14-year-olds from Ireland, England, France, and Germany. They found that those who used marijuana had higher brain volumes than those who didn’t. Specifically, brain volume referred to increased gray matter, a mass of cells that affect how humans mature over time.

Here’s why this matters. At age 14, the median age of the teens in the study, “Teens’ cortical regions go through a process of thinning or pruning,” says the lead author of the study and a professor of psychiatry. However, when marijuana was introduced, the increased amount of gray matter “disrupted this pruning process” which, in turn, interrupted the normal maturation process. But how much, or to what end, we don’t yet fully understand.

In addition to changing the teenage brain, marijuana also has other effects on the human body:

  • Tetrahydrocannabinol, better known as THC, is the main psychoactive component in marijuana. THC reacts with the body’s cannabinoid receptors resulting in slower reaction times to stimuli.
  • The National Institute on Drug Abuse has shown that marijuana can make a user’s heart rate temporarily jump. This feeling may last between 20 minutes and three hours and can cause a heart rate increase of up to 50 beats per minute. Since a usual resting heart rate is 60 bpm, this rate is nearly double the average.
  • Marijuana users may also experience issues with their short-term memory loss, since the THC affects how a brain processes information, according to a 2013 study.

Compounding all these verifiable health issues is what behavioral psychologists have long known about adolescent brains. That is, because the frontal cortex of their brains is still developing, adolescents are much more likely to engage in risky and experimental behavior. Additionally, vaping (rather than smoking) marijuana is seen as a cooler, more accepted way to get high. Plus, weed is now more readily accessible (often legal for those 21 years and older) across America and elsewhere.

Parents and their teens should take notice. Although we have research showing that marijuana affects the brain in some limited long- and short-term ways, we simply do not yet know what the long-term outlook is for teens who smoke or vape marijuana on an ongoing basis.

You might be surprised how little wine it takes to damage your brain


At INDY Neurofeedback, we hate to be the bearer of bad news, especially this time of year, but – contrary to what you may have heard, even one glass of wine a night is not a good thing – at least as far as your brain is concerned.

Many adults drink a glass of red wine a night with the understanding that it is good for the heart. And yes, studies have been telling us that moderate wine consumption may be better for your health than heavy drinking or abstaining from alcohol completely. But what does your brain have to say about it?

It turns out that even moderate alcohol intake (defined by researchers as seven to fourteen glasses of alcohol per week) may damage the brain over time. To reach this conclusion, researchers in the UK followed 550 people over 30 years, tracking:

  • weekly alcohol intake
  • cognitive, or thinking abilities, periodically
  • MRI brain scans at the end of the study

The results? A bit frightening, frankly. The more people drank, the more atrophy, or shrinking, was found in their brain’s hippocampal region. Since the hippocampus is an area involved in memory, this was significant. Even moderate drinkers were three times more likely to have hippocampus atrophy than people who abstained.

What about light drinkers? Those who drank less than seven ounces per week (about three-and-a-half glasses of wine,) didn’t have significant brain changes. But, importantly — and contrary to what we thought we knew — they didn’t experience any health benefits.

The most severe damage, not surprisingly, was found among heavy drinkers, or those who had over 30 ounces (more than about 15 glasses of wine) per week.

How to put this in perspective? Previous studies linking health benefits to moderate drinking may not have provided a complete picture. It is difficult to sort out – was it the alcohol is providing those benefits or were the people who drank only moderately simply healthier?

But, with researchers having tracked so very many people, over the course of so many years, revealing at least some evidence of physical and cognitive changes, at INDY Neurofeedback, we’re recommending that these study results should be taken (ahem) – soberly.

What does this mean for you? If you drink one drink per day during the week, and two drinks a day on the weekend, you have a higher risk of hippocampal atrophy, according to this study.

These findings contradict popular knowledge, previous studies, and the national recommendations on safe alcohol consumption. The study’s authors conclude that it “calls into question the current US guidelines.”

The bottom line: If you’re going to drink, limit yourself to one serving daily or less. Your brain will benefit from this discipline.

Just one season of football adversely affects a child’s brain development

Football and its relationship to brain health is still very much in the news. In fact, a new study found youth and high school football players who were hit in the head frequently showed signs of damage to their brain development after just one season of playing the sport!

“Football,” said Leanne O’Neil, “is absolutely dangerous to the brain – more so if you are a growing child. We see many football-related injuries here at INDY Neurofeedfack. It’s very troubling.”

In the new study presented at the Radiological Society of North America’s (RSNA) annual meeting, researchers observed 60 youth and high school football players over a single football season. None had prior concussions or histories of developmental, neurological or psychiatric problems.

Twenty-four players were determined to be high-impact players while 36 were placed in a low-impact group (based on each player’s risk of cumulative head impact exposure) according to the Head Impact Telemetry System (HITS), which helps collect data through sensors on the players’ helmets. Most impacts to the head occurred during practice, rather than at actual football games.

Those who experienced a high number of head impacts showed changes in brain pruning, a decrease in gray matter, which controls actions like motor, sensory movements and speech.

“A noticeable disruption in normal pruning means weaker connections between different parts of the brain,” says Leanne O’Neil. “This study found a significant decrease in gray matter pruning in the frontal default mode network of the brain. That’s the area involved in higher cognitive functions, such as planning and controlling social behaviors.”

In related research, the American Medical Association found that 177 former football players, ranging from high school to the NFL, showed some degree of chronic traumatic encephalopathy (CTE). CTE is a degenerative brain disease that has been linked to frequent head trauma.

Another study by Scientific American looked at the long-term risks of playing football. The study found more than 40 percent of former NFL players showed signs of traumatic brain injury.

Still another study, reported by TIME magazine, predicted that children who played tackle football before the age of 12 and continued to play in high school would have trouble managing behavior later in life.

Schools, institutions, parents, and coaches are taking notice, and some amendments to football practice, such as reducing the number of contact drills and the National Football League’s recommendation of the elimination of the “running start,” could help decrease the chances of injury. That said, “No child should be at risk of getting hit in the head at full speed,” says O’Neil. “It’s simply too dangerous.”

Currently, the National Institute of Health (NIH) is in the process of requesting more funding to follow up with these players longitudinally, to see if there are any longterm effects.

Chris Nowinski, Ph.D and the CEO and co-founder of the Concussion Legacy Foundation, went on record to caution parents not to allow their children to play tackle football before high school. “The risks to brain development are simply not worth the perceived benefits,” Nowinski said.