Researchers Find the 1st Possible Negative Side Effect of Marijuana Use in Adults

Brain blood flow in those with cannabis use disorder was found to be significantly restricted. 

 

Man smoking a joint.
Man smoking a joint.

The stigma against marijuana in the US has been eroding for decades. But over the last ten years, use has skyrocketed. Since 2002, the number of Americans using the drug has almost doubled, according to a recent survey. In 2001, 4.1% said they had smoked marijuana within the past year. By 2014, 9.5% had done so. The number of patients using it to control the symptoms of an illness or disorder has risen substantially as well. Since it has been found far less dangerous that alcohol and other intoxicants, cannabis is quickly becoming the drug of choice for many Americans. New laws have allowed for medical marijuana in over half the states and recreational marijuana in about a half dozen.


Cannabis is also the most commonly used illicit drug in the world, according to the WHO. While opponents to liberalization often talk about it as a gateway drug, there is little evidence of this. In fact, scant data exists alleging that marijuana causes any damage whatsoever, if used in moderation, once the brain has stopped developing. But for chronic users, a new study imposes a harsh warning.

Researchers at Amen Clinics Inc. of California have found evidence that chronic use may increase the risk of Alzheimer’s. This is because it restricts blood flow to the regions of the brain where the condition takes root. Co-author Dr. Elisabeth Jorandby and colleagues recruited participants with marijuana use disorder. Around nine percent of users get addicted to cannabis. That’s a relatively low number.

Cannabis or marijuana use disorder is defined as using the drug chronically, even when it is clearly causing significant cognitive impairment. The symptoms may be mild, moderate, or severe, depending on the particular case. Chronic use is considered daily or near daily use. Those who habitually consume are more susceptible to psychiatric disorders.  

Medical marijuana is available in 28 states in the US today. Seven states now allow the recreational kind, and many more cities across the nation have decriminalized pot.

In this study, published in the Journal of Alzheimer’s Disease, 982 current or former chronic users and 92 healthy controls underwent brain scans to evaluate blood flow there. Those diagnosed with cannabis use disorder showed a significant reduction in brain blood flow in almost every region. The hippocampus, which is where Alzheimer’s originates, saw the largest reduction. This is the area responsible for learning and memory.

Few previous studies have evaluated blood flow inside the brain as an effect of chronic marijuana use, researcher’s said. This was measured using single photon emission computed tomography (SPECT). Participants had their brains scanned while performing a task and while at rest. Reduced brain blood flow would cause less oxygen to travel to neurons, which could lead to tissue damage.

Blood flow was especially restricted in the right hippocampus. Researchers believe marijuana may affect memory formation due to this effect. The study suggests consistent marijuana use causes damage to the brain. Possible effects include memory formation disruption. Other studies have suggested that restricted blood flow to the hippocampus can increase the risk of Alzheimer’s.

More research will have to be conducted to corroborate this claim. But it’s reasonable that someone who only lights up occasionally won’t have such an issue. This study conflicts with a 2014 preclinical trial, also published in the Journal of Alzheimer’s Disease. There, tiny doses of marijuana’s active ingredient, delta 9-tetrahydrocannabinol (THC) had neuroprotective qualities. It helped ward off Alzheimer’s by destroying beta amyloid proteins which are what cause the disease. So in the end, it may be an issue of dosage. A little is okay, but too much is damaging. But only more studies can tell us for sure.

To learn how marijuana affects memory in the short-term, click here: 

This is what aliens would 'hear' if they flew by Earth

A Mercury-bound spacecraft's noisy flyby of our home planet.

Image source: sdecoret on Shutterstock/ESA/Big Think
Surprising Science
  • There is no sound in space, but if there was, this is what it might sound like passing by Earth.
  • A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
  • Yes, in space no one can hear you scream, but this is still some chill stuff.

First off, let's be clear what we mean by "hear" here. (Here, here!)

Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.

All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.

BepiColombo

Image source: European Space Agency

The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.

Into and out of Earth's shadow

In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.

The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."

In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."

When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.

Magentosphere melody

The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.

BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.

MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.

Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.

Learn the Netflix model of high-performing teams

Erin Meyer explains the keeper test and how it can make or break a team.

Videos
  • There are numerous strategies for building and maintaining a high-performing team, but unfortunately they are not plug-and-play. What works for some companies will not necessarily work for others. Erin Meyer, co-author of No Rules Rules: Netflix and the Culture of Reinvention, shares one alternative employed by one of the largest tech and media services companies in the world.
  • Instead of the 'Rank and Yank' method once used by GE, Meyer explains how Netflix managers use the 'keeper test' to determine if employees are crucial pieces of the larger team and are worth fighting to keep.
  • "An individual performance problem is a systemic problem that impacts the entire team," she says. This is a valuable lesson that could determine whether the team fails or whether an organization advances to the next level.
Keep reading Show less
Photo by Martin Adams on Unsplash
Culture & Religion
She was walking down the forest path with a roll of white cloth in her hands. It was trailing behind her like a long veil.
Keep reading Show less
Scroll down to load more…
Quantcast