Which is more dangerous for your brain: Alcohol or marijuana?
Years of inconsistency in marijuana studies sent UC-Boulder researchers pouring over all the MRI data associated with alcohol and pot.
With medical and recreational marijuana gaining legality across the U.S. and in other countries, health experts are scrambling to find out what effect the substance actually has on human health, particularly the brain. Previous research has been mixed. Several studies support the claim that chronic use, starting in the teen years, can increase the risk of a psychotic episode later in life.
Most of these studies, however, find that participants who do have a psychotic breakdown after chronic, long-term use, were probably barreling toward such an episode anyway. Marijuana merely acted as a catalyst. Another important point: few studies look at occasional use, only chronic use, such as smoking pot daily or even multiple times per day.
So adolescence and teens should be made to steer clear of the stuff, but what about those of us with fully formed frontal lobes? And how does it measure up against, say, how alcohol affects the brain? Researchers at the University of Colorado-Boulder conducted a meta-analysis to find out. Their findings were published recently in the journal Addiction.
The combined studies included 853 adults between the ages of 18 and 55, and 439 adolescents between the ages of 14 and 18. The participants ranged in how frequently they used either alcohol or cannabis. While low-level alcohol consumption can be healthful for the brain, high or chronic consumption is known to decrease gray matter volume, even among young adults.
The two main types of tissue that make up the brain are gray and white matter. Gray matter contains cell bodies, dendrites, and axons. Whereas white matter is made up of the nerve fibers that control communications between brain clusters and all the other parts of the body.
Chronic alcohol consumption causes a loss of volume in the gray matter. Would marijuana do the same? Credit: Getty Images.
Study co-author Kent Hutchison is a professor of behavioral neuroscience at CU. Although previous research found diminished volume in certain areas of the brain from chronic marijuana use, those studies are inconsistent. Hutchison said in a press release, "When you look at these studies going back years, you see that one study will report that marijuana use is related to a reduction in the volume of the hippocampus. The next study then comes around, and they say that marijuana use is related to changes in the cerebellum or the whatever." He added: "The point is that there’s no consistency across all of these studies in terms of the actual brain structures."
So Hutchison and colleagues went back through the literature, examining all the MRI data concerning marijuana or alcohol consumption that had been collected over the years, paying particular attention to white and gray matter. The result? Cannabinoids—chemical compounds found only in marijuana, have no long-term impact on gray or white matter, a finding which contradicts years’ worth of previous studies.
In contrast, consistent alcohol use causes a significant decrease in gray matter volume. It also threatens the integrity of white matter. Those adults who have been drinking excessively for decades suffer the most damage, researchers say. According to Hutchison, "while marijuana may also have some negative consequences, it definitely is nowhere near the negative consequences of alcohol."
Hutchison says they were able to statistically control for those who consumed alcohol versus cannabis. Still, the study wasn’t without shortcomings. For instance, researchers only looked at marijuana use within the last 30 days. And in most cases, it was low-level use. What’s more, there could have also been subtle changes that weren’t picked up by the MRIs. While some previous animal studies have shown that marijuana has neuroprotective properties, studies in humans have been contradictory.
Would proving it’s not so bad for you clear the way for medical marijuana? Credit: Getty Images.
A large 2015 study using twins, concluded that brain differences between the two siblings existed way before marijuana use came into the picture and that it may be these brain differences that caused one twin to chronically use cannabis. This most recent study falls into line with a growing body of evidence that marijuana use, particularly occasional use as an adult, isn’t all that bad for you. The scientists do warn however that, although it may not be quite as damaging as other substances, that’s far from proving cannabis has medical benefits.
According to graduate student Rachel Thayer, lead author on the study: "Particularly with marijuana use, there is still so much that we don't know about how it impacts the brain." Far more research will have to be done to determine whether cannabis is helpful, harmful, or neutral when it comes to brain health. Hutchison, Thayer, and colleagues say that not only do we need more studies on the health effects of cannabinoids, we need more consistent ones as well.
To learn more about the debate on alcohol vs. marijuana, click here.
What do we see from watching birds move across the country?
- A total of eight billion birds migrate across the U.S. in the fall.
- The birds who migrate to the tropics fair better than the birds who winter in the U.S.
- Conservationists can arguably use these numbers to encourage the development of better habitats in the U.S., especially if temperatures begin to vary in the south.
The migration of birds — and we didn't even used to know that birds migrated; we assumed they hibernated; the modern understanding of bird migration was established when a white stork landed in a German village with an arrow from Central Africa through its neck in 1822 — draws us in the direction of having an understanding of the world. A bird is here and then travels somewhere else. Where does it go? It's a variation on the poetic refrain from The Catcher in the Rye. Where do the ducks go? How many are out there? What might it encounter along the way?
While there is a yearly bird count conducted every Christmas by amateur bird watchers across the country done in conjunction with The Audubon Society, the Cornell Lab of Ornithology recently released the results of a study that actually go some way towards answering heretofore abstract questions: every fall, as per cloud computing and 143 weather radar stations, four billion birds migrate into the United States from Canada and four billion more head south to the tropics.
"In the spring," the lead author Adriaan Dokter noted, "3.5 billion birds cross back into the U.S. from points south, and 2.6 billion birds return to Canada across the northern U.S. border."
In other words: the birds who went three to four times further than the birds staying in the U.S. faired better than the birds who stayed in the U.S. Why?
Part of the answer could be very well be what you might hear from a conservationist — only with numbers to back it up: the U.S. isn't built for birds. As Ken Rosenberg, the other co-author of the study, notes: "Birds wintering in the U.S. may have more habitat disturbances and more buildings to crash into, and they might not be adapted for that."
The other option is that birds lay more offspring in the U.S. than those who fly south for the winter.
What does observing eight billion birds mean in practice? To give myself a counterpoint to those numbers, I drove out to the Joppa Flats Education Center in Northern Massachusetts. The Center is a building that sits at the entrance to the Parker River National Wildlife Refuge and overlooks the Merrimack River, which is what I climbed the stairs up to the observation deck to see.
Once there, I paused. I took a breath. I listened. I looked out into the distance. Tiny flecks Of Bonaparte's Gulls drew small white lines across the length of the river and the wave of the grass toward a nearby city. What appeared to be flecks of double-crested cormorants made their way to the sea. A telescope downstairs enabled me to watch small gull-like birds make their way along the edges of the river, quietly pecking away at food just beneath the surface of the water. This was the experience of watching maybe half a dozen birds over fifteen-to-twenty minutes, which only served to drive home the scale of birds studied.
Explore how alcohol affects your brain, from the first sip at the bar to life-long drinking habits.
- Alcohol is the world's most popular drug and has been a part of human culture for at least 9,000 years.
- Alcohol's effects on the brain range from temporarily limiting mental activity to sustained brain damage, depending on levels consumed and frequency of use.
- Understanding how alcohol affects your brain can help you determine what drinking habits are best for you.
If you want to know what makes a Canadian lynx a Canadian lynx a team of DNA sequencers has figured that out.
- A team at UMass Amherst recently sequenced the genome of the Canadian lynx.
- It's part of a project intending to sequence the genome of every vertebrate in the world.
- Conservationists interested in the Canadian lynx have a new tool to work with.
If you want to know what makes a Canadian lynx a Canadian lynx, I can now—as of this month—point you directly to the DNA of a Canadian lynx, and say, "That's what makes a lynx a lynx." The genome was sequenced by a team at UMass Amherst, and it's one of 15 animals whose genomes have been sequenced by the Vertebrate Genomes Project, whose stated goal is to sequence the genome of all 66,000 vertebrate species in the world.
Sequencing the genome of a particular species of an animal is important in terms of preserving genetic diversity. Future generations don't necessarily have to worry about our memory of the Canadian Lynx warping the way hearsay warped perception a long time ago.
Artwork: Guillaume le Clerc / Wikimedia Commons
13th-century fantastical depiction of an elephant.
It is easy to see how one can look at 66,000 genomic sequences stored away as being the analogous equivalent of the Svalbard Global Seed Vault. It is a potential tool for future conservationists.
But what are the practicalities of sequencing the genome of a lynx beyond engaging with broad bioethical questions? As the animal's habitat shrinks and Earth warms, the Canadian lynx is demonstrating less genetic diversity. Cross-breeding with bobcats in some portions of the lynx's habitat also represents a challenge to the lynx's genetic makeup. The two themselves are also linked: warming climates could drive Canadian lynxes to cross-breed with bobcats.
John Organ, chief of the U.S. Geological Survey's Cooperative Fish and Wildlife units, said to MassLive that the results of the sequencing "can help us look at land conservation strategies to help maintain lynx on the landscape."
What does DNA have to do with land conservation strategies? Consider the fact that the food found in a landscape, the toxins found in a landscape, or the exposure to drugs can have an impact on genetic activity. That potential change can be transmitted down the generative line. If you know exactly how a lynx's DNA is impacted by something, then the environment they occupy can be fine-tuned to meet the needs of the lynx and any other creature that happens to inhabit that particular portion of the earth.
Given that the Trump administration is considering withdrawing protection for the Canadian lynx, a move that caught scientists by surprise, it is worth having as much information on hand as possible for those who have an interest in preserving the health of this creature—all the way down to the building blocks of a lynx's life.
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