Does Smoking Weed Kill Brain Cells? [Here’s What New Studies Say]

There is a veritable ton of evidence which shows that alcohol kills brain cells. Anti-marijuana lobbyists suggest that marijuana does the same thing, but even if this were true, how come booze is legal since it also destroys brain cells? According to these lobbyists, it is okay to watch IQ-lowering TV while drinking Bud Light or some other foul-tasting generic beer, but you can’t smoke weed and contemplate the formation of the universe!

Origins of the Myth

I guess I’ve given away the answer to the title question already! The entire theory goes back to at least the 1970s and 1980s, although there was a fair amount of shady science doing the rounds in the 1930s too. The beginning of the 1970s was marked by America’s War on Drugs, which has proven to be a monstrous failure.

Back then, anti-marijuana lobbyists insisted that weed permanently damages the brain. While marijuana has short-term effects, it doesn’t have the same deleterious effects as alcohol or other narcotics in the long-term.

Sadly, there are websites such as Drug-Free World which continue to propagate the myth that marijuana kills your brain cells and turns you into a semi-literate fascist incapable of climbing stairs by yourself, let alone becoming the leader of a very powerful country. Such sites switch between pseudo-science, deliberate misreading of studies, and outright lies.

That being said, though, it would be remiss of us to say that cannabis doesn’t cause any ill-effects. However, the anti-marijuana crowd hugely overstates these effects, and don’t bother fact-checking or conducting full analysis before jumping to their faulty, pre-determined conclusions.

Exhibit A: The Infamous IQ Test Study

You’re unlikely to meet a proponent of the ‘weed kills brain cells’ theory that doesn’t cite the following study. It was conducted in New Zealand and published in 2012, and it followed the lives of over 1,000 people and compared their IQ at the age of 13 to their IQ at the age of 38. All 1,036 subjects were actually followed from birth in what became known as the Dunedin Study.

The subjects were interviewed aged 18, 21, 26, 32, and 38, and asked about their level of cannabis use each time. The study found that the IQ of people who regularly used weed fell by 8 points on average. Pretty much everyone who hates cannabis will say, “See! There’s your proof!” As usual, however, they fail to dig any deeper.

As it transpired, the study had a number of flaws which prevented it from being an accurate measurement of how weed impacts the brain. For example the drop in IQ was only apparent in ‘chronic’ users who had a physical dependence on the drug before the age of 18. Overall, only 38 people showed the steep drop in IQ and remember, they were using cannabis at least four days a week for over 20 years.

Furthermore, the possibility that differences in socioeconomic status could have accounted for the IQ disparity was never investigated. In other words, did these individuals drop out of school? Did they have a rough family life? We’ll never know.

A similar study published in December 2015 compared pairs of identical twins over a 10-year period. While twins that used weed experienced a drop of four points in their IQ, so did the non-users! The more likely reasons for falling IQ, rather than cannabis use, are environmental factors such as school, home life, and peer influence.

The Truth About Marijuana & Brain Cells

Research shows that there are temporary negative effects on the brain after using marijuana. For instance, weed can interfere with learning and memory for a short period. A 2001 study by Harvard University researchers looked at the cognitive performance of people while they were using pot, and after they quit.

The volunteers completed various intelligence, learning, memory, and attention tests during a period where they didn’t use marijuana, and results showed that heavy weed users scored far lower in memory tests during their first week after quitting. However, their score returned to normal within a month, which means that cannabis does not produce irreversible mental deficits.

Over the last 20 years, a large number of studies has shown that marijuana users have nothing to fear in terms of dropping IQ. In 2003, a team of researchers analyzed 15 previous studies which looked at marijuana’s long-term effects on the brain. They concluded that over a long period, marijuana users showed only a ‘minor’ level of impairment in learning and memory. Speaking at the time, lead researcher Igor Grant expressed his surprise: “I suppose we expected to see some difference in people who were heavy users, but in fact, the differences were very minimal.”

Likewise, in 2015 a study conducted at the University of Colorado Boulder compared the brain imaging scans of weed users to those who abstained. They concluded that cannabis users didn’t show any signs of physical changes in the major areas of the brain.

Downsides of Using Marijuana

While various studies have shown that cannabis use is unlikely to cause significant brain changes, the outlook is not as clear amongst adolescent users. It is worth remembering that during this period, the brain has not fully developed which means smoking weed as a teenager could be a very bad idea. The research isn’t conclusive, but it makes sense that using marijuana while your brain isn’t fully formed could cause damage later on. We support the idea that weed should only be legal to adults. After all, subjects in the Dunedin Study that experienced a drop in IQ began using weed as teenagers.

There are also dangers associated with smoking marijuana. When you smoke, your brain loses oxygen in some areas, which could result in cellular damage. If you’re concerned about this issue, invest in a vaporizer or consume edibles.

Can Weed Help Your Brain?

Reefer Madness advocates look away now, because there is evidence that using marijuana can actually help your brain! There are concerns over neurotoxins such as fluoride and aspartame. These toxins cause the malfunction of nerve cells, but certain compounds in cannabis prevent the damage to the brain caused by neurotoxins. Also, cannabinoids are excellent antioxidants which also fight back against brain cell damage.

In a 2015 study, it was discovered that CBD can reduce a neurotoxin known to trigger Parkinson’s disease. Further research shows that THC could reduce the inflammation and amyloid plaque build-up that results in Alzheimer’s disease. Finally, there are cannabis compounds that promote neurogenesis, which means ‘promoting the growth of new brain cells.’

Final Thoughts on Weed & Brain Cells

Not only is the ‘weed kills brain cells’ theory a complete myth, but it is also the sheer opposite of reality! In certain circumstances, marijuana helps brain function, and while we are wary about adolescents using it, dozens of studies have determined that cannabis causes no long-term brain damage in adults, or drop in memory, ability to learn, etc.

Nonetheless, marijuana is still Public Enemy Number One in the eyes of some. Meanwhile, we continue to ply ourselves with alcohol even though it is proven to have a negative impact on our brain cells. A 2017 study by Thayer et al. for example, found that while chronic alcohol use was associated with lower gray matter volume and white matter integrity, the same could not be said for marijuana.

It seems that no matter how much data we have that proves marijuana doesn’t kill brain cells, anti-marijuana lobbyists will always twist the information to meet their agenda, just like the infamous New Zealand IQ study.

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