Smoking weed linked with higher sperm counts, says Harvard

The counterintuitive findings bode well for stoners, but more research is needed.

  • Marijuana research in the past has found that using the drug is linked to lower testicular health.
  • New research from Harvard, however, suggests the opposite: Marijuana users have more and better quality sperm.
  • These unexpected findings highlight how poorly we understand marijuana's effect on the human body.

The opening crawl for the 1936 film Reefer Madness reads "[Marijuana's] first effect is sudden violent, uncontrollable laughter, then come dangerous hallucinations — space expands — time slows down, almost stands still... fixed ideas come next, conjuring up monstrous extravagances — followed by emotional disturbances, the total inability to direct thoughts, the loss of all power to resist physical emotions... leading finally to acts of shocking violence... ending often in incurable insanity."

Fortunately, marijuana's reputation has come quite a ways since then. Its medicinal properties are widely recognized, 10 states (as of this writing) have legalized it, and its status as a comparatively healthy alternative to alcohol and tobacco is clear. Now, new research from Harvard is giving marijuana a further bump in its reputation.

Prior research has found that marijuana usage can have a troubling side effect for men—according to a handful of studies, it reduces men's sperm counts and quality. This obviously undesirable effect, though, may not actually be the case. In fact, the opposite might be true.

Researcher Feiby Nassan recently contributed a study to Human Reproduction — it was published on February 6 — focusing on the testicular function of men who used marijuana. Between 2000 and 2017, Nassan and her colleagues collected 1,143 semen samples from 662 men at the Massachusetts General Hospital Fertility Clinic as well as questionnaires on their history with marijuana. Contrary to their original hypothesis, Nassan found that men who had smoked just two joints in their lifetime had "significantly higher" sperm concentrations. What's more, frequent users of marijuana had higher levels of serum testosterone as well.

In a press release, co-author Jorge Chavarro said, "These unexpected findings highlight how little we know about the reproductive health effects of marijuana, and in fact of the health effects of marijuana in general. […] Our results need to be interpreted with caution and they highlight the need to further study the health effects of marijuana use."

Feiby Nassan et al., 2019

Nassan and colleagues compared men who had never smoked, had smoked in the past, or were current smokers according to where they fell based on recommended fertility markers set out by the WHO. In the graph above, we can see that marijuana smokers — often regardless of whether they were past or current smokers — were more likely than non-smokers to meet these minimum healthy criteria. For example, non-smokers were more likely to have less than 15 million sperm per milliliter, more likely to have less than 39 million total sperm, and more likely to have fewer mobile sperm (i.e., sperm motility). They also had fewer progressively motile sperm, meaning their sperm failed to move in a straight line, swimming in circles instead, as well as more sperm with abnormal morphologies.

That being said, current smokers were more likely to have less ejaculate volume and more sperm with abnormal morphologies. Overall, the results suggest that moderate use of marijuana may be the best bet.

While the results seem clear, it's important to take this research with a grain of salt. Firstly, this was a correlation study: there was no way to say whether smoking marijuana caused these differences, just that they were associated. Furthermore, there's a few different ways to interpret the results. Nassan explains that there are two different possible interpretations: "The first [is that] that low levels of marijuana use could benefit sperm production because of its effect on the endocannabinoid system, which is known to play a role in fertility." Endocannabinoids are a broad group of neurotransmitters that bind to cannabinoid receptors throughout the brain and peripheral nervous system. They handle a few different jobs in the body, including regulating appetite, mood, motivation, and—of course—fertility. Tetrahydrocannabinol, or THC, is the main psychoactive ingredient in marijuana, and it binds to these receptors, producing the high associated with the drug and potentially improving aspects of fertility.

"But," says Nassan, "those benefits are lost with higher levels of marijuana consumption." Nassan's own results showed some downsides to current marijuana use, and, as mentioned previously, prior research has shown that fertility can be reduced in heavy smokers.

The second interpretation, says Nassan, "is that our findings could reflect the fact that men with higher testosterone levels are more likely to engage in risk-seeking behaviors, including smoking marijuana." Testosterone has an array of behavioral and physiological effects in men. It's associated with both reproductive health, as well as behaviors like aggression and risk-taking. It could be that high-testosterone men seek out marijuana and other drugs, skewing the results of the study.

Ultimately, the true conclusions we can draw from Nassan's study is that we simply don't know enough about marijuana. Its pariah status has clouded the general public's understanding of its true nature. Now that its gaining broader acceptance, it's more important than ever to research marijuana and study its effects on the human body.

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Yale scientists restore brain function to 32 clinically dead pigs

Researchers hope the technology will further our understanding of the brain, but lawmakers may not be ready for the ethical challenges.

Still from John Stephenson's 1999 rendition of Animal Farm.
Surprising Science
  • Researchers at the Yale School of Medicine successfully restored some functions to pig brains that had been dead for hours.
  • They hope the technology will advance our understanding of the brain, potentially developing new treatments for debilitating diseases and disorders.
  • The research raises many ethical questions and puts to the test our current understanding of death.

The image of an undead brain coming back to live again is the stuff of science fiction. Not just any science fiction, specifically B-grade sci fi. What instantly springs to mind is the black-and-white horrors of films like Fiend Without a Face. Bad acting. Plastic monstrosities. Visible strings. And a spinal cord that, for some reason, is also a tentacle?

But like any good science fiction, it's only a matter of time before some manner of it seeps into our reality. This week's Nature published the findings of researchers who managed to restore function to pigs' brains that were clinically dead. At least, what we once thought of as dead.

What's dead may never die, it seems

The researchers did not hail from House Greyjoy — "What is dead may never die" — but came largely from the Yale School of Medicine. They connected 32 pig brains to a system called BrainEx. BrainEx is an artificial perfusion system — that is, a system that takes over the functions normally regulated by the organ. The pigs had been killed four hours earlier at a U.S. Department of Agriculture slaughterhouse; their brains completely removed from the skulls.

BrainEx pumped an experiment solution into the brain that essentially mimic blood flow. It brought oxygen and nutrients to the tissues, giving brain cells the resources to begin many normal functions. The cells began consuming and metabolizing sugars. The brains' immune systems kicked in. Neuron samples could carry an electrical signal. Some brain cells even responded to drugs.

The researchers have managed to keep some brains alive for up to 36 hours, and currently do not know if BrainEx can have sustained the brains longer. "It is conceivable we are just preventing the inevitable, and the brain won't be able to recover," said Nenad Sestan, Yale neuroscientist and the lead researcher.

As a control, other brains received either a fake solution or no solution at all. None revived brain activity and deteriorated as normal.

The researchers hope the technology can enhance our ability to study the brain and its cellular functions. One of the main avenues of such studies would be brain disorders and diseases. This could point the way to developing new of treatments for the likes of brain injuries, Alzheimer's, Huntington's, and neurodegenerative conditions.

"This is an extraordinary and very promising breakthrough for neuroscience. It immediately offers a much better model for studying the human brain, which is extraordinarily important, given the vast amount of human suffering from diseases of the mind [and] brain," Nita Farahany, the bioethicists at the Duke University School of Law who wrote the study's commentary, told National Geographic.

An ethical gray matter

Before anyone gets an Island of Dr. Moreau vibe, it's worth noting that the brains did not approach neural activity anywhere near consciousness.

The BrainEx solution contained chemicals that prevented neurons from firing. To be extra cautious, the researchers also monitored the brains for any such activity and were prepared to administer an anesthetic should they have seen signs of consciousness.

Even so, the research signals a massive debate to come regarding medical ethics and our definition of death.

Most countries define death, clinically speaking, as the irreversible loss of brain or circulatory function. This definition was already at odds with some folk- and value-centric understandings, but where do we go if it becomes possible to reverse clinical death with artificial perfusion?

"This is wild," Jonathan Moreno, a bioethicist at the University of Pennsylvania, told the New York Times. "If ever there was an issue that merited big public deliberation on the ethics of science and medicine, this is one."

One possible consequence involves organ donations. Some European countries require emergency responders to use a process that preserves organs when they cannot resuscitate a person. They continue to pump blood throughout the body, but use a "thoracic aortic occlusion balloon" to prevent that blood from reaching the brain.

The system is already controversial because it raises concerns about what caused the patient's death. But what happens when brain death becomes readily reversible? Stuart Younger, a bioethicist at Case Western Reserve University, told Nature that if BrainEx were to become widely available, it could shrink the pool of eligible donors.

"There's a potential conflict here between the interests of potential donors — who might not even be donors — and people who are waiting for organs," he said.

It will be a while before such experiments go anywhere near human subjects. A more immediate ethical question relates to how such experiments harm animal subjects.

Ethical review boards evaluate research protocols and can reject any that causes undue pain, suffering, or distress. Since dead animals feel no pain, suffer no trauma, they are typically approved as subjects. But how do such boards make a judgement regarding the suffering of a "cellularly active" brain? The distress of a partially alive brain?

The dilemma is unprecedented.

Setting new boundaries

Another science fiction story that comes to mind when discussing this story is, of course, Frankenstein. As Farahany told National Geographic: "It is definitely has [sic] a good science-fiction element to it, and it is restoring cellular function where we previously thought impossible. But to have Frankenstein, you need some degree of consciousness, some 'there' there. [The researchers] did not recover any form of consciousness in this study, and it is still unclear if we ever could. But we are one step closer to that possibility."

She's right. The researchers undertook their research for the betterment of humanity, and we may one day reap some unimaginable medical benefits from it. The ethical questions, however, remain as unsettling as the stories they remind us of.

Scientists see 'rarest event ever recorded' in search for dark matter

The team caught a glimpse of a process that takes 18,000,000,000,000,000,000,000 years.

Image source: Pixabay
Surprising Science
  • In Italy, a team of scientists is using a highly sophisticated detector to hunt for dark matter.
  • The team observed an ultra-rare particle interaction that reveals the half-life of a xenon-124 atom to be 18 sextillion years.
  • The half-life of a process is how long it takes for half of the radioactive nuclei present in a sample to decay.
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