CBD makes glaucoma worse, researchers find

A new study reveals that it increases eye pressure, negating the effects of THC.

  • For decades, marijuana has been touted as providing glaucoma relief.
  • A study out of Indiana University shows that while THC reduces eye pressure, CBD does the opposite.
  • Of the 18 mice tested, females were less responsive to marijuana than males.

While glaucoma has been the butt of many well-intentioned, wink-wink weed jokes for decades, the disease is quit serious. In fact, glaucoma is the leading cause of blindness in people above sixty. Glaucoma is insidious as well. Abnormally high pressure in your eyes gradually damage the optic nerve.

Vision loss is subtle until it reaches advanced stages, by which point there is little chance of slowing damage. By this point prevention is impossible.

It begins with patchy spots in your vision, mostly in the periphery or central vision. By the time glaucoma is in latter stages, tunnel vision results. Deterioration of the optic nerve is irreversible. Some treatments mitigate damage by lowering eye pressure, such as laser treatment and eye drops.

And, of course, there is marijuana, which does, in fact, lower eye pressure — specifically, THC lowers it. But there are trade-offs. Unlike other treatments, marijuana's effects last 3–4 hours, meaning you need to smoke continuously throughout the day. While pressure is reduced, the constant smoke creates other problems.

However, a new study out of Indiana University reveals that marijuana, specifically cannnabidiol (CBD), can make glaucoma worse.

The study, published in Investigative Ophthalmology & Visual Science on December 14, found that CBD — one of the hottest and, as I've previously written, suspect health trends being shoved into every product imaginable at a premium — actually creates a rise in eye pressure, the exact opposite effect a glaucoma sufferer desires.

Associate scientist Alex Straiker, who led the study, continues:

This study raises important questions about the relationship between the primary ingredients in cannabis and their effect on the eye. It also suggests the need to understand more about the potential undesirable side effects of CBD, especially due to its use in children.

As mentioned, THC indeed lowers eye pressure, which has been the mechanism by which treatment has been administered thus far. The problem is, according to Straiker's research, CBD blocks the pressure-reducing effects that THC offers.

Illustration of glaucoma treatment using ultrasound. The ultrasound beams enable the ciliary body, the gland which produces aqueous humour, to coagulate, reducing the secretion long-term. The optic nerve is no longer under pressure, sight is maintained. Image source: BSIP / UIG via Getty Images

Which makes the science even more paradoxical and troubling for patients: CBD is being advertised as the non-psychoactive wunder drug counterpart to THC, which is what makes you high. Those who crave the benefits of marijuana without the fuzzy feeling find relief in CBD oils, tinctures, and creams. These, however, apparently will not help those with glaucoma because its greatest bioavailability comes from smoking.

It should be noted that this study was conducted on 18 mice. Interestingly, female mice were less affected by THC, which also has implications for marijuana's role in treating glaucoma. More research will have to be conducted on humans, but as Straiker concludes, this research offers new avenues of inquiry.

There were studies over 45 years ago that found evidence that THC lowers pressure inside the eye, but no one's ever identified the specific neuroreceptors involved in the process until this study. These results could have important implications for future research on the use of cannabis as a therapy for intraocular pressure.

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Are modern societies trying too hard to be clean, at the detriment to public health? Scientists discovered that a microorganism living in dirt can actually be good for us, potentially helping the body to fight off stress. Harnessing its powers can lead to a "stress vaccine".

Researchers at the University of Colorado Boulder found that the fatty 10(Z)-hexadecenoic acid from the soil-residing bacterium Mycobacterium vaccae aids immune cells in blocking pathways that increase inflammation and the ability to combat stress.

The study's senior author and Integrative Physiology Professor Christopher Lowry described this fat as "one of the main ingredients" in the "special sauce" that causes the beneficial effects of the bacterium.

The finding goes hand in hand with the "hygiene hypothesis," initially proposed in 1989 by the British scientist David Strachan. He maintained that our generally sterile modern world prevents children from being exposed to certain microorganisms, resulting in compromised immune systems and greater incidences of asthma and allergies.

Contemporary research fine-tuned the hypothesis, finding that not interacting with so-called "old friends" or helpful microbes in the soil and the environment, rather than the ones that cause illnesses, is what's detrimental. In particular, our mental health could be at stake.

"The idea is that as humans have moved away from farms and an agricultural or hunter-gatherer existence into cities, we have lost contact with organisms that served to regulate our immune system and suppress inappropriate inflammation," explained Lowry. "That has put us at higher risk for inflammatory disease and stress-related psychiatric disorders."

University of Colorado Boulder

Christopher Lowry

This is not the first study on the subject from Lowry, who published previous work showing the connection between being exposed to healthy bacteria and mental health. He found that being raised with animals and dust in a rural environment helps children develop more stress-proof immune systems. Such kids were also likely to be less at risk for mental illnesses than people living in the city without pets.

Lowry's other work also pointed out that the soil-based bacterium Mycobacterium vaccae acts like an antidepressant when injected into rodents. It alters their behavior and has lasting anti-inflammatory effects on the brain, according to the press release from the University of Colorado Boulder. Prolonged inflammation can lead to such stress-related disorders as PTSD.

The new study from Lowry and his team identified why that worked by pinpointing the specific fatty acid responsible. They showed that when the 10(Z)-hexadecenoic acid gets into cells, it works like a lock, attaching itself to the peroxisome proliferator-activated receptor (PPAR). This allows it to block a number of key pathways responsible for inflammation. Pre-treating the cells with the acid (or lipid) made them withstand inflammation better.

Lowry thinks this understanding can lead to creating a "stress vaccine" that can be given to people in high-stress jobs, like first responders or soldiers. The vaccine can prevent the psychological effects of stress.

What's more, this friendly bacterium is not the only potentially helpful organism we can find in soil.

"This is just one strain of one species of one type of bacterium that is found in the soil but there are millions of other strains in soils," said Lowry. "We are just beginning to see the tip of the iceberg in terms of identifying the mechanisms through which they have evolved to keep us healthy. It should inspire awe in all of us."

Check out the study published in the journal Psychopharmacology.