Mad Cow Disease, more properly known as Creutzfeldt-Jakob Disease (CJD), is a horrific, degenerative brain disease that is fatal in 100% of cases. CJD is caused by prions, which are malformed protein molecules—and there is some evidence that cannabis could work to counteract their effects.
There are several forms of CJD. The most infamous of all is variant CJD (vCJD), a subtype that is thought to occur as a result of eating beef infected with Bovine Spongiform Encephalitis (BSE). A similar prion disease known as kuru is transmitted through cannibalism of human flesh, and until recently was endemic in tribal areas of Papua New Guinea, although it is now all but extinct.
However, vCJD makes up only a tiny fraction of CJD cases overall. Cases of vCJD occurring as a result of eating contaminated beef began to appear in Europe in 1996, particularly in the UK where 177 total cases have now been recorded, but have diminished dramatically since 2000 due to changes in agricultural practice. In total, there have been approximately 300 reported cases of vCJD worldwide.
Classic CJD is more common—although, at a prevalence of approximately one case per year per million people, it is still extremely rare. Classic CJD may occur due to a hereditary genetic mutation, and if so is classed as familial CJD (fCJD). fCJD makes up 15% of all cases of classic CJD; the other 85% arise spontaneously through an unknown mechanism or mechanisms.
It’s possible that consumption of infected meat could lead to classic CJD as well as to vCJD, but this hasn’t been fully established. Currently, it seems more likely that most cases occur as a result of the normal protein-folding process spontaneously going awry.
To understand how CJD affects the brain, we first need to understand some of the basic science behind protein formation and folding. Basically, proteins are very long molecules that are so complex that they fold into three-dimensional structures, which can easily be seen with an electron microscope.
The structure they fold into is determined by interactions between the protein itself and other surrounding proteins and amino acids. Due to the complexity of the interactions and the forces that govern them, there are often multiple possible ways for the protein to fold. Sometimes, these folds can be incorrect, and can render the protein effectively useless and unable to fulfill its usual biological function. These proteins can then build up in various bodily tissues, and if they accumulate in the brain, they can break down brain tissue and cause a rapid decline to death. Interestingly, just one type of protein (now appropriately known as prion protein) is thought to be the common cause of scrapie, BSE, CJD, and other similar diseases (which collectively are known as transmissible spongiform encephalopathies or TSEs).
All it takes for a prion disease to take hold is the presence of a single “seed”: a chain of malformed protein, which can consist of as little as 28 individual protein molecules. These seeds may be produced spontaneously, or may be introduced by consumption of infected meat or receipt of contaminated blood or tissue from an infected donor.
Then, every time the seed encounters an unfolded protein strand, it can influence it to fold incorrectly. The newly-influenced, misfolded offspring of the original seed can then cause other unfolded proteins to misfold, leading to an exponential chain reaction to which no remedy is currently known.
A couple of years ago in late 2013, there was a brief flurry of internet activity regarding cannabis’ ability to counteract the effects of prions in the brain. Almost immediately afterwards, there was another brief flurry of indignant responses to the original claim, which mostly stated that there was little or no validity to it. So what’s the truth of the matter? Let’s take a little look and find out.
There’s actually only one piece of original research which investigates the ability of cannabis or cannabis-related compounds to counteract the effects of prion accumulation. In this study, published in 2007, researchers infected mice with scrapie (a prion disease originally found in sheep, and which is known to be related to BSE found in cattle) and then treated them with THC, CBD, anandamide, 2-AG, and two synthetic cannabinoids.
The researchers found that, uniquely among the cannabinoid compounds tested, CBD showed statistically significant ability to delay the onset of symptoms, and also to delay the overall time of death. This effect was apparent when mice were treated immediately upon infection, and also when treatment commenced 30 days after infection. However, CBD did not significantly delay death when commenced at 120 days after infection.
In the brains of CBD-treated mice, prions were barely detectable, although “substantial amounts” were present in the brains of infected mice that were not treated with CBD. The researchers also noted no side-effects from the administration of CBD, and concluded that CBD could represent a promising candidate for future research into prion disease, due to its low toxicity, lack of psychoactivity and negative side-effects, its neuroprotective and anti-inflammatory properties, and its newly-demonstrated ability to counteract prion accumulation.
The researchers also noted that CBD easily crosses the blood-brain barrier, meaning that it has the potential to be effective even after prion infection reaches the central nervous system.
Not so fast. The problem that so many well-meaning proponents of cannabis medicine and legalization had was to make the mistake of thinking that a single piece of research constitutes medical fact. One would expect that, if research was truly promising and of potential value, at least one or two follow-up studies would be published in the (almost ten) years subsequent to initial publication. But thus far, no positive response to the study has materialized; although there have been several notable negative responses.
An interesting blog post on the subject can be found here. In it, the author points out various flaws in the original study, and criticizes the overall conclusion that CBD is really likely to be effective at all in the treatment of human prion disease.
The author states that these last two points are particularly relevant, as even if CBD could be shown to be effective at controlling the proliferation of prions in the body cavity in the early stages of an infection, that does not extrapolate to being able to counteract the much higher levels of prions that will have built up in a human brain by the time a TSE is diagnosed.
And from the study itself, the lack of effectiveness when treatment commenced later, at 120 days compared to 30, does imply that CBD may not be at all effective against late-stage prion diseases.
Although there are indeed several flaws with the study, there is at least some evidence that CBD could present an important neuroprotective effect. The neuroprotective ability of CBD has been demonstrated on multiple occasions, and there may well be considerably benefit to be derived from using CBD as a dietary supplement throughout the course of one’s life, in order to protect against potential future neurological diseases, including prion disease. After all, the ability of CBD to cross the blood-brain barrier, and the fact that no prions were found in the brains of infected and CBD-treated mice (but were found in infected and CBD-untreated mice), implies strongly that CBD does indeed have the ability to prevent prions from entering the brain from the body cavity, as long as it is present close enough to the initial time of infection.
What the study does not demonstrated is that CBD can be effective in human prion diseases after they have been diagnosed. The findings of the study imply that this would not be the case, as CBD ceases to become effective by 120 days after infection, and human prion diseases are typically not diagnosed until the disease is already very advanced. Thus, not much has changed in the world of CJD research as a result of this finding, and several other drugs have been investigated more recently that exhibit more promising initial signs.
However, the study certainly adds to the already-substantial body of research that supports the neuroprotective effect of CBD. Given CBD’s near-total lack of side-effects, the case for using it as a regular dietary supplement to confer some protection against future neurological diseases may be extremely advantageous and practically without risk.
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