Huntington's Disease Awareness Month
In honor of our patients with Huntington’s Disease and for highlighting recent clinical trials, we have gathered information about the disease and recent clinical trials which have looked at cannabinoid therapy as a possible and promising treatment option for patients with HD.
Huntington’s Disease is a genetic disorder that causes the progressive breakdown of nerve cells in the brain. It deteriorates a person’s physical and mental abilities during their prime working years, and has no known cure. Every child of a parent with HD has a 50/50 chance of carrying the faulty gene. Today, there are approximately 30,000 symptomatic Americans and more than 200,000 at-risk of inheriting the disease.
Many describe the symptoms of HD as having ALS, Parkinson’s and Alzheimer’s—simultaneously.
Symptoms usually appear between the ages of 30-50, and worsen over a 10 to 25 year period. Ultimately, the weakened individual succumbs to pneumonia, heart failure, or other complications. Everyone has the gene that causes HD, but only those that inherit the expansion of the gene will develop HD and perhaps pass it on the each of their children. Every person who inherits the expanded HD gene will eventually develop the disease. Over time, HD affects the individual’s ability to reason, walk, and speak.
· Personality changes, mood swings, and depression
· Forgetfulness and impaired judgement
· Unsteady gait and involuntary movements
· Slurred speech, difficulty in swallowing, and significant weight loss
Medications are available to help manage the symptoms of Huntington’s disease, but treatments can’t prevent the physical, mental, and behavioral decline associated with the condition.
Huntington’s disease is caused by an inherited defect in a single gene. Huntington’s disease is an autosomal dominant disorder, which means that a person needs only one copy of the defective gene to develop the disorder. So in a family with only a single parent carrying the defective gene will result in all the children having 50% chance of inheriting the gene that causes the disease.
Effects of cannabis-based treatment for Huntington’s Patients:
Research has shown that cannabis helps slow the progression of HD through its interaction with the endocannabinoid system. After studies determined that HD was related to a loss of cannabinoid receptors in the basal ganglia, researchers set out to examine whether increasing activity could be therapeutically beneficial for treating the disease.
In pre-clinical trials, the major cannabinoids found in cannabis have been found to be effective at protecting the life of neurons in the brain. Research has shown that through the activation of cannabinoid 2 receptors (CB2), the inflammation and toxicity of microglial cells is reduced, which in turn slows the neurodegeneration caused by Huntington’s Disease. Through the activation of cannabinoid 1 receptors (CB1), cannabinoids have shown to effectively alleviate specific motor symptoms like tremors and movement disorders and reduce the process in which neurons are damaged and killed to slow the progression of the disease.
Studies examining the effect of cannabis-based medications on Huntington’s disease have proven cannabinoids effective at delaying the progression of HD.
Targeting the endocannabinoid system with cannabinoids may have a potential therapeutic benefit for treating basal ganglia disorders like Parkinson’s Disease and Huntington’s Disease. Cannabinoids are effective at providing neuroprotection through three methods: reducing inflammation by activating CB2 receptors, limiting cell death by activating CB1 receptors, and providing an antioxidant effect through a mechanism independent of cannabinoid receptors.
Researchers from the Ramon y Cajal University Hospital’s Foundation for Biomedical Investigation in Madrid have recently completed the first ever clinical trial to investigate a cannabis extract as a treatment for Huntington’s Disease.
The genetic mutation in HD causes damage to the striatal and cortical neurons, putting neuroprotective drugs at the forefront of HD research. Initial research has shown that cannabidiol (CBD), a non-psychoactive component of the cannabis oil, displays neuroprotective effects in mice with similar conditions to the disease, but scientists don’t know how it exactly works.
Experimental evidence showed researchers that CBD aids neurons with its antioxidant properties. Though CBD and THC are almost identical molecules, CBD’s arrangements allows it to be a powerful antioxidant that is also safe and tolerable at high doses in humans. THC is not as powerful an antioxidant, but it interacts strongly with cannabinoid receptors, unlike CBD which interacts with the endocannabinoid system in a more complex and indirect manner.
In a later experiment, CBD and THC administered together at equal ratios, also caused similar but enhanced neuroprotective effects to CBD alone, meaning that something else must be at play that involve cannabinoid receptors themselves, not just the benefits of a neural antioxidant. The endocannabinoid system is intricately tied to the progression of Huntington’s Disease. Researchers have discovered that early on in the disease, cannabinoid receptors disappear massively in striatal neurons.
The recent clinical trial by Ramon y Cajal University Hospital’s Foundation for Biomedical Investigation and in collaboration with GW Pharmaceuticals (makers of the cannabis formulation Sativex), was the first ever to use cannabis in Patients with HD.
Overall, the research that has been done to show the effects of medical cannabis and cannabinoid therapy, with Huntington’s Disease is very promising as a treatment option for patients. The neuroprotective benefits of cannabinoids, and the link between fewer cannabinoid receptors in people with HD, is very likely to be a target for future research, trials, and eventually as well-known and wide-practiced treatment option. As long as marijuana is classified as a Schedule I drug, the United States will not be able to conduct large scale clinical trials. However, the results in clinical trials overseas are very promising and hopeful.
Huntington’s Disease Society of America
Huntington’s Disease-- Mayo Clinic
Neuroprotection by Cannabinoids in huntington’s Disease
Huntington’s Disease-- Medical Marijuana Research Overview