Huntington’s Disease and Cannabinoids

Huntington’s disease (HD) is a hereditary neurodegenerative disease in which a mutated protein attacks the nerve cells of the brain. The disease is a progressive disorder in which patients will gradually lose functioning until death, usually from disease complications.1

The symptoms of HD fall under three main categories: movement, cognitive and psychiatric. Symptoms begin with subtle difficulties in coordination to involuntary movements known as chorea and involuntary muscle rigidity and contracture, or dystonia. With disease progression, patients have impaired gait, posture, balance and difficulty with speech or swallowing. Cognitive impairments include lack of impulse control or awareness, slowness in processing thoughts, difficulty organizing or focusing on tasks.1

Most common psychiatric disorder with HD is depression, but also include fatigue, loss of energy and irritability. Currently, there is no cure for HD and treatment is aimed towards symptom management. The activity on the body’s endocannabinoid system and the anti-inflammatory effect of cannabis suggest the use of medical marijuana not only as a natural alternative treatment for patients but also for protective mechanisms against disease progression.

Recent studies have demonstrated a loss of cannabinoid (CB1) receptors in postmortem basal ganglia of HD patients.2

A study was conducted on rats with degeneration of striatal efferent GABA-ergic neurons and loss of CB1 receptors in the basal ganglia, similar to findings in HD patients.2

In this study, administration of substances that increased endocannabinoid activity activated the remaining population of CB1 receptors, resulting in significant improvement of motor disturbances and neurochemical deficits.2

This suggested that substances increasing the endocannabinoid uptake or metabolism may be useful for treating hyperkinetic symptoms of HD. Moreover, researchers at the University of Cordoba developed a cannabinoid compound to test the neuroprotective effects of cannabinoids.3

The compound, cannabigerol (CBG), and its effects were observed in vitro and in mice, and in both exerted an anti-inflammatory and neuroprotective effect.3

CBG also increased the ability to promote survival of the affected neuronal precursors, suggesting the possibility of long term neuron repair.3

Although limited by the regulations of medical marijuana, specific studies have also been conducted evaluating the effects of CBD in human patients with Huntington’s disease for chorea severity and other therapeutic outcome variables. The results concluded that CBD at an average daily dose of 700mg/day for 6 weeks were neither symptomatically effective nor toxic in neuroleptic free patients with HD.4

However, medical cannabis and its tension reducing effects, as well as reduction of anxiety and restlessness, have been proven from numerous studies and may offer relief for HD patients suffering from decreased quality of life.4,5

A systematic literature review was conducted on the effects of medical cannabis on the movement disorder symptoms of HD such as tremors, spasms, spasticity, chorea and sleep quality.5

Outcomes were measured using changes in psychomotor and sleep related symptoms.5

A total of 22 studies were reviewed and showed strong evidence of reported significant improvement in the neurologic symptoms of spasms, tremors, spasticity, chorea and quality of sleep following treatment with medical cannabis.5

Analysis of specific motor symptoms recorded significant improvement after cannabis treatment for tremors and rigidity and an increase in average number of hours slept by HD patients.5

Huntington’s disease is a devastating condition with no known cure and often, patients suffer from unsatisfactory symptom management of the disease. Medical cannabis provides an alternate natural treatment option for patients who suffer from side effects of prescription drugs. Growing research suggests that medical cannabis can not only relieve patients of symptoms and provide an improved quality of life but may also offer potential neuroprotective properties at the pathophysiological level of the disease.

References

Huntington’s disease: Hope through research. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/ Patient-Caregiver-Education/Hope-ThroughResearch/Huntingtons-Disease-Hope-Through.

Lastres-Becker I, Hansen HH, Berrendero

F, et al. Alleviation of motor hyperactivity and neurochemical deficits by endocannabinoid uptake inhibition in a rat model of Huntington’s disease. Synapse. 2002;44(1):23-35. doi:10.1002/ syn.10054

Nuria A. Cannabinoids as Neuroprotectors for Huntington’s disease.

Kalapa Clinic. https://www.kalapa-clinic. com/en/cannabinoids-huntingtons-disease/. Published March 30, 2017.

Consroe P, Laguna J, Allender J, et al. Controlled clinical trial of cannabidiol in Huntington’s disease. Pharmacol Biochem Behav. 1991;40(3):701-708. doi:10.1016/00913057(91)90386-g

Akinyemi, Edward & Randhawa, Gavin & Longoria, Victor & Zeine, Rana. (2020). Medical Marijuana Effects in Movement Disorders, Focus on Huntington Disease; A Literature Review. International Journal of Pharmacy and Pharmaceutical Sciences. 23. 389-395. 10.18433/ jpps30967.