Cannabis and Movement Disorders
Movement disorders and neuro-degenerative diseases, which are sometimes interlinked, are among the conditions cannabis is particularly well suited to treat.
The therapeutic use of cannabis for treating muscle problems and movement disorders has been known to western medicine for nearly two centuries. In 1839, Dr. William B. O’Shaughnessy noted the plant’s muscle relaxant and anti-convulsant properties, writing that doctors had “gained an anti-convulsive remedy of the greatest value.” In 1890 Dr. J. Russell Reynolds, physician to Queen Victoria, noted in an article in The Lancet that for “organic disease of a gross character in the nervous centers . . . India hemp (cannabis) is the most useful agent with which I am acquainted.”
Muscular spasticity is a common condition, affecting millions of people in the United States. It afflicts individuals who have suffered strokes, as well as those with multiple sclerosis, cerebral palsy, paraplegia, quadriplegia, and spinal cord injuries. Conventional medical therapy offers little help for spasticity problems. Phenobarbital and diazepam (Valium) are commonly prescribed, but they rarely provide complete relief, and many patients develop a tolerance, become addicted, or complain of heavy sedation. These drugs also cause weakness, drowsiness and other side effects that patients find intolerable.
Extensive modern studies in animals and various clinical states have shown that cannabis can treat movement disorders affecting older patients, such as tremors and spasticity, because cannabis has antispasticity, analgesic, antitremor, and antiataxia actions.[98-110]
In the federal court brief they filed in support of physicians’ right to recommend cannabis, the American Public Health Association stated that “Marijuana is effective in treating muscle spasticity.” They point out that the government’s own Institutes of Medicine report on medical use of cannabis found that “current treatments for painful muscle spasms . . . have only limited effectiveness and their use is complicated by various adverse side effects.” They go on to note that “a survey of British and American MS patients reports that after ingesting marijuana a significant majority experienced substantial improvements in controlling muscle spasticity and pain. An extensive neurological study found that herbal cannabis provided relief from both muscle spasms and ataxia (loss of coordination), a multiple benefit not achieved by any currently available medications” (amicus brief in Conant v. McCaffrey, 2001 filing).
Cannabis also has enormous potential for protecting the brain and central nervous system from the damage that creates various movement disorders. Researchers have found that cannabinoids fight the effects of strokes, as well as brain trauma, spinal cord injury, and multiple sclerosis. More than 100 research articles have been published on how canna-binoids act as neuroprotective agents to slow the progression of such neurodegenerative diseases as Huntington’s, Alzheimer’s and particularly Parkinson’s, which affects more than 52% of people over the age of 85.
The contemporary understanding of the actions of cannabis was spurred by the discovery of an endogenous cannabinoid system in the human body. This system appears to be intricately involved in normal physiology, specifically in the control of movement.[111-115] Central cannabinoid receptors are densely located in the basal ganglia, the area of the brain that regulates body movement. Endogenous cannabinoids also appear to play a role in the manipulation of other transmitter systems within the basal ganglia—increasing transmission of certain chemicals, inhibiting the release of others, and affecting how still others are absorbed. Most movement disorders are caused by a dysfunction of the chemical loops in this part of the brain. Research suggests that an endo-genous cannabinoid tone participates in the control of movements.[116-120]
Endocannabinoids have paradoxical effects on the mammalian nervous system: Sometimes they block neuronal excitability and other times they augment it. As scientists are developing a better understanding of the physiological role of those natural cannabinoids, or endocannabinoids, it is becoming clear that these chemicals may be involved in the pathology of several neurological diseases. Researchers are identifying an array of potential therapeutic targets within the human nervous system. They have determined that various cannabinoids found in the cannabis plant interrupt the synthesis, uptake or metabolism of the endocannabinoids that drive the progression of Huntington’s disease, Parkinson’s disease, and tremor.[121-122]
Parkinson’s disease has been linked to dysfunction in the body’s dopamine system, specifically the production of too much of the neurotransmitter glutamate and oxidative damage to dopaminergic neurons. Studies have found a tight association between cannabinoids and dopamine, and recent research has produced anatomical, biochemical and pharmacological evidence supporting a role for the endogenous cannabinoid system in the modulation of dopaminergic transmission. Cannabinoid receptors switch between blocking and enhancing dopamine signaling. Cannabinoids neuroprotective action appears to result from their ability to inhibit reactive oxygen species, glutamate and tumour necrosis factor.
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