Parkinson’s disease is the second most common neurodegenerative disorder in the United States, after Alzheimer’s disease. It’s also the 14th most common cause of death in all age groups. There’s no cure yet for this progressive neurological disorder. Available medications for controlling its symptoms aren’t always effective and can have severe side effects.
But after nearly three decades of sometimes conflicting studies, recent research reveals that cannabis compounds—particularly tetrahydrocannabinol (THC)—can ease not only the well-known motor symptoms of Parkinson’s disease, but also the less obvious ones of pain, depression and loss of senses such as taste, smell and touch. What’s more, marijuana may offer new hope for slowing the progression of the disease itself.
Parkinson’s disease is a chronic neurological disorder characterized by symptoms that include its trademark dyskinesia—the tremors and problems with balance and coordination that make it difficult for Parkinson’s patients to speak, relax or move normally. Parkinson’s patients can also experience varying levels of fatigue, pain and mood-related symptoms such as depression, anxiety and problems concentrating. In advanced stages, dementia can also develop.
All of these symptoms arise from a single underlying cause: a decline in the body’s production of dopamine, a key neurotransmitter that regulates a number of essential physiological and mood-related functions. Dopamine is probably best known as the “feel good” chemical that’s released in large amounts as part of the brain’s pleasure, reward and learning circuits.
But dopamine does much more. When expressed in certain areas of the midbrain, it also plays a major role in the functioning of motor control, balance and coordination. Researchers believe that neurons in the dopaminergic system can become damaged or die, so that over time less and less dopamine is produced. Those declining levels of dopamine are responsible for both the motor and mood-related symptoms of Parkinson’s disease.
Standard Parkinson’s disease treatments aren’t always effective and can have serious side effects. Medications such as Levodopa and Tolcapone work to prevent the breakdown of dopamine in the brain and boost the effects of existing dopamine production, but these drugs can cause complications such as liver failure and an increase in dyskinesia.
Surgical intervention can also be used to reduce Parkinson’s symptoms. Deep brain stimulation can moderate involuntary movement and coordination problems by implanting electrodes into the brain, but this approach brings the usual risks of surgery and may not always be effective.
The effort to find safer and more effective treatment options prompted the earliest research on cannabis to relieve the motor symptoms of Parkinson’s disease, nearly three decades ago.
Research on the connection between cannabis and Parkinson’s disease began in the mid 1990s with a small study on a small group of Parkinson’s patients who used cannabis. That study sought to discover whether cannabis could reduce Parkinson’s dyskinesia, but researchers reported that it failed to show any measurable positive outcomes from marijuana.
In 2004, a larger-scale study was conducted in the Czech Republic, and again, this study reported no significant improvements from cannabis. But in the last decade or so, a number of studies conducted in the U.S., Israel and Europe have focused on the role of the endocannabinoid system in promoting dopamine activity as a way to explore the effects of cannabis on Parkinson’s disease. This kind of research reveals the reasons that the marijuana compounds THC and cannabidiol (CBD) can reduce Parkinson’s symptoms in many people.
The human body has a large network of naturally occurring cannabinoid receptors. These cells respond to the body’s production of natural, or endogenous, cannabinoids—and to the very similar cannabinoids from cannabis, which include THC and CBD. Cannabinoid receptors play a major role in processes such as modulating pain, reducing anxiety and boosting the immune system, and their effects on dopamine production reveals why cannabis can be effective for relieving multiple symptoms of Parkinson’s disease.
Jan Lavelle was diagnosed with Parkinson’s disease a few years ago. Now a wellness consultant, she turned to cannabis as part of a passionate commitment to natural alternatives for managing her symptoms. Speaking with HelloMD, she says she began taking CBD tinctures after a friend recommended it and then developed a protocol for microdosing with other cannabis products including cannabidiolic acid (CBDA) and non-psychoactive tetrahydrocannabinolic acid (THCA).
“Cannabis gives me some relief from my symptoms,” she says. “When you have Parkinson’s you lose your sense of taste and smell, your body kind of freezes up. CBDA and the THCA have actually brought back my sense of taste and smell.”
Jan notes that conventional medications for Parkinson’s disease—pharmaceuticals like Levodopa and Tolcapone—only offer symptom control, not a way to slow or stop the disease. But, she says, “with cannabis, we actually can do something to slow the disease because of the connection between Parkinson’s disease and the endocannabinoid system.”
Pain is a frequent symptom of Parkinson’s disease, so that people experiencing pain might be prescribed additional medications, with their own side effects and risks. But recent studies on cannabis and opioid use have shown that cannabis, particularly CBD, can be so effective in relieving pain that a majority of people using potent opioid painkillers are able to either use fewer of these drugs or stop using them altogether when they take cannabis.
For Parkinson’s disease patients, too, marijuana compounds are able to stimulate the activity of dopamine and the body’s natural opioid receptors to provide relaxation and relief from pain. CBD is also a potent anti-inflammatory, and may help to prevent the neuron damage that leads to Parkinson’s as well.
A well-known effect of cannabis for many people is a feeling of relaxation and calm. And because cannabis compounds can activate receptors in the brain’s pleasure, reward and learning circuits, cannabis can help to relieve the depression and anxiety that can also be hidden symptoms of Parkinson’s disease.
Research on the relationship between cannabis and Parkinson’s disease has a relatively brief history, and early studies were limited and lacked today’s insights into the functions of the endocannabinoid system. But newer research reveals the complex connections between cannabis and the processes that lead to Parkinson’s disease—and provides new hope for relieving its symptoms. “The benefits we get from the whole, healing plant,” says Lavelle, “are endless.”
Photo credit: Nathália Bariani