In a controlled study involving mice, researchers found that a specific synthetic cannabis reduced essential tremor, a potentially groundbreaking finding for a condition that impacts 10 million people in the United States alone.

Researchers at the University of Copenhagen in Denmark conducted the study and published their findings in the journal Nature Neuroscience. 

Essential tremor is a neurological disorder that causes involuntary and rhythmic shaking. While it can impact any part of the body, it typically manifests in people’s hands and is most noticeable when they try to do simple tasks such as drinking from a glass or tying a shoelace.

While not dangerous on its own, the condition worsens over time and can make day-to-day life extremely difficult for some. Essential tremor is a separate condition from Parkinson’s disease, which also causes tremors. The condition typically first appears in people over 40.

“We have focused on the disease essential tremor. It causes involuntary shaking, which can be extremely inhibitory and seriously reduce the patient's quality of life,” Associate Professor Jean-François Perrier, who headed the research project, said in a news release. “However, the cannabinoid might also have a beneficial effect on sclerosis and spinal cord injuries, for example, which also cause involuntary shaking.” 

Cannabis activates an important group of cells called astrocytes.

The key to the research is the focus on astrocytes, which are cells in the spinal cord and brain. In the study, the researchers demonstrated that cannabis had the ability to activate these cells.

That’s vital because astrocytes release a substance in the spinal cord and brain called adenosine that reduces nerve activity. That reduction in nerve activity is what led to the reduction in shaking for the mice.

The researchers used a specific type of synthetic cannabinoid called WIN55,212-2, which they injected directly into the spinal cord. The Denmark researchers focused on the spinal cord because activated spinal cord neurons led to both voluntary and involuntary movements. The shaking that occurs with essential tremors happens when motor neurons simultaneously send conflicting signals. Cannabis greatly reduced that activity. 

What does this mean for those who have essential tremor?

The approach taken by the University of Copenhagen researchers marked a new direction on this use of cannabis. Previous studies had not focused on astrocytes. The next step for researchers is to set up a clinical study involving human patients with essential tremors.

Postdoc Eva Maria Meier Carlsen with the university’s Department of Neuroscience, Faculty of Health and Medical Sciences, said in the news release that “one might imagine a new approach to medical cannabis for shaking, where you -- during the development of cannabis-based medicinal products -- target the treatment either at the spinal cord or the astrocytes -- or, at best, the astrocytes of the spinal cord.”

Carlsen also pointed out that the treatment does not impact brain neurons responsible for memory and cognitive abilities, meaning patients could get treatment for essential tremors without any worrying side effects.