Cannabis and Parkinson's disease

Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's disease. Currently there is no cure for the disease. Could cannabis be useful to protect the brain of these patients or to relieve their symptoms?

Parkinson's disease is a chronic degenerative disease of the central nervous system that mainly affects areas of the brain responsible for the control of movement. It usually appears in people over 60 years of age (although there are cases of so-called juvenile Parkinson's that appear in people under 40) and more in men than in women.

Parkinson's disease is defined by the death of neurons in an area of ​​the brain called substantia nigra, responsible for the production of dopamine, one of the neurotransmitter molecules necessary for signals to travel properly through the brain. This lack of dopamine alters the signaling of that area, the basal ganglia, responsible for the control of movement. That is why the main symptoms of the disease are motor. The characteristic tremor at rest, which everyone associates with the disease, we must add rigidity, postural instability and bradykinesia (slowing of movements). In later stages of the disease may also appear sensory, sleep, affective (depression or anxiety) and, in the later stages, dementia.

Approximately in 5% of the cases, the disease appears as a consequence of the mutation in certain genes. However, in the great majority of patients the cause is unknown, being probably a mixture of genetic susceptibility and environmental factors.

At present there is no cure for the disease and only the symptoms of it are treated. In addition, one of the main treatments, levodopa, which is used to supply the deficiency of dopamine, ceases to be useful after a few years and causes uncontrolled movements (dyskinesias) in patients. This makes it necessary to investigate new compounds that can protect neurons from death caused by this disease and / or alleviate its symptoms.

Given this panorama, could cannabis be useful in the treatment of Parkinson's disease? The use of cannabis for the treatment of Parkinson's disease by William Richard Gowers in his "Manual of diseases of the nervous system" (A Manual of Diseases of the Nervous System) was already described at the end of the 19th century in Europe. Philadelphia, Pa, USA: P. Blakiston's Son & Co; 1888). Let's see what the scientific evidence is 130 years later.