Cannabinoids in the treatment of Parkinson's Disease

Although more clinical trials are needed to confirm the long-term benefits, CBD (cannabidiol) represents a potential new approach to treating Parkinson’s disease. Studies suggest that cannabinoids may not only alleviate motor symptoms but also protect neurons against degeneration, improving patients’ quality of life with fewer adverse effects than conventional therapies.

Parkinson's disease (PD) is a chronic, progressive neurodegenerative disease and one of the most common in the world, characterized by motor symptoms such as tremors, rigidity and bradykinesia (slowness of movement). This pathology results primarily from the degeneration of dopaminergic cells located in the substantia nigra of the brain, leading to a significant reduction in the levels of dopamine, a neurotransmitter essential for motor control (Jankovic, 2008).

It is estimated that between 7 and 10 million people worldwide are affected by this condition, being particularly prevalent among individuals over 60 years of age, although it can occur before the age of 50 in about 5% of cases, as in genetic forms of the disease (Tysnes & Storstein, 2017).

Symptoms

Symptoms of Parkinson's disease vary from person to person and may include:

• Bradykinesia/Dyskinesia: Involuntary, reduced or excessive movements.
• Resting tremor: Tremors that occur when muscles are at rest and usually disappear with movement.
• Muscle rigidity: Increased resistance to passive movement of the limbs and trunk.
• Postural instability: Difficulty maintaining balance, associated with slow movements.
• Non-motor symptoms: These include autonomic dysfunctions, sleep disturbances, constipation, urinary dysfunctions, and cognitive problems such as depression and anxiety (Kalia & Lang, 2015).

Causes

The causes of Parkinson's disease are not yet fully understood, although genetic and environmental factors have been implicated. Certain genetic mutations, such as those in the LRRK2 and PARK7 genes, have been associated with the development of the disease.

Exposure to environmental toxins, such as pesticides, has also been correlated with an increased risk of developing the disease (Kouli et al., 2018). Furthermore, aging is a significant risk factor, as cellular and neuronal functions, including dopamine production, decline with age (Jankovic, 2008).

Recent studies also point to dysbiosis — or an imbalance in the intestinal flora, caused by the reduction of beneficial bacterial species in the microbiota and often accompanied by the proliferation of bacterial species that are harmful to our well-being — as one of the causes of this type of disease.

Treatment

Currently, treatment for Parkinson's disease focuses on relieving symptoms, as there is currently no cure for the disease. First-line therapy includes the administration of levodopa, a precursor of dopamine, which effectively relieves motor symptoms but can lead to the development of dyskinesias (involuntary movements) over time (Olanow et al., 2009).

In recent years, cannabinoids, particularly cannabidiol (CBD), have been studied for their therapeutic potential in alleviating the symptoms of Parkinson's disease. CBD, a non-psychotropic compound from the cannabis plant, has demonstrated neuroprotective and antioxidant properties that may help protect dopaminergic neurons from cell death, slowing the progression of the disease (Garcia et al., 2015).

A clinical study conducted by Zuardi et al. (2009) investigated the effects of CBD in PD patients who presented with levodopa-induced psychotic symptoms. The results showed a significant reduction in psychotic symptoms without negative impact on the patients' motor function. Subsequently, a study by Chagas et al. (2014) demonstrated that the administration of CBD significantly improved the quality of life and general well-being of Parkinson's patients. Other studies confirm that CBD has the potential to reduce levodopa-induced dyskinesia, in addition to improving muscle stiffness and providing better motor control (Müller-Vahl et al., 1999).

Mechanism of Action of Cannabinoids in Parkinson's Disease

Cannabinoids act on CB1 and CB2 receptors located in the basal ganglia, brain regions involved in motor control. In addition, they have an antioxidant role, protecting neurons from degeneration (Garcia et al., 2015). Studies suggest that, in combination with conventional treatments such as levodopa, cannabinoids may provide a new therapeutic approach for the treatment of Parkinson's disease, reducing side effects and potentially slowing the progression of the disease (Sevcík & Masek, 2000).

Clinical trials continue to explore the role of cannabinoids in the treatment of movement disorders, with promising results in terms of reducing tremors and stiffness, without the adverse side effects often associated with conventional pharmacological treatments (Garcia et al., 2015; Müller-Vahl et al., 1999).

Conclusion

While conventional treatment for Parkinson’s disease, such as levodopa, remains the mainstay of therapy, cannabinoids, especially CBD, have emerged as a promising complementary option. Studies suggest that cannabinoids may not only alleviate motor symptoms but also protect neurons against degeneration, improving patients’ quality of life.

Although more clinical trials are needed to confirm long-term benefits, CBD and other cannabinoids represent a potential new approach to treating Parkinson's disease, with fewer adverse effects than conventional therapies (Chagas et al., 2014).

REFERENCES

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