Therapeutic Effects of Capsaicin on Central Nervous Disorders with Special Emphasis on Parkinson’s and Alzheimer’s Diseases

The two major neurodegenerative diseases, viz., Parkinson’s disease (PD) and Alzheimer’s disease (AD), are incurable so far. These diseases are even difficult to manage as their exact pathogenesis is not clear, and currently the drugs that are being used for their management are just for symptomatic relief. At present, pathological pathways for these diseases are being explored at the molecular level, so that effective drugs can be discovered for the specific molecular targets. Recently, capsaicin (CAP) has been found to be effective in ameliorating some of the root causes of AD and PD, targeting some similar and some different mechanisms of action. In case of PD, dopaminergic neurons are lost and it has been found that CAP being a transient receptor potential vanilloid subtype 1 (TRPV1) agonist can help in the treatment of PD as it can further reduce oxidative stress and metabolic impairments of α-synuclein and inhibit glial activation and inflammation, protecting dopaminergic neurons in the striatum and substantia nigra. On the other hand, in the case of AD, amyloid-β (Aβ) accumulation is majorly reported to be responsible for the disease. It is suggested that inducing autophagy of Aβ can improve neural signaling in the brain. The CAP molecule has been explored for this action and has been found to attenuate Aβ amyloid, to improve locomotion, alleviating cognitive impairment. Research indicates that capsaicin, also has potential in combating one of the precursors to Alzheimer’s disease, ischemia. This suggests that it might contribute in reducing the symptoms associated with the condition. It was also found to decrease proinflammatory responses and oxidative stress in various AD models. Thus, it can be suggested that CAP may be utilized as a potential drug molecule against the two neurodegenerative disorders. The present chapter discusses the basic mechanisms behind these two diseases and further details on the role of capsaicin in their amelioration. In addition, certain limitations related to the therapeutic uses of CAP have been discussed.