Cognitive Dysfunction in Parkinson’s Disease: A Traditional Medicine Therapeutic Approach

Abstract

Ernest Dalle, Marc O Ondoua Nguele, Herve Narcisse Bayaga and Frederic Melaman Sego

Background: Parkinson’s disease (PD) is an incurable complex neurodegenerative disease pathologically described with a six- stage alpha-synucleinopathy. In stage 4 of the disease, the toxic alpha-synuclein reaches the hippocampus and causes a decline in one or more cognitive abilities, including memory, attention, speech, or visual-spatial ability. Cognitive dysfunction is increasingly recognized among the most important pre-motor symptoms associated with PD, which can severely affect the patient’s quality of life. Furthermore, this pre-motor symptom of PD shares many common pathophysiological mechanisms with oxidative stress, cytotoxicity, or neuro-inflammation in specific individuals. Objective: To highlight the mechanisms of selected traditional medicine therapeutic approaches underlying the prevention and/ or treatment of PD associated with cognitive functions. Methods: Popular traditional herbal compounds, herbal medicines, herbal formulations, or traditional medicine active ingredients that have been reported to have promising prospects for the prevention and/or cure of PD associated with cognitive deficits were reviewed, and their mechanism of action was pinpointed. Considering the wearing-off effects of most “Western” medicines, for each selected traditional medicine (plants/plant extracts, leaves, or roots), the beneficial bioactive compounds were reported. Results: Bioflavonoid compounds among medicinal plants have a potential antioxidant capacity on selective dopaminergic neurons. Targeting bioactive compounds with selective affinity to the ultrastructure of the substantia nigra neurons, the cerebral cortex, or the hippocampus reduces mitochondrial damage and alleviates PD-associated with non-motor symptoms. Tetrandrine is a promising traditional therapeutic alternative for blocking the neurotoxic effects of conventional anti-PD drugs. The neuroprotective effect of Curcumin on dopaminergic neurons is related to its activity as an anti-inflammatory promoter in the expression of a sort of “enzyme” that accelerates the formation of substances that cause neuroinflammation in the brain of patients with PD. Medicinal plant extracts with anti- or pro-apoptotic effects are good candidates to significantly regulate the neuronal cell division cycle that prompts behavioral and clinical signs of PD. Conclusion: Medicinal plant extracts may combat cognitive deficits in PD through the inhibition of oxidative stress, the regulation of mitochondrial dysfunction, the reduction of toxic excitatory compounds, the inhibition of neuro-inflammation, the inhibition of neuronal apoptosis, and the inhibition of abnormal protein aggregation in the brain.

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