I think everyone is familiar with Parkinson's disease and Alzheimer's disease. Parkinson's  disease (PD) is a common degenerative disease of the nervous system, which is common in the elderly. The average age of onset is about 60 years old, and it is rare in young people under 40 years old. The prevalence rate of PD among people over 65 years old in China is about 1.7%. Most patients with Parkinson's disease are sporadic cases, and less than 10% of patients have family history. The most important pathological change of Parkinson's disease is the degeneration and death of dopaminergic neurons in the substantia nigra of the midbrain, which leads to the significant decrease of Da content in the striatum. The exact cause of this pathological change is still unclear. Genetic factors, environmental factors, aging, oxidative stress and other factors may participate in the degeneration and death process of PD dopaminergic neurons. Its clinical manifestations mainly include static tremor, bradykinesia, myotonia and postural and gait disorders. At the same time, patients may have non motor symptoms such as depression, constipation and sleep disorders.

    Alzheimer's disease, also known as Alzheimer's disease (AD), is a hidden and progressive neurodegenerative disease. Clinically, it is characterized by memory impairment, aphasia, apraxia, agnosia, impairment of visuospatial skills, executive dysfunction, personality and behavior changes, and the etiology is unknown so far. The person who comes on before the age of 65 is called Alzheimer's disease; People who come on after 65 years old are called senile dementia.

    These two diseases often trouble older people and make their children very worried. Therefore, how to prevent the occurrence of these two diseases has always been a hot topic for scholars. China is a big country that produces and drinks tea. Tea has always been a common drink in our daily life. Besides clearing away greasiness, tea also has an unexpected benefit, that is, it can prevent Parkinson's disease and Alzheimer's disease. Green tea contains an important active ingredient epigallocatechin  gallate (EGCG), which is the most effective active ingredient in tea polyphenols and belongs to catechin. A large number of studies have shown thatEpigallocatechin gallateIt can protect the nerve from damage in neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, etc.). Modern epidemiological studies have shown that tea drinking is negatively correlated with the occurrence of some neurodegenerative diseases (such as Parkinson's disease), so it is speculated that tea drinking may activate some endogenous protective mechanisms in neurons. EGCG also has antidepressant effect, and its antidepressant activity is closely related to the interaction of γ - aminobutyric acid receptor. For HIV infected people, viral dementia is one of the pathogenesis. Recent studies have shown that EGCG can block this pathological process.EGCG mainly exists in green tea, but not in black tea. Therefore, a cup of green tea after a meal is often used to clear away greasy oil and maintain health.