Parkinson’s disease is not Alzheimer’s. Parkinson’s disease, also known as tremor palsy, is a common neurodegenerative disease. It is most common in the elderly, with an average age of onset of around 60 years. Its clinical manifestations are mainly resting tremor, bradykinesia, myotonia and postural gait disorders, often accompanied by depression, constipation, cognitive impairment, sleep disorders, sensory disorders such as smell, autonomic dysfunction and so on. Non-motor symptoms. The pathology of Parkinson’s disease is characterized by degeneration and apoptosis of dopaminergic neurons in the substantia nigra of the midbrain, causing a significant decrease in striatal dopamine. About 24% – 31% of Parkinson’s patients may develop dementia more than one year after the onset of the disease, which is called Parkinson’s disease dementia. Parkinson’s disease dementia is characterized by dementia appearing after Parkinson’s syndrome, with more than 2 items of executive dysfunction, decreased attention span, visuospatial ability, and memory deficits, and severely affecting the ability to perform activities of daily living. Alzheimer’s disease is a degenerative disease of the central nervous system with insidious onset and continuous progressive development. The main manifestations are memory impairment, executive dysfunction, reduced language ability, behavioral changes, and impairment of visuospatial skills. Parkinson’s disease and Alzheimer’s disease are two completely different diseases. Although dementia can occur in some Parkinson’s patients, the etiology, clinical manifestations, and pathological changes of the two are different.