In recent years, as the knowledge of Parkinson’s disease has become more widespread, the typical Parkinson’s disease manifestations of resting tremor, bradykinesia, and muscle tonus have been well recognized and valued by the public and physicians, in which case a definitive diagnosis and timely treatment often no longer become a problem. However, by the time the above symptoms manifest, up to 50-80% of the dopamine neurons in the midbrain have already died, at which point the best time left for the physician to intervene (block or delay) this pathologic change may have been lost. Therefore, how to provide early warning signals of Parkinson’s disease, and then clarify the diagnosis of Parkinson’s disease as early as possible in order to provide neuroprotective interventions earlier is one of the most hot issues in Parkinson’s disease research. Studies have shown that hyposmia is a common symptom of Parkinson’s disease and is present in up to 70-90% of Parkinson’s disease patients. What’s more, olfactory hyperalgesia is often manifested 3-7 years before the appearance of motor symptoms such as tremor and bradykinesia, and it is currently the most emphasized and most promising early warning signal of Parkinson’s disease. Nowadays, there are various olfactory tests that can detect hyposmia or loss of sense of smell, which are simple and easy to use, and can be well used for the early screening of Parkinson’s disease. Of course, hyposmia also exists in other diseases, and the person undergoing the test should first rule out common diseases such as rhinitis, and also assess the possibility of other diseases (e.g., Alzheimer’s disease, schizophrenia) that may also present with a reduced sense of smell. Therefore, if middle-aged or elderly people have a new onset of hyposmia, which is confirmed by olfactory testing but cannot be explained by other reasons, they need to consider the possibility of Parkinson’s disease at a very early stage, and it is recommended to go to the neurology department of a regular hospital for further examination and judgment. Some patients may require PET functional imaging of the dopamine transporter to help diagnose the disease. For many years, the results of neuroprotective treatment (slowing down the progression of the disease) for Parkinson’s disease have been poor, and one of the important reasons may be that the cases enrolled in the clinical trials were not at a very early stage, and the timing of the intervention was late. However, the results of a recent study published in the prestigious journal New England Medicine suggest that reserpignan (1 mg/day) may slow the progression of Parkinson’s disease. In the future, if Parkinson’s disease can be diagnosed and effectively intervened in a timely manner before motor symptoms (e.g., decreased sense of smell) are manifested, it is entirely possible to achieve unanticipated better results and bring more help to the majority of patients.