Neurodegenerative Diseases

Neurodegenerative diseases are a class of progressive diseases caused by abnormalities in the structure and function of nerves. This type of disease is characterized by the loss of specific neurons in large numbers, which can lead to cognitive and behavioral disorders, even death in severe cases, and it is very difficult to cure. The incidence of many neurodegenerative diseases will increase with age, and the ever-increasing life expectancy of modern life makes it urgent to develop new and more effective treatment strategies to combat these destructive diseases.

Classification of Neurodegenerative Diseases

Neurodegenerative diseases can be divided into two types: acute neurodegenerative diseases and chronic neurodegenerative diseases. Although the lesions and causes of these diseases are different, with the progress of research, most neurodegenerative diseases have many common characteristics. For example, neuronal degenerative lesions are common to them. These similarities make these diseases interrelated at the subcellular level. The discovery of these similarities offers hope for improvements in the treatment of many diseases simultaneously. The common neurodegenerative diseases are listed as follows:

• Alzheimer's disease (AD)
• Parkinson's disease (PD
• Amyotrophic lateral sclerosis (ALS)
• Huntington disease
• Prion diseases

Causes of Neurodegenerative Diseases

• Oxidative stress. Because free radicals are generated excessively and cannot be removed in a timely manner, the body's oxidation and antioxidant effects are unbalanced, eventually leading to damage to cells and tissues of the body. Free radicals are atoms or groups with unpaired electrons, including hydroxyl radicals (OH•), superoxide anions (O ), nitric oxide (NO), and the like. In recent years, oxidative damage to neural tissue has been found in neurodegenerative diseases such as AD, PD, and ALS.
• Mitochondrial Dysfunction. There are mtDNA defects and oxidative phosphorylation abnormalities in the brain of AD patients. Polymerase chain reaction (PCR) and blot hybridization tests revealed that mtDNA breaks, base deletions, and missense mutations appeared in the brain tissue of patients with sporadic AD. Electron microscopy confirmed that the number of mitochondria was increased, the structure was abnormal, and lamellar and crystalline inclusions appeared. In addition, neuron mitochondrial dysfunction in AD patients will lead to insufficient energy supply to the neurons and release a large amount of ROS, induce oxidative stress damage, imbalance of calcium regulation, and eventually trigger neuronal apoptosis.
• Excitatory toxins. Excessive glutamate concentration in the intercellular space can be toxic to neurons, leading to neuron degradation, aging, and death. This excitotoxic effect of glutamate is closely related to the occurrence and development of various neurodegenerative diseases, and is one of the important mechanisms leading to the death of neurons in neurodegenerative diseases.
• Immune inflammation. Much evidence suggests that inflammation plays an important role in the pathogenesis of AD. The innate immune system has natural immune defense functions formed during germline development and evolution. Compared with another specific immune response of the body, it can respond quickly to various harmful substances to protect the body. The activation of the innate immune system itself is a double-edged sword. Prolonged and uncontrollable stimuli of harmful substances (such as aggregated forms of Aβ), which activate the innate immune system, can have a damaging effect on the brain.

Prevention and Treatment of Neurodegenerative Diseases

Considering the diversity of the causative factors of neurodegenerative diseases, blocking one or two pathways is difficult to reduce neuronal dysfunction and loss. With the continuous deepening of the research on neurodegenerative diseases, the use of multi-path and multi-target treatment can play a good role in the rehabilitation of the symptoms and brain dysfunction of patients with neurodegenerative diseases. On the one hand, the pathological changes that accompany the onset of neurodegenerative diseases are irreversible. When a patient suffers from cognitive impairment, the course of the disease usually reaches the middle to advanced stages. On the other hand, current treatments can only slow the development of the disease, but cannot fundamentally reverse the damage to the neural network. Therefore, for neurodegenerative diseases, early diagnosis and early treatment should be done as far as possible, to prevent further development of the disease.

For research use only. Not intended for any clinical use.