The molecular pathology of neurodegenerative and psychiatric disorders

The proper functioning of the brain relies on the homeostasis of various factors in the central nervous system, where a healthy neural-survival environment is sustained by efficient protein degradation of abnormally accumulated protein aggregates as β-amyloid, hyperphosphorylated-Tau, or α-synuclein, etc., the dysfunction of which might interfere a series of subcellular molecular actions featured by altered mitochondrial metabolism leading to the overproduction of reactive oxygen species, the upscaling of neuroinflammation accompanied by activated astrocytes or microglia, and eventually the onset of various neurological diseases, e.g., Alzheimer's disease, Parkinson's disease, and multiple sclerosis. While for psychiatric disorders, namely schizophrenia and major depressive disorder, significantly different mechanism was suggested that the neurodevelopmental disorders, the alterations in the neural network, or neurotransmitter dysregulation, e.g., dopamine, glutamate, 5-hydroxylamine, and γ-aminobutyric acid, any of which might ultimately result in the imbalance of the excitatory and inhibitory synapses, and the occurrence of such diseases.