The Role of Thyroid Hormones in Neurodegenerative Disorders: Opportunities and Challenges

Thyroid hormone (TH) is crucial to maintaining nervous system's normal function and is essential for formation of dendrites, axons, and myelin sheaths of neurons, which form the basis for transmitting messages between neurons, and the deficiency of TH affects their development, which in turn affects nervous system's normal operation. Recent articles have found that TH deficiency or abnormal levels not only affect mood and cognitive function but are also closely related to the development of a series of neurodegenerative disorders, like Alzheimer's, Parkinson's and Huntington's diseases, along with multiple sclerosis. The pathologic mechanisms of such diseases are complex, and it is difficult to confirm clinical diagnosis, and there exists a shortage of valid therapies, which can greatly reduce patients' life quality once they develop. Therefore, a deep comprehension of TH mechanism in neurodegenerative disorders and exploring factors affecting its relationship with neurodegenerative disorders are of great clinical and research value. This article reviews the research progress in this field so far, analyzes the functional changes of TH in neurological pathological states, and explores its potential in clinical applications, aiming to provide new orientation for neurodegenerative disorders' future diagnosis and therapy, and thus for developing more valid therapeutic strategies.