TG and thyroid gland disorder: For example, effects on the circulatory system or metabolic pathways. Due to these close relations with the nervous system function, disturbances of thyroid function with low levels of thyroid hormones are associated with a wide spectrum of neurological signs and symptoms, including mood and cognitive disorders, headache, tremors, muscle weakness, movement disorders, sluggish reflexes, and inattentiveness, etc. [8].