Affiliations: Department of Neurosciences Psychiatric and Anesthesiological Sciences, University of Messina, Policlinico Universitario “G.Martino”, Via Consolare Valeria, 98125 Messina, Italy
Correspondence:
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Corresponding author: Vincenzo Fodale, MD, Department of Neurosciences, Psychiatric and Anesthesiological Sciences, Policlinico Universitario, via C.Valeria, 98125 Messina, Italy. Tel. (Hospital):
+39 090 2212814; (Cell): +39 340 4826 330; Fax: +39 090 221 2821; E-mail: vfodale@unime.it.
Abstract: Hypothyroidism and hyperthyroidism are commonly present conditions in adults, leading to neurological symptoms, affecting the central and peripheral nervous system, and to neurocognitive impairment. Several studies investigated a possible association between Alzheimer's disease (AD) and thyroid dysfunctions. Increasing evidence supports an extensive interrelationship between thyroid hormones and the cholinergic system, which is selectively and early affected in AD. Moreover, thyroid hormones negatively regulate expression of the amyloid-β protein precursor (AβPP), which plays a key role in the development of AD. A condition, the so called euthyroid sick syndrome (ESS), characterized by reduced serum T3 and T4 concentrations without increased serum thyroid stimulation hormone secretion, occurs within hours after major surgery. After surgery, elderly patients often exhibit a transient, reversible state of cognitive alterations. Delirium occurs in 10–26% of general medical patients over 65, and it is associated with a significant increase in morbidity and mortality. Modifications in thyroid hormone functioning may take place as a consequence of psycho-physical stress caused by surgery, and probably as a consequence of reduced conversion of T4 into T3 by the liver engaged in metabolizing anesthetic drugs. Therefore, modifications of thyroid hormones post-surgery, might play a role in the pathogenesis of postoperative cognitive dysfunction.
