Selenium and cognition: Mechanism and evidence

Abstract

Selenium (Se) is important for cognition by way of its contribution to the reduction of oxidative stress. Reactive species (RS) are generated during the normal course of metabolism in the body. Evidence shows that RS are known to regulate cellular functions. They also participate in the immune system and biosynthesis of macromolecules. On the other hand, accumulated RS are highly toxic to the body and they are major concern in the pathogenesis of chronic diseases including cancers, cardiovascular disease, and neurodegenerative diseases. Every aerobic cell is vulnerable to attack by RS consequently, resulting in oxidative stress. However, the brain is particularly susceptible to oxidative stress due to its composition and physiology. Oxidative stress to the brain is associated with cognitive deficits, mood disorders, and behavioral problems. Evidence from animal and human studies suggest the importance of selenium for cognitive performance, mood, and behavior through protection against oxidative damage to substrates including low-density lipoproteins (LDL), hydroperoxide, hydrogen peroxide, peroxynitrite, and tert-butyl hydroxyperoxide (t-BHP). The dose response relationship between Se and cognitive performance is nonlinear suggesting both deficiency and excess intake results in adverse neurobehavioral outcomes. In addition, through its role in thyroid metabolism, limited evidence suggests the importance of selenium in improving cognitive performance of persons with hypothyroidism.