The research team observed that replacing the selenium content in GPX4 with sulfur did not improve the animal models' life span. According to the scientists, mouse models with sulfur-based GPX4 enzyme did not survive for more than three weeks. The animals' shorter lifespan was largely due in part to neurological complications, the researchers explained. The experts also observed that a distinct subpopulation of specialized brain neurons were lost during the postnatal development when selenium-containing GPX4 was not present.
"Our study demonstrates for the first time that selenium is an essential factor for the postnatal development of a specific type of interneurons. Selenium-containing GPX4 protects these specialized neurons from oxidative stress and from ferroptotic cell death," researcher Dr. José Pedro Friedmann Angeli said in a press release.
Studies: Selenium also mitigates depression, brain loss
Previous studies have also demonstrated that selenium helps improve brain health and effectively stave off related conditions. For instance, a 2014 study published in the Journal of Nutrition revealed that adequate selenium levels may prevent the onset of depressive symptoms and negative mood. The study was carried out by researchers at the University of Otago in New Zealand.
The research team pooled data on 978 young adults aged 17 to 25 years old as part of the study. The volunteers were instructed to accomplish a depression questionnaire and monitor their mood daily for two weeks. The participants' selenium levels were determined through a series of blood tests. The health experts found that volunteers who had extremely low selenium levels were at an increased risk of depressive symptoms and poorer mood. However, the research team noted that adequate selenium intake may mitigate the risk of depression.
"Our strongest finding was that young adults with the lowest selenium concentrations reported the most depressive symptoms. Although we did not test the physiological mechanisms, other research shows that oxidative damage to the brain and nervous system contributes to the development of depression. Adequate selenium intake is required for optimal antioxidant defenses to protect body tissues from oxidative damage, through glutathione peroxidise, which is a key antioxidant enzyme," study leader Dr. Tamlin Conner told Medical Xpress online.
Another study published in the American Journal of Epidemiology showed that selenium intake may reduce the odds of brain loss associated with aging. Health experts conducted a cross-sectional survey of cognitive function in rural elderly Chinese as part of the research. The scientists have examined the volunteers' nail samples in order to determine their selenium levels. (Related: Selenium intake prevents loss of brain function as we age.)
The research team observed a stark difference in cognitive scores between participants with the lowest selenium levels and those with the highest selenium levels. According to the scientists, the score discrepancy was equivalent to a 10-year age difference between the groups. The results underscore the importance of long-term selenium intake given that the brain has a different reaction to the compound compared with the rest of the body. The experts also stressed on the importance of prolonged selenium intake as the slowest-maturing brain regions are usually the primary target of Alzheimer's disease.
"In our population, selenium had a consistent, dose-response relation with cognitive performance, such that higher selenium levels were associated with better cognition...New learning measures, such as the CERAD Word List Learning Test task and the IU Story Recall Test, were also clearly related to selenium levels," the researchers wrote.
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