Assessment of the effects of glutamic acid decarboxylase antibodies and trace elements on cognitive performance in older adults

BACKGROUND Homeostatic imbalance of trace elements such as iron (Fe), copper (Cu), and zinc (Zn) demonstrated adverse effects on brain function among older adults. OBJECTIVE The present study aimed to investigate the effects of trace elements and the presence of anti-glutamic acid decarboxylase antibodies (GADAs) in human cognitive abilities among healthy older adults. METHODS A total of 100 healthy subjects (65 males, 35 females; age range; 64-96 years) were recruited for this study. Based on Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) score, the participants were classified according to cognitive performance into normal (n=45), moderate (n=30), and severe (n=25). Cognitive functioning, leisure-time physical activity (LTPA), serum trace elements - Fe, Cu, Zn, Zn/Cu, and GADAs were assessed using LOTCA battery, pre-validated physical activity (PA) questionnaire, atomic absorption, and immunoassay techniques, respectively. RESULTS Approximately 45% of the study population (n=45) had normal distribution of cognitive function and 55% of the study population (n=55) had abnormal cognitive function; they were classified into moderate (score 62-92) and severe (score 31-62). There was a significant reduction in the level of Zn and Zn/Cu ratio along with an increase in the level of Fe, Cu, and anti-GADAs in subjects of severe (P=0.01) and moderate (P=0.01) cognitive performance. LOTCA-cognitive scores correlated positively with sex, HbA(1c), Fe, Cu, Zn, and Zn/Cu ratio, and negatively with age, PA, body mass index, and anti-GADAs. Significant inter-correlation was reported between serum trace element concentrations and anti-GADAs which suggest producing a cognitive decline via oxidative and neural damage mechanism. CONCLUSION This study found significant associations among trace elements, anti-GADAs, and cognitive function in older adults. The homeostatic balance of trace elements should be recommended among older adults for better cognitive performance.