|Nielsen, Forrest - Frosty|
Submitted to: Journal of Nutrition Health and Aging
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/26/2006
Publication Date: 1/30/2008
Citation: Lam, P.K., Kritz-Silverstein, D., Barrett-Connor, E., Nielsen, F.H., Milne, D., Gamst, A., Morton, D., Wingard, D. 2008. Plasma trace elements and cognitive function in older men and women: The Rancho Bernardo Study. Journal of Nutrition Health and Aging. 12(1):22-27. Interpretive Summary: It has been estimated that the prevalence of mild cognitive (brain) function impairment among older adults exceeds 20%. This age-related cognitive impairment may be caused in part by poor nutritional status, including poor iron, zinc and/or copper status. Thus, a study was performed to determine whether plasma iron, zinc and copper concentrations were associated with brain function (assessed by using 12 standardized cognitive function tests) in older people, and whether any association was affected by sex. Participants in this study were community-dwelling adults (849 women and 602 men) with the mean age of 75 years. In the sex-specific analyses, adjustments were made for age, education, alcohol consumption, smoking, exercise and estrogen use (women). For women, high plasma iron and copper concentrations were associated with poorer performance on four memory tests, while low plasma zinc concentrations were associated with poorer performance in a test of concentration. For men, both low and high plasma iron and copper concentrations were associated with poorer performance on four tests of recall and concentration; plasma zinc concentrations were not associated with any test performance. These findings suggest that sub-optimal nutritional status resulting in low, and sometimes high circulating concentrations of iron, zinc and copper can detrimentally affect cognitive function in older adults and that the effects may differ by sex.
Technical Abstract: Results from studies of trace elements and brain function are inconsistent. This study examines whether plasma iron, copper, or zinc levels are associated with cognitive function and whether observed associations differ by sex. Participants were community-dwelling adults (849 women, 602 men) with mean age of 75 years. During a cohort examination between 1988-1992, 12 standardized cognitive-function tests were administered by trained interviewers, and blood samples were obtained for analysis of iron, copper, and zinc using an inductively coupled plasma atomic emission spectrometer. Sex-specific analyses were performed, adjusting for age, education, alcohol consumption, smoking, exercise, and estrogen use (women). For women, higher iron and copper levels were associated with poorer performance on four memory tests (negative-linear effects, p's(less than or equal to)0.05), while lower zinc levels were associated with poorer performance on a single test of concentration (positive-linear effect, p=0.008). For men, both lower and higher iron and copper levels were associated with poorer performance on four tests of recall and concentration than intermediate levels (quadratic effects, p's(less than or equal to)0.04), while zinc was not related to any test performance. These cross-sectional findings suggest that optimal trace minerals levels may exist for optimal cognitive function in older adults and raise the possibility that these levels differ by sex.