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Omega-6 to omega-3 fatty acid ratio and higher-order cognitive functions in 7- to 9-y-olds: a cross-sectional study.
Sheppard, KW, Cheatham, CL
The American journal of clinical nutrition. 2013;(3):659-67
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Abstract
BACKGROUND Biochemical and behavioral evidence has suggested that the ratio of n-6 (omega-6) to n-3 (omega-3) could be an important predictor of executive function abilities in children. OBJECTIVE We determined the relation between the ratio of n-6 to n-3 and cognitive function in children. We hypothesized that children with lower ratios of n-6 to n-3 fatty acids would perform better on tests of planning and working memory. DESIGN Seventy 7- to 9-y-old children completed three 24-h diet recalls and a subset of the Cambridge Neuropsychological Test Assessment Battery. Parents provided information on their demographics and children's diet histories. RESULTS Mean n-3 and mean n-6 intakes were related to the mean time spent on each action taken in the planning problem. The ratio of n-6 to n-3 significantly predicted performance on the working memory and planning problems. There was a significant interaction between the ratio and fatty acid intake; when children had high ratios, a higher intake of n-3 fatty acids predicted a better performance on the planning task than when children had lower n-3 intakes. When children had low ratios, a lower intake of n-3 and lower intake of n-6 predicted better performance than when intakes were higher. CONCLUSIONS The relation between cognitive abilities and the ratio of n-6 to n-3 may be mediated by an enzymatic affinity for n-3 fatty acids. The ratio of n-6 to n-3 should be considered an important factor in the study of fatty acids and cognitive development. This trial was registered at clinicaltrials.gov as NCT01823419.
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Practice effects in a longitudinal, multi-center Alzheimer's disease prevention clinical trial.
Abner, EL, Dennis, BC, Mathews, MJ, Mendiondo, MS, Caban-Holt, A, Kryscio, RJ, Schmitt, FA, , , Crowley, JJ, ,
Trials. 2012;:217
Abstract
BACKGROUND Practice effects are a known threat to reliability and validity in clinical trials. Few studies have investigated the potential influence of practice on repeated screening measures in longitudinal clinical trials with a focus on dementia prevention. The current study investigates whether practice effects exist on a screening measure commonly used in aging research, the Memory Impairment Screen (MIS). METHODS The PREADViSE trial is a clinical intervention study evaluating the efficacy of vitamin E and selenium for Alzheimer's disease prevention. Participants are screened annually for incident dementia with the MIS. Participants with baseline and three consecutive follow-ups who made less than a perfect score at one or more assessments were included in the current analyses (N=1,803). An additional subset of participants with four consecutive assessments but who received the same version of the MIS at baseline and first follow-up (N=301) was also assessed to determine the effects of alternate forms on mitigating practice. We hypothesized that despite efforts to mitigate practice effects with alternate versions, MIS scores would improve with repeated screening. Linear mixed models were used to estimate mean MIS scores over time. RESULTS Among men with four visits and alternating MIS versions, although there is little evidence of a significant practice effect at the first follow-up, mean scores clearly improve at the second and third follow-ups for all but the oldest participants. Unlike those who received alternate versions, men given the same version at first follow-up show significant practice effects. CONCLUSION While increases in the overall means were small, they represent a significant number of men whose scores improved with repeated testing. Such improvements could bias case ascertainment if not taken into account.
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Oral creatine monohydrate supplementation improves brain performance: a double-blind, placebo-controlled, cross-over trial.
Rae, C, Digney, AL, McEwan, SR, Bates, TC
Proceedings. Biological sciences. 2003;(1529):2147-50
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Abstract
Creatine supplementation is in widespread use to enhance sports-fitness performance, and has been trialled successfully in the treatment of neurological, neuromuscular and atherosclerotic disease. Creatine plays a pivotal role in brain energy homeostasis, being a temporal and spatial buffer for cytosolic and mitochondrial pools of the cellular energy currency, adenosine triphosphate and its regulator, adenosine diphosphate. In this work, we tested the hypothesis that oral creatine supplementation (5 g d(-1) for six weeks) would enhance intelligence test scores and working memory performance in 45 young adult, vegetarian subjects in a double-blind, placebo-controlled, cross-over design. Creatine supplementation had a significant positive effect (p < 0.0001) on both working memory (backward digit span) and intelligence (Raven's Advanced Progressive Matrices), both tasks that require speed of processing. These findings underline a dynamic and significant role of brain energy capacity in influencing brain performance.
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Involvement of human amygdala and orbitofrontal cortex in hunger-enhanced memory for food stimuli.
Morris, JS, Dolan, RJ
The Journal of neuroscience : the official journal of the Society for Neuroscience. 2001;(14):5304-10
Abstract
We used positron emission tomography to measure regional cerebral blood flow (rCBF) in 10 healthy volunteers performing a recognition memory task with food and non-food items. The biological salience of the food stimuli was manipulated by requiring subjects to fast before the experiment and eat to satiation at fixed time points during scanning. All subjects showed enhanced recognition of food stimuli (relative to non-food) in the fasting state. Satiation significantly reduced the memory advantage for food. Left amygdala rCBF covaried positively with recognition memory for food items, whereas rCBF in right anterior orbitofrontal cortex covaried with overall memory performance. Right posterior orbitofrontal rCBF covaried positively with hunger ratings during presentation of food items. Regression analysis of the neuroimaging data revealed that left amygdala and right lateral orbitofrontal rCBF covaried as a function of stimulus category (i.e., food vs non-food). These results indicate the involvement of amygdala and discrete regions of orbitofrontal cortex in the integration of perceptual (food), motivational (hunger), and cognitive (memory) processes in the human brain.