***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Dietary intake of fish and the omega-3 fatty acids have been associated with lower risk of Alzheimer disease and stroke . OBJECTIVE To examine whether intakes of fish and the omega-3 fatty acids protect against  age-related cognitive decline .  DESIGN Prospect i ve cohort study . SETTING Geographically defined Chicago , Ill , community . PARTICIPANTS Residents , 65 years and older , who participated in the Chicago Health and Aging Project . MAIN OUTCOME MEASURE Change in a global cognitive score estimated from mixed models . The global score was computed by summing scores of 4 st and ardized tests . In-home cognitive assessment  s were performed 3 times over 6 years of follow-up . RESULTS Cognitive scores declined on average at a rate of 0.04 st and ardized units per year ( SU/y ) . Fish intake was associated with a slower rate of cognitive decline in mixed models adjusted for age , sex , race , education , cognitive activity , physical activity , alcohol consumption , and total energy intake . Compared with a decline rate in score of -0.100 SU/y among persons who consumed fish less than weekly , the rate was 10 % slower ( -0.090 SU/y ) among persons who consumed 1 fish meal per week and 13 % slower ( -0.088 SU/y ) among persons who consumed 2 or more fish meals per week . The fish association was not accounted for by cardiovascular-related conditions or fruit and vegetable consumption but was modified after adjustment for intakes of saturated , polyunsaturated , and trans fats . There was little evidence that the omega-3 polyunsaturated fatty acids were associated with cognitive change . CONCLUSIONS Fish consumption may be associated with slower cognitive decline with age . Further study is needed to determine whether fat composition is the relevant dietary constituent In a test of the effects of cortisol on emotional memory , 90 men were orally administered  placebo or 20 or 40 mg cortisol and presented with emotionally arousing and neutral stimuli . On memory tests administered within 1 hr of stimulus presentation , cortisol elevations caused a reduction in the number of errors committed on free-recall tasks . Two evenings later , when cortisol levels were no longer manipulated , inverted-U quadratic trends were found for recognition memory tasks , reflecting memory facilitation in the 20-mg group for both negative and neutral information . Results suggest that the effects of cortisol on memory do not differ substantially for emotional and neutral information . The study provides evidence of beneficial effects of acute cortisol elevations on explicit memory in humans BACKGROUND Adherence to a Mediterranean diet may improve longevity , but relevant data are limited . METHODS We conducted a population -based , prospect i ve investigation involving 22,043 adults in Greece who completed an extensive , vali date d , food-frequency question naire at base line .  Adherence to the traditional Mediterranean diet was assessed by a 10-point Mediterranean-diet scale that incorporated the salient characteristics of this diet ( range of scores , 0 to 9 , with higher scores indicating greater adherence ) . We used proportional-hazards regression to assess the relation between adherence to the Mediterranean diet and total mortality , as well as mortality due to coronary heart disease and mortality due to cancer , with adjustment for age , sex , body-mass index , physical-activity level , and other potential confounders . RESULTS During a median of 44 months of follow-up , there were 275 deaths . A higher degree of adherence to the Mediterranean diet was associated with a reduction in total mortality ( adjusted hazard ratio for death associated with a two-point increment in the Mediterranean-diet score , 0.75 [ 95 percent confidence interval , 0.64 to 0.87 ] ) . An inverse association with greater adherence to this diet was evident for both death due to coronary heart disease ( adjusted hazard ratio , 0.67 [ 95 percent confidence interval , 0.47 to 0.94 ] ) and death due to cancer ( adjusted hazard ratio , 0.76 [ 95 percent confidence interval , 0.59 to 0.98 ] ) . Associations between individual food groups contributing to the Mediterranean-diet score and total mortality were generally not significant . CONCLUSIONS Greater adherence to the traditional Mediterranean diet is associated with a significant reduction in total mortality BACKGROUND While high adiposity in middle age appears to be related to greater dementia risk , studies exploring this association in the elderly are conflicting . OBJECTIVE To evaluate associations between midlife and late-life obesity and risk of dementia . DESIGN Prospect i ve study with mean follow-up of 5.4 years ( 1992 - 1994 through 1999 ) . SETTING Community-dwelling sample in 4 US sites recruited from Medicare eligibility files . PARTICIPANTS A total of 2798 adults without dementia ( mean age , 74.7 years ; 59.1 % women ) participating in the Cardiovascular Health Study who underwent magnetic resonance imaging were measured for height and weight at baseline at age 65 years or older ( late life ) , and self-reported weight at age 50 years ( midlife ) . Body mass index ( BMI ) ( calculated as weight in kilograms divided by height in meters squared ) was calculated at both times . MAIN OUTCOME MEASURES Dementia , Alzheimer disease , and vascular dementia classified by a multidisciplinary committee using st and ardized criteria . RESULTS Classification result ed in 480 persons with incident dementia , 245 with Alzheimer disease ( no vascular dementia ) , and 213 with vascular dementia ( with or without Alzheimer disease ) . In evaluations of midlife obesity , an increased risk of dementia was found for obese ( BMI > 30 ) vs normal-weight ( BMI 20 - 25 ) persons , adjusted for demographics ( hazard ratio [ HR ] , 1.39 ; 95 % confidence interval [ CI ] , 1.03 - 1.87 ) and for cardiovascular risk factors ( 1.36 ; 0.94 - 1.95 ) . The risk estimates were reversed in assessment s of late-life BMI . Underweight persons ( BMI < 20 ) had an increased risk of dementia ( 1.62 ; 1.02 - 2.64 ) , whereas being overweight ( BMI > 25 - 30 ) was not associated ( 0.92 ; 0.72 - 1.18 ) and being obese reduced the risk of dementia ( 0.63 ; 0.44 - 0.91 ) compared with those with normal BMI . CONCLUSION These results help explain the " obesity paradox " as differences in dementia risk across time are consistent with physical changes in the trajectory toward disability The current study used a r and omized , double-blind , placebo-controlled design to investigate the effects of saccharide supplementation on cognition and well-being in middle-aged adults . Participants ( N = 109 ; 45–60 years ) took a teaspoon of a combination of saccharides or a placebo twice daily for 12 weeks ( 3.6 g per day ) . Before and after this supplementation period , participants completed alternate forms of st and ardized tests of cognition and self-report measures of well-being . Significant beneficial effects of saccharide supplementation were found for memory performance and indicators of well-being . The potential for these nutrients to optimize cognitive function and well-being in older adults warrants ongoing investigation BACKGROUND Cognitive performance often declines under chronic stress exposure . The negative effect of chronic stress on performance may be mediated by reduced brain serotonin function . The uptake of the serotonin precursor tryptophan into the brain depends on nutrients that influence the availability of tryptophan by changing the ratio of plasma tryptophan to the sum of the other large neutral amino acids ( Trp-LNAA ratio ) . In addition , a diet-induced increase in tryptophan may increase brain serotonergic activity levels and improve cognitive performance , particularly in high stress-vulnerable subjects . OBJECTIVE We tested whether alpha-lactalbumin , a whey protein with a high tryptophan content , would increase the plasma Trp-LNAA ratio and improve cognitive performance in high stress- vulnerable subjects . DESIGN Twenty-three high stress-vulnerable subjects and 29 low stress-vulnerable subjects participated in a double-blind , placebo-controlled , crossover study . All subjects conducted a  memory-scanning task after the intake of a diet enriched with either alpha-lactalbumin ( alpha-lactalbumin diet ) or sodium caseinate ( control diet ) . Blood sample s were taken to measure the effect of dietary manipulation on the plasma Trp-LNAA ratio . RESULTS A significantly greater increase in the plasma Trp-LNAA ratio after consumption of the alpha-lactalbumin diet than after the control diet ( P = 0.0001 ) was observed ; memory scanning improved significantly only in the high stress-vulnerable subjects ( P = 0.019 ) . CONCLUSION Because an increase in the plasma Trp-LNAA ratio is considered to be an indirect indication of increased brain serotonin function , the results suggest that dietary protein rich in alpha-lactalbumin improves cognitive performance in stress-vulnerable subjects via increased brain tryptophan and serotonin activities BACKGROUND Dietary carbohydrates can improve memory . Whether these effects are related to elevations in blood glucose or to energy ingestion is unknown . OBJECTIVES Our objectives were to determine 1 ) the influence of isoenergetic protein- , carbohydrate- , and fat-containing drinks on cognitive performance and 2 ) whether the time period after ingestion affects cognition . DESIGN After fasting overnight , 11 men and 11 women aged 61 - 79 y consumed either a 300-mL drink containing 774 kJ as pure protein ( whey ) , carbohydrate ( glucose ) , or fat ( safflower oil ) or a nonenergy placebo on 4 separate mornings .  Cognitive tests were administered 15 and 60 min after ingestion of the drinks . Plasma glucose and serum insulin concentrations were measured . RESULTS Only the carbohydrate drink increased blood glucose ( P < 0.0001 ) . Compared with the placebo , all 3 macronutrients improved delayed paragraph recall ( PR ) ( P < 0.001 ) and improved or tended to improve immediate PR ( P < 0.04 ) 15 min after ingestion . Beneficial effects on other cognitive tests were confined to one or more of the macronutrients : carbohydrate improved Trail Making Test ( Trails ) performance at 60 min ( P = 0.02 ) and tended to improve Trails at 15 min ( P = 0.04 ) and PR at 60 min in men , carbohydrate and fat improved or tended to improve performance on Trails at 15 and 60 min in subjects with poor baseline scores ( r > -0.41 , P < 0.03 ) , fat tended to improve attention at 60 min ( P < 0.05 ) , and protein reduced the rate of forgetting on the PR at 15 min ( P = 0.002 ) . CONCLUSIONS Energy intake from protein , carbohydrate , or fat can enhance memory independently of elevations in blood glucose . Each macronutrient may also exert unique effects on cognition BACKGROUND A glucose drink has been shown to improve memory in persons with poor glucose regulation and poor cognition . OBJECTIVE The objective of this study was to determine 1 ) whether an association between cognition and glucose regulation is apparent in healthy seniors and 2 ) the effects of dietary carbohydrates on cognition . DESIGN After an overnight fast , 10 men and 10 women ( aged 60 - 82 y ) consumed 50 g carbohydrate as glucose , potatoes , or barley or a placebo on 4 separate mornings . Cognitive tests were administered 15 , 60 , and 105 min after ingestion of the carbohydrate .  Plasma glucose and serum insulin were measured . RESULTS In a multiple regression analysis , poor baseline ( placebo )  verbal declarative memory ( immediate and 20-min delayed paragraph recall and word list recall ) and visuomotor task performance were predicted by poor beta cell function , high incremental area under the glucose curve , low insulin resistance , and low body mass index . The difference in plasma glucose after food consumption [ glucose > potatoes > barley > placebo ( P : < 0.03 ) ] did not predict performance . Although overall performance did not differ with consumption of the different test foods , baseline score and beta cell function correlated with improvements in immediate and delayed paragraph recall for all 3 carbohydrates ( compared with placebo ) ; the poorer the baseline memory or beta cell function , the greater the improvement ( correlation between beta cell function and improvement in delayed paragraph recall : r > -0.50 , P : < 0.03 ) . Poor beta cell function correlated with improvement for all carbohydrates in visuomotor task performance but not on an attention task . CONCLUSIONS Glucose regulation was associated with cognitive performance in elderly subjects with normal glucose tolerance . Dietary carbohydrates ( potatoes and barley ) enhanced cognition in subjects with poor memories or beta cell function independently of plasma glucose BACKGROUND Low-carbohydrate diets are often used to promote weight loss , but their effects on psychological function are largely unknown . OBJECT 
    Output:
    
MAIN RESULTS There is no suitable RCT of any form of carbohydrates involving  independent-living older adults with normal cognition or mild cognitive impairment .
AUTHORS ' CONCLUSIONS There are no suitable RCTs on which to base any recommendations about the use of any form of carbohydrate for enhancing cognitive performance in older adults with normal cognition or mild cognitive impairment .