***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 n-3 polyunsaturated fatty acids improve brain functioning in animal studies , but there is limited study of whether this type of fat protects against Alzheimer disease . OBJECTIVE To examine whether fish consumption and intake of different types of n-3 fatty acids protect against Alzheimer disease . DESIGN Prospect i ve study conducted from 1993 through 2000 , of a stratified r and om sample from a geographically defined community . Participants were followed up for an average of 3.9 years for the development of Alzheimer disease . PATIENTS A total of 815 residents , aged 65 to 94 years , who were initially unaffected by Alzheimer disease and completed a dietary question naire on average 2.3 years before clinical evaluation of incident disease . MAIN OUTCOME MEASURES Incident Alzheimer disease diagnosed in a structured neurologic examination by means of st and ardized criteria . RESULTS A total of 131 sample participants developed Alzheimer disease . Participants who consumed fish once per week or more had 60 % less risk of Alzheimer disease compared with those who rarely or never ate fish ( relative risk , 0.4 ; 95 % confidence interval , 0.2 - 0.9 ) in a model adjusted for age and other risk factors . Total intake of n-3 polyunsaturated fatty acids was associated with reduced risk of Alzheimer disease , as was intake of docosahexaenoic acid ( 22:6n-3 ) . Eicosapentaenoic acid ( 20:5n-3 ) was not associated with Alzheimer disease . The associations remained unchanged with additional adjustment for intakes of other dietary fats and of vitamin E and for cardiovascular conditions . CONCLUSION Dietary intake of n-3 fatty acids and weekly consumption of fish may reduce the risk of incident Alzheimer disease BACKGROUND Emerging evidence suggests that docosahexaenoic acid ( DHA , 22:6n-3 ) , the principal omega-3 ( n-3 ) fatty acid in brain gray matter , positively regulates cortical metabolic function and cognitive development . However , the effects of DHA supplementation on functional cortical activity in human subjects are unknown . OBJECTIVE The objective was to determine the effects of DHA supplementation on functional cortical activity during sustained attention in human subjects . DESIGN Healthy boys aged 8 - 10 y ( n = 33 ) were r and omly assigned to receive placebo or 1 of 2 doses of DHA ( 400 or 1200 mg/d ) for 8 wk . Relative changes in cortical activation patterns during sustained attention at baseline and endpoint were determined by functional magnetic resonance imaging . RESULTS At 8 wk , erythrocyte membrane DHA composition increased significantly from baseline in subjects who received low-dose ( by 47 % ) or high-dose ( by 70 % ) DHA but not in those who received placebo ( -11 % ) . During sustained attention , both DHA dose groups had significantly greater changes from baseline in activation of the dorsolateral prefrontal cortex than did the placebo group , and the low-dose and high-dose DHA groups had greater decreases in the occipital cortex and cerebellar cortex , respectively . Relative to low-dose DHA , high-dose DHA result ed in greater decreases in activation of bilateral cerebellum . The erythrocyte DHA composition was positively correlated with dorsolateral prefrontal cortex activation and was inversely correlated with reaction time , at baseline and endpoint . CONCLUSION Dietary DHA intake and associated elevations in erythrocyte DHA composition are associated with alterations in functional activity in cortical attention networks during sustained attention in healthy boys . This trial was registered at clinical trials.gov as NCT00662142 Background : Dietary fish oils , rich in long-chain n-3 ( ω-3 ) fatty acids ( FAs ) [ e.g. , docosahexaenoic acid ( DHA , 22:6n-3 ) and eicosapentaenoic acid ( EPA , 20:5n-3 ) ] , modulate inflammatory reactions through various mechanisms , including gene expression , which is measured as messenger RNA concentration . However , the effects of long-term treatment of humans with DHA and EPA on various epigenetic factors-such as DNA methylation , which controls messenger RNA generation-are poorly described . Objective : We wanted to determine the effects of 6 mo of dietary supplementation with an n-3 FA preparation rich in DHA on global DNA methylation of peripheral blood leukocytes ( PBLs ) and the relation to plasma EPA and DHA concentrations in Alzheimer disease ( AD ) patients . Design : In the present study , DNA methylation in four 5'-cytosine-phosphate-guanine-3 ' ( CpG ) sites of long interspersed nuclear element-1 repetitive sequences was assessed in a group of 63 patients ( 30 given the n-3 FA preparation and 33 given placebo )  as an estimation of the global DNA methylation in blood cells . Patients originated from the r and omized , double-blind , placebo-controlled OmegAD study , in which 174 AD patients received either 1.7 g DHA and 0.6 g EPA ( the n-3 FA group ) or placebo daily for 6 mo . Results : At 6 mo , the n-3 FA group displayed marked increases in DHA and EPA plasma concentrations ( 2.6- and 3.5-fold ) , as well as decreased methylation in 2 out of 4 CpG sites ( P < 0.05 for all ) , respectively . This hypomethylation in CpG2 and CpG4 sites showed a reverse correlation to changes in plasma EPA concentration ( r = -0.25 , P = 0.045 ; and r = -0.26 , P = 0.041 , respectively ) , but not to changes in plasma DHA concentration , and were not related to apolipoprotein E-4 allele frequency . Conclusion : Supplementation with n-3 FA for 6 mo was associated with global DNA hypomethylation in PBLs . Our data may be of importance in measuring various effects of marine oils , including gene expression , in patients with AD and in other patients taking n-3 FA supplements  . This trial was registered at clinical trials.gov as NCT00211159 Given evidence that eicosapentaenoic acid ( EPA ) , docosahexaenoic acid ( DHA ) , and anthocyanin-rich blueberries provide neurocognitive benefit , we investigated long-term supplementation in older adults with cognitive complaints .  In a 24-week r and omized , double-blind , placebo-controlled trial , elderly men and women received daily fish oil ( FO ) or blueberry ( BB ) or both . Diet records confirmed that participants reduced background consumption of EPA , DHA , and anthocyanins as prescribed . Erythrocyte EPA + DHA composition increased in the FO groups ( p = 0.0001 ) . Total urinary anthocyanins did not differ between the groups after supplementation but glycoside and native ( food ) forms increased only in the BB-supplemented groups . The FO ( p = 0.03 ) and BB ( p = 0.05 ) groups reported fewer cognitive symptoms , and the BB group showed improved memory discrimination ( p = 0.04 ) , indicating that supplementation improved cognition . Cognitive benefit in the BB group was associated with the presence of urinary anthocyanins reflecting recent BB intake but not with anthocyanin metabolites . However , combined FO + BB treatment was not associated with cognitive enhancement as expected BACKGROUND Subjects with a mild cognitive impairment ( MCI ) have a memory impairment beyond that expected for age and education yet are not demented . These subjects are becoming the focus of many prediction studies and early intervention trials . OBJECTIVE To characterize clinical ly subjects with MCI  cross-sectionally and longitudinally . DESIGN A prospect i ve , longitudinal inception cohort . SETTING General community clinic . PARTICIPANTS A sample of 76 consecutively evaluated subjects with MCI were compared with 234 healthy control subjects and 106 patients with mild Alzheimer disease ( AD ) , all from a community setting as part of the Mayo Clinic Alzheimer 's Disease Center/Alzheimer 's Disease Patient Registry , Rochester , Minn. MAIN OUTCOME MEASURES The 3 groups of individuals were compared on demographic factors and measures of cognitive function including the  Mini-Mental State Examination , Wechsler Adult Intelligence Scale-Revised , Wechsler Memory Scale-Revised , Dementia Rating Scale , Free and Cued Selective Reminding Test , and Auditory Verbal Learning Test .  Clinical classifications of dementia and AD were determined according to the Diagnostic and Statistical Manual of Mental Disorders , Revised Third Edition and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer 's Disease and Related Disorders Association criteria , respectively . RESULTS The primary distinction between control subjects and subjects with MCI was in the area of memory , while other cognitive functions were comparable . However , when the subjects with MCI were compared with the patients with very mild AD , memory performance was similar , but patients with AD were more impaired in other cognitive domains as well . Longitudinal performance demonstrated that the subjects with MCI declined at a rate greater than that of the controls but less rapidly than the patients with mild AD . CONCLUSIONS Patients who meet the criteria for MCI can be differentiated from healthy control subjects and those with very mild AD . They appear to constitute a clinical entity that can be characterized for treatment interventions Background / objectives to investigate the effects of a 3-year multidomain lifestyle intervention , omega-3 supplementation or both on  physical activity  ( PA ) in older adults with subjective memory complaints . Design / setting s/subjects the Multidomain Alzheimer Preventive Trial was a 3-year r and omised controlled trial that enroled 1,680 community-dwelling adults aged 70 years or over , with subjective memory complaints . Participants were r and omised to omega-3 supplementation ( total daily dose of 800 mg docosahexanoic acid and up to 225 mg eicosapentanoic acid ) , multidomain intervention ( nutritional and exercise counselling and cognitive training ) , omega-3 plus multidomain intervention or placebo with usual care . Methods PA was assessed using a self-reported question naire . From this , global moderate-to-vigorous PA , leisure-time PA , non-leisure-time PA and light PA were measured in metabolic equivalent tasks-minutes per week ( MET-min/week ) . Results in the multidomain groups , participants significantly increased their moderate-to-vigorous and leisure-time PA at 6 months ( ≥300 MET-min/week for both in the multidomain groups ; P ≤ 0.002 ) before returning to baseline by the end of the trial . Activity in the placebo/usual care and omega-3/usual care groups declined overtime . Between-group differences remained significant for both multidomain groups for leisure-time physical activity at 2- and 3-year follow-ups . Compared to placebo/usual care , interventions had no significant effects on non-leisure-time PA and light PA . Omega-3 supplementation alone had no effects on PA . Conclusions a multidomain intervention focused on cognitive training , and nutritional and PA counselling increased PA in the short-term and limited its decline in the long-term among older adults with memory complaints . Clinical Trials.gov- Registration number : NCT0067268 Background Cognitive decline has been reported following cardiac surgery , leading to great interest in interventions to minimize its occurrence . Long-chain n-3 ( ω-3 ) polyunsaturated fatty acids ( PUFAs ) have been associated with less cognitive decline in observational studies , yet no trials have tested the effects of n-3 PUFAs on cognitive decline after surgery . Objective We sought to determine whether perioperative n-3 PUFA supplementation reduces postoperative cognitive decline in patients postcardiac surgery . Methods The study comprised a r and omized , double-blind , placebo-controlled , multicenter , clinical trial conducted on cardiac surgery recipients at 9 tertiary care medical centers across the United States . Patients were r and omly assigned to receive fish oil ( 1-g capsules containing ≥840 mg n-3 PUFAs as ethyl esters ) or placebo , with preoperative loading of 8 - 10 g over 2 - 5 d followed postoperatively by 2 g/d until hospital discharge or postoperative day 10 , whichever came first . Global cognition was assessed using in-person testing over 30 d with the Repeatable Battery for the Assessment of Neuropsychological Status ( RBANS ) ( primary outcome ) , Mini-Mental State Exam ( secondary outcome ) , and Trails A and B ( secondary outcome ) tests . All end points were prespecified . Statistical methods were employed , including descriptive statistics , logistic regression , and various sensitivity analyses . Results A total of 320 US patients were enrolled in the Omega-3 Fatty Acids for Prevention of Post-Operative Atrial Fibrillation ( OPERA ) Cognitive Trial ( OCT ) , a sub study of OPERA . The median age was 62 y ( IQR 53 , 70 y ) . No differences in global cognition were observed between placebo and fish oil groups at day 30 ( P = 0.32 ) for the primary outcome , a composite neuropsychological RBANS score . The population demonstrated resolution of initial 4-d cognitive decline back to baseline function by 30 d on the RBANS . Con 
    Output:
    
Docosahexaenoic ( DHA ) and vaccenic acids  were significantly lower and higher respectively in MCI relative to controls .
Total fatty acids were 27.2 % lower in AD relative to controls , and this was reflected almost uniformly in all specific fatty acids in AD .
Changes to plasma/serum fatty acids were identified in both MCI and AD relative to age and gender matched controls .
Differences were greatest in AD , in both total number of fatty acids significantly altered , and the degree of change .
Docosahexaenoic acid  was lower in both MCI and AD , suggesting that it may be a driver of pathology