***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: Heterogeneity of executive tasks has made it difficult to determine whether there are age-related declines in executive functioning . To address this issue , 112 individuals , 20 - 79 years old , took the California Trail Making Test ( CTMT ) and the California Stroop Test ( CST ) , subtests of the Delis-Kaplan Executive Function Scale ( D. C. Delis , E. Kaplan , & J. H. Kramer , in press ) that include measurement of component skills embedded in the executive function tasks . Multiple regression analyses revealed that after controlling for component skills , age had a significant effect on the executive requirement of the CST , namely speed on the interference condition . Age did not affect switching performance on the letter-number condition of the CTMT . Additional analyses revealed that age was significantly associated with commission of certain types of errors . This study confirms the importance of partialing out components in the assessment of multidimensional cognitive tasks , particularly when making age comparisons . It also emphasizes specificity over generalizability when examining the impact of age on cognition 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 Deficits in visual cognition in Alzheimer 's disease ( AD ) arise from neuropathological changes in higher-order association areas of the cortex and from defective input from lower-level visual processing areas . We investigated whether enhanced signal strength may lead to improvement of visual cognition in AD . We tested 35 individuals with probable AD , 35 age-matched elderly control ( EC ) and 58 young control ( YC ) adults on  letter identification , word reading , picture naming , discrimination of unfamiliar faces , and pattern completion . The contrast sensitivity step-difference across an independent sample of AD and EC groups was used in calculating an image filter , from which we produced stimulus-strength conditions of low-de grade d , medium-normal , and high-enhanced . Using this filter we created a hypothetical proximal-strength equivalence between AD at medium strength and EC at low strength , and between AD at high strength and EC at medium strength . For letter identification , word reading , picture naming , and face discrimination , medium strength elicited AD accuracy levels and reaction times that were similar to those of EC at low strength . On picture naming , increased strength reduced perceptual-type errors for EC and AD and r and om errors for AD . For word reading , high strength elicited AD accuracy levels and reaction times that were equivalent to those of EC at medium strength . We saw no effect of signal-strength manipulation on performance of pattern completion , possibly owing to the complex cognitive dem and s of that task or to the inadequacy of the filter for its images . The results indicate that putative AD-EC differences in cognition directly reflect contrast sensitivity differences between the groups . Enhancement of stimulus strength can ameliorate vision-based deficits and lead to improvement in some aspects of cognitive performance . These results suggest new non-pharmacological avenues to explore in the attempt to improve cognition in elderly adults and especially in individuals with AD This individual differences study examined the separability of three often postulated executive functions-mental set shifting ( " Shifting " ) , information updating and monitoring ( " Updating " ) , and inhibition of prepotent responses ("Inhibition")- and their roles in complex " frontal lobe " or " executive " tasks . One hundred thirty-seven college students performed a set of relatively simple experimental tasks that are considered to predominantly tap each target executive function as well as a set of frequently used executive tasks : the Wisconsin Card Sorting Test ( WCST ) , Tower of Hanoi ( TOH ) , r and om number generation ( RNG ) , operation span , and dual tasking .  Confirmatory factor analysis indicated that the three target executive functions are moderately correlated with one another , but are clearly separable . Moreover , structural equation modeling suggested that the three functions contribute differentially to performance on complex executive tasks . Specifically , WCST performance was related most strongly to Shifting , TOH to Inhibition , RNG to Inhibition and Updating , and operation span to Updating . Dual task performance was not related to any of the three target functions . These results suggest that it is important to recognize both the unity and diversity of executive functions and that latent variable analysis is a useful approach to study ing the organization and roles of executive functions BACKGROUND Modifiable vascular and lifestyle-related risk factors have been associated with dementia risk in observational studies . In the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability ( FINGER ) , a proof-of-concept r and omised controlled trial , we aim ed to assess a multidomain approach to prevent cognitive decline in at-risk elderly people from the general population . METHODS In a double-blind r and omised controlled trial we enrolled individuals aged 60 - 77 years recruited from previous national surveys . Inclusion criteria were CAIDE ( Cardiovascular Risk Factors , Aging and Dementia ) Dementia Risk Score of at least 6 points and cognition at mean level or slightly lower than expected for age . We r and omly assigned participants in a 1:1 ratio to a 2 year multidomain intervention ( diet , exercise , cognitive training , vascular risk monitoring ) , or a control group ( general health advice ) . Computer-generated allocation was done in blocks of four ( two individuals r and omly allocated to each group ) at each site . Group allocation was not actively disclosed to participants and outcome assessors were masked to group allocation . The primary outcome was change in cognition as measured through comprehensive neuropsychological test battery ( NTB ) Z score . Analysis was by modified intention to treat ( all participants with at least one post-baseline observation ) . This trial is registered at Clinical Trials.gov , number NCT01041989 . FINDINGS Between Sept 7 , 2009 , and Nov 24 , 2011 , we screened 2654 individuals and r and omly assigned 1260 to the intervention group ( n=631 ) or control group ( n=629 ) . 591 ( 94 % ) participants in the intervention group and 599 ( 95 % ) in the control group had at least one post-baseline assessment and were included in the modified intention-to-treat analysis . Estimated mean change in NTB total Z score at 2 years was 0·20 ( SE 0·02 , SD 0·51 ) in the intervention group and 0·16 ( 0·01 , 0·51 ) in the control group . Between-group difference in the change of NTB total score per year was 0·022 ( 95 % CI 0·002 - 0·042 , p=0·030 ) . 153 ( 12 % ) individuals dropped out overall . Adverse events occurred in 46 ( 7 % ) participants in the intervention group compared with six ( 1 % ) participants in the control group ; the most common adverse event was musculoskeletal pain ( 32 [ 5 % ] individuals for intervention vs no individuals for control ) . INTERPRETATION Findings from this large , long-term , r and omised controlled trial suggest that a multidomain intervention could improve or maintain cognitive functioning in at-risk elderly people from the general population . FUNDING Academy of Finl and , La Carita Foundation , Alzheimer Association , Alzheimer 's Research and Prevention Foundation , Juho Vainio Foundation , Novo Nordisk Foundation , Finnish Social Insurance Institution , Ministry of Education and Culture , Salama bint Hamdan Al Nahyan Foundation , Axa Research Fund , EVO funding for University Hospitals of Kuopio , Oulu , and Turku and for Seinäjoki Central Hospital and Oulu City Hospital , Swedish Research Council , Swedish Research Council for Health , Working Life and Welfare , and af Jochnick Foundation Objectives To provide estimates of survival after onset of dementia by age , sex , self reported health , disability , and severity of cognitive impairment . Design Analysis of participants from prospect i ve population based cohort study in 1991 - 2003 , with follow-up of dementia status in all individuals after two and six years ( in one centre ) and 10 years and in sub sample s additionally at six and eight years and mortality until 2005 . Setting Multicentre population based study in Engl and and Wales : two rural and three urban centres . Participants 438 participants who developed dementia from a population based study of 13 004 individuals aged 65 years and over drawn from primary care population registers . Main outcome measures Sociodemographic factors , cognitive function , specific health conditions , and self reported health collected at each interview . Cox ’s proportional hazards regression models were used to identify predictors of mortality from the selected variables in people who received diagnosis of dementia according the study ’s criteria . Results By December 2005 , 356 of the 438 ( 81 % ) participants who developed dementia during the study had died . Estimated median survival time from onset of dementia to death was 4.1 years ( interquartile range 2.5 - 7.6 ) for men and 4.6 years ( 2.9 - 7.0 ) for women . There was a difference of nearly seven years in survival between the younger old and the oldest people with dementia : 10.7 ( 25th centile 5.6 ) for ages 65 - 69 ; 5.4 ( interquartile range 3.4 - 8.3 ) for ages 70 - 79 ; 4.3 ( 2.8 - 7.0 ) for ages 80 - 89 , and 3.8 ( 2.3 - 5.2 ) years for ages ≥90 . Significant factors that predicted mortality in the presence of dementia during the follow-up included sex , age of onset , and disability . Conclusion These analyses give a population based estimated median survival for incident dementia of 4.5 years . Such estimates can be used for prognosis and planning for patients , carers , service providers , and policy makers Objectives : To provide up date d estimates of Alzheimer disease ( AD ) dementia prevalence in the United States from 2010 through 2050 . Methods : Probabilities of AD dementia incidence were calculated from a longitudinal , population -based study including substantial numbers of both black and white participants . Incidence probabilities for single year of age , race , and level of education were calculated using weighted logistic regression and AD dementia diagnosis from 2,577 detailed clinical evaluations of 1,913 people obtained from stratified r and om sample s of previously disease-free individuals in a population of 10,800 . These were combined with US mortality , education , and new US Census Bureau estimates of current and future population to estimate current and future numbers of people with AD dementia in the United States . Results : We estimated that in 2010 , there were 4.7 million individuals aged 65 years or older with AD dementia ( 95 % confidence interval [ CI ] = 4.0–5.5 ) . Of these , 0.7 million ( 95 % CI = 0.4–0.9 ) were between 65 and 74 years , 2.3 million were between 75 and 84 years ( 95 % CI = 1.7–2.9 ) , and 1.8 million were 85 years or older ( 95 % CI = 1.4–2.2 ) . The total number of people with AD dementia in 2050 is projected to be 13.8 million , with 7.0 million aged 85 years or older . Conclusion : The number of people in the United States with AD dementia will increase dramatically in the next 40 years unless preventive measures are developed The hypothesis is tested that the response to dextroamphetamine in terms of activity , attention , impulsivity , and autonomic activity is similar in normal ( N ) and hyperactive ( H ) children . Fourteen N and 15 H boys had skin conductance ( SC ) , heart rate ( HR ) , and finger temperature ( ST ) recorded during rest , presentation of eight 75- dB tones , and a reaction time ( RT ) procedure on three occasions : off drug ( Day 1 ) and after ingestion ( double-blind ) of placebo and of .5 mg/kg dextroamphetamine . Both N and H groups showed drug effects , compared to placebo , of reduced motor activity and impulsivity , improved attention ( RT ) , increased HR and HR slowing during R 
    Output:
    
The study highlighted the importance of using st and ard protocol s to evaluate executive dysfunction in Alzheimer 's disease .
The  Stroop task allows discriminating better between healthy and pathological aging