***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: CONTEXT Many observational studies have shown that physical activity reduces the risk of cognitive decline ; however , evidence from r and omized trials is lacking . OBJECTIVE To determine whether physical activity reduces the rate of cognitive decline among older adults at risk . DESIGN AND SETTING R and omized controlled trial of a 24-week physical activity intervention conducted between 2004 and 2007 in metropolitan Perth , Western Australia . Assessors of cognitive function were blinded to group membership . PARTICIPANTS We recruited volunteers who reported memory problems but did not meet criteria for dementia . Three hundred eleven individuals aged 50 years or older were screened for eligibility , 89 were not eligible , and 52 refused to participate . A total of 170 participants were r and omized and 138 participants completed the 18-month assessment . INTERVENTION Participants were r and omly allocated to an education and usual care group or to a 24-week home-based program of physical activity . MAIN OUTCOME MEASURE Change in Alzheimer Disease Assessment Scale-Cognitive Subscale ( ADAS-Cog ) scores ( possible range , 0 - 70 ) over 18 months . RESULTS In an intent-to-treat analysis , participants in the intervention group improved 0.26 points ( 95 % confidence interval , -0.89 to 0.54 ) and those in the usual care group deteriorated 1.04 points ( 95 % confidence interval , 0.32 to 1.82 ) on the ADAS-Cog at the end of the intervention . The absolute difference of the outcome measure between the intervention and control groups was -1.3 points ( 95 % confidence interval,-2.38 to -0.22 ) at the end of the intervention . At 18 months , participants in the intervention group improved 0.73 points ( 95 % confidence interval , -1.27 to 0.03 ) on the ADAS-Cog , and those in the usual care group improved 0.04 points ( 95 % confidence interval , -0.46 to 0.88 ) . Word list delayed recall and Clinical Dementia Rating sum of boxes improved modestly as well , whereas word list total immediate recall , digit symbol coding , verbal fluency , Beck depression score , and Medical Outcomes 36-Item Short-Form physical and mental component summaries did not change significantly . CONCLUSIONS In this study of adults with subjective memory impairment , a 6-month program of physical activity provided a modest improvement in cognition over an 18-month follow-up period . TRIAL REGISTRATION anzctr.org.au Identifier : ACTRN12605000136606 BACKGROUND Cognitive decline among seniors is a pressing health care issue . Specific exercise training may combat cognitive decline . We compared the effect of once-weekly and twice-weekly resistance training with that of twice-weekly balance and tone exercise training on the performance of executive cognitive functions in senior women . METHODS In this single-blinded r and omized trial , 155 community-dwelling women aged 65 to 75 years living in Vancouver were r and omly allocated to once-weekly ( n = 54 ) or twice-weekly ( n = 52 ) resistance training or twice-weekly balance and tone training ( control group ) ( n = 49 ) . The primary outcome measure was performance on the Stroop test , an executive cognitive test of selective attention and conflict resolution . Secondary outcomes of executive cognitive functions included set shifting as measured by the Trail Making Tests ( parts A and B ) and working memory as assessed by verbal digit span forward and backward tests . Gait speed , muscular function , and whole-brain volume were also secondary outcome measures . RESULTS Both resistance training groups significantly improved their performance on the Stroop test compared with those in the balance and tone group ( P < or = .03 ) . Task performance improved by 12.6 % and 10.9 % in the once-weekly and twice-weekly resistance training groups , respectively ; it deteriorated by 0.5 % in the balance and tone group . Enhanced selective attention and conflict resolution was significantly associated with increased gait speed . Both resistance training groups demonstrated reductions in whole-brain volume compared with the balance and tone group at the end of the study ( P < or = .03 ) . CONCLUSION Twelve months of once-weekly or twice-weekly resistance training benefited the executive cognitive function of selective attention and conflict resolution among senior women . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00426881 BACKGROUND Cognitive impairment that does not meet the criteria for dementia ( " Cognitive Impairment , No Dementia " -- CIND ) is a heterogeneous category with an increased risk of dementia . While greater physical activity is generally associated with a lower odds of both dementia and CIND , whether this effect applies across subgroups is not known . OBJECTIVES To investigate the association between physical activity and the risk of vascular CIND ( VCI-ND ) or mild cognitive impairment ( MCI ) . METHODS In the Canadian Study of Health and Aging community-dwelling cohort , of 4683 people who were not impaired at baseline , 3945 remained without cognitive impairment at 5 years , 454 were diagnosed with CIND , and 284 with dementia . Incident CIND and VCI-ND ( n=163 ) and MCI ( n=100 ) subtypes were investigated in relation to baseline physical activity , stratified by sex . RESULTS In women , moderate-high exercise was associated with a lower odds of CIND ( OR=0.62 , 95 % CI=0.46 - 0.84 ) and VCI-ND ( 0.34 , 0.18 - 0.63 ) relative to low exercise . There was no association for men or for MCI . CONCLUSION Exercise appears to reduce the risk of VCI-ND in women . Whether the lack of an effect of exercise on the odds of MCI reflects that ' prevented AD ' is indistinguishable from MCI is an intriguing possibility that merits further study OBJECTIVES To examine the effects of aerobic exercise on cognition and other biomarkers associated with Alzheimer disease pathology for older adults with mild cognitive impairment , and assess the role of sex as a predictor of response . DESIGN Six-month , r and omized , controlled , clinical trial . SETTING Veterans Affairs Puget Sound Health Care System clinical research unit . PARTICIPANTS Thirty-three adults ( 17 women ) with amnestic mild cognitive impairment ranging in age from 55 to 85 years ( mean age , 70 years ) . Intervention Participants were r and omized either to a high-intensity aerobic exercise or stretching control group . The aerobic group exercised under the supervision of a fitness trainer at 75 % to 85 % of heart rate reserve for 45 to 60 min/d , 4 d/wk for 6 months . The control group carried out supervised stretching activities according to the same schedule but maintained their heart rate at or below 50 % of their heart rate reserve . Before and after the study , glucometabolic and treadmill tests were performed and fat distribution was assessed using dual-energy x-ray absorptiometry . At baseline , month 3 , and month 6 , blood was collected for assay and cognitive tests were administered . MAIN OUTCOME MEASURES Performance measures on Symbol-Digit Modalities , Verbal Fluency , Stroop , Trails B , Task Switching , Story Recall , and List Learning . Fasting plasma levels of insulin , cortisol , brain-derived neurotrophic factor , insulinlike growth factor-I , and beta-amyloids 40 and 42 . RESULTS Six months of high-intensity aerobic exercise had sex-specific effects on cognition , glucose metabolism , and hypothalamic-pituitary-adrenal axis and trophic activity despite comparable gains in cardiorespiratory fitness and body fat reduction . For women , aerobic exercise improved performance on multiple tests of executive function , increased glucose disposal during the metabolic clamp , and reduced fasting plasma levels of insulin , cortisol , and brain-derived neurotrophic factor . For men , aerobic exercise increased plasma levels of insulinlike growth factor I and had a favorable effect only on Trails B performance . CONCLUSIONS This study provides support , using rigorous controlled methodology , for a potent nonpharmacologic intervention that improves executive control processes for older women at high risk of cognitive decline . Moreover , our results suggest that a sex bias in cognitive response may relate to sex-based differences in glucometabolic and hypothalamic-pituitary-adrenal axis responses to aerobic exercise The hippocampus shrinks in late adulthood , leading to impaired memory and increased risk for dementia . Hippocampal and medial temporal lobe volumes are larger in higher-fit adults , and physical activity training increases hippocampal perfusion , but the extent to which aerobic exercise training can modify hippocampal volume in late adulthood remains unknown . Here we show , in a r and omized controlled trial with 120 older adults , that aerobic exercise training increases the size of the anterior hippocampus , leading to improvements in spatial memory .  Exercise training increased hippocampal volume by 2 % , effectively reversing age-related loss in volume by 1 to 2 y. We also demonstrate that increased hippocampal volume is associated with greater serum levels of BDNF , a mediator of neurogenesis in the dentate gyrus . Hippocampal volume declined in the control group , but higher preintervention fitness partially attenuated the decline , suggesting that fitness protects against volume loss . Cau date nucleus and thalamus volumes were unaffected by the intervention . These theoretically important findings indicate that aerobic exercise training is effective at reversing hippocampal volume loss in late adulthood , which is accompanied by improved memory function We report secondary findings from a r and omized controlled trial on the effects of exercise on memory in older adults with probable MCI . We r and omized 86 women aged 70–80 years with subjective memory complaints into one of three groups : resistance training , aerobic training , or balance and tone ( control ) .  All participants exercised twice per week for six months . We measured verbal memory and learning using the Rey Auditory Verbal Learning Test ( RAVLT ) and spatial memory using a computerized test , before and after trial completion . We found that the aerobic training group remembered significantly more items in the loss after interference condition of the RAVLT compared with the control group after six months of training . In addition , both experimental groups showed improved spatial memory performance in the most difficult condition where they were required to memorize the spatial location of three items , compared with the control group . Lastly , we found a significant correlation between spatial memory performance and overall physical capacity after intervention in the aerobic training group . Taken together , our results provide support for the prevailing notion that exercise can positively impact cognitive functioning and may represent an effective strategy to improve memory in those who have begun to experience cognitive decline Self-reported rates of participation in sport vary by country . In the UK , about 40 % of men and women aged 16 years or older participate in at least one sport every week . Although few data exist to assess trends for participation in sport , there is little evidence of change in the past decade among adults . Large cohort studies suggest that such participation in sport is associated with a 20 - 40 % reduction in all-cause mortality compared with non-participation . R and omised trials and crossover clinical studies suggest that playing sport is associated with specific health benefits . Some sports have relatively high injury risk although neuromuscular training programmes can prevent various lower extremity injuries . Clinicians can influence a large number of patients through brief interventions that promote physical activity , and encouragement toward participation in sport for some physically inactive patients qualifies as evidence -based therapy . Exercise might also be considered as a fifth vital sign and should be recorded in patients ' electronic medical records and routine histories 
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Adding fuel to the fire are publications such as a 2013 systematic review of r and omised controlled trials ( RCTs ) ( prior to 31 October 2011 ) reporting ‘ weak ’ evidence for the effects of exercise on cognition.4 We must highlight that the search strategy used in that systematic review failed to capture many pertinent papers providing evidence from RCTs that exercise  promotes cognitive and brain plasticity not only in healthy older adults but also in those with cognitive impairment .