Age-related changes in cognitive domains. A population-based study

Subclinical HMOD in Hypertension: Brain Imaging and Cognitive Function

Latest European Societies of Hypertension and Cardiology (ESH/ESC) have acknowledged that brain represent a relevant target for hypertension mediated organ damage (HMOD). In fact, brain damage can be the only HMOD in more than 30% of hypertensive subjects, evolving undetected for several years if not appropriately screened. However, no clear position has been indicated on how to evaluate brain HMOD. The present manuscript would contribute to briefly summarize structural and functional brain HMOD for the medical community dealing with older hypertensive patients. Arterial aging is proposed as possible "common soil" underlying structural and functional brain HMOD. Finally, a simple algothythm to screen older hypertensive subjects for cognitive function is proposed and discussed.

APOE Variant (rs405509) might Modulate the Effect of Sex and Educational Level on Cognitive Impairment Risk in a Taiwanese Population

Education, sex, and the APOE-rs405509 variant are associated with Alzheimer’s disease and cognitive performance. We investigated if the rs405509 TT, TG, and GG genotypes modulate the effect of sex and education on cognitive impairment in Taiwanese adults. Data on cognitive health (defined by Mini-Mental State Examination (MMSE) scores) and rs405509 were from Taiwan Biobank. Participants included 2105 men and 2027 women with a mean age of 64 years. Education below university level was significantly associated with lower MMSE scores. The odds ratios (ORs) were 1.82; 95% confidence interval (CI) 1.38–2.41 for senior high school, 3.39; 95% CI 2.50–4.59 for junior high school, and 11.94; 95% CI 9.91–15.50 for elementary school and below (p-trend < 0.05). The association between MMSE score and sex was significant only in the lowest educational group (elementary and below), with lower odds of having a low MMSE score in men compared to women (OR = 0.51; 95% CI 0.34–0.77). After stratification by rs405509 genotypes, this association was significant only among TT genotype carriers (OR = 0.481; CI = 0.253–0.915). In conclusion, a significant association between MMSE score and sex was observed in the lowest educational group, especially among carriers of rs405509 TT genotypes.

Common Carotid Artery Calcification Impacts on Cognitive Function in Older Patients

INTRODUCTION

Cognitive impairment and dementia represent an emerging health problem. Cardiovascular (CV) risk factors contribute to cognitive impairment.

AIM

To investigate the effect of vascular calcification on cognitive impairment and dementia, independently of plaque and traditional CV risk factors.

METHODS

Four hundred and sixty-nine patients (age of 78.6 ± 6.1 years, 74.4% women) were studied. Traditional CV risk factors levels, cognitive function (MMSE), brain CT scan, and other vascular parameters were measured. Common Carotid Artery (CCA) plaque and calcification were evaluated by ultrasound.

RESULTS

CCA calcification was associated with a lower MMSE score than in subjects with no CCA calcification (23.7 ± 0.3 versus 25.5 ± 0.8; p = 0.015), after controlling for age, sex, education, blood pressure levels, diabetes, creatinine, lipid lowering therapy, neuroimaging alteration, and CCA plaque. Similarly, CCA calcification was associated with higher odds of dementia regardless of the presence of CCA plaque (OR 1.70, 95% CI 1.01-2.94, p < 0.05). This trend was not observed when stratifying patients according to the presence of CCA plaque.

CONCLUSION

CCA calcification is associated with cognitive impairment and dementia, independently of established CV risk factors and CCA plaque. The impact of arterial calcification on cognition seems largely independent of arterial stiffness.

Guanfacine treatment for prefrontal cognitive dysfunction in older participants: a randomized clinical trial

This study evaluated the effect of the alpha-2A-adrenoceptor agonist guanfacine on prefrontally mediated cognitive functions, as well as quality of life and global function in healthy older participants. One hundred twenty-three participants aged 75 years and older were randomly assigned to guanfacine 0.5 mg, 0.1 mg, or placebo daily for 12 weeks. The primary outcome measure was the change in z-score for 6 prefrontal executive function tasks over 12 weeks (PEF6). Neither dose of guanfacine improved PEF6 z-score relative to placebo. The rate of mean change (95% confidence interval) in PEF6 z-score over 12 weeks was 0.270 (0.159, 0.380) for placebo, compared with 0.121 (0.011, 0.232) for guanfacine 0.1 mg (p = 0.06, compared to placebo) and 0.213 (0.101, 0.324) for 0.5 mg (p = 0.47). Neither dose of guanfacine improved the quality of life or global function relative to placebo. Among common adverse events, only dry mouth was significantly more frequent on guanfacine compared to placebo. Guanfacine failed to ameliorate prefrontal cognitive function in older individuals, who were cognitively normal for age.

Memory and Executive Screening for the Detection of Cognitive Impairment in Obstructive Sleep Apnea

BACKGROUND

Obstructive sleep apnea (OSA) is commonly associated with cognitive dysfunction, which is more apparent in severe OSA and impairs quality of life. However, the clinical screening methods for these impairments in OSA are still limited. In this study, we evaluated the feasibility of using the Memory and Executive Screening (MES) for assessing cognitive performance in OSA.

MATERIALS AND METHODS

Twenty-four patients with nonsevere OSA and 36 patients with severe OSA participated in this study. All participants underwent comprehensive, laboratory-based polysomnography and completed assessments of cognitive function, which included both the MES and the Beijing version of the Montreal Cognitive Assessment (MoCA-BJ).

RESULTS

Both the total MES scores and 5 recall scores of the MES (MES-5R) were significantly lower in the severe OSA group than those in the nonsevere OSA group. The patients with severe OSA performed worse on the memory subtests of the MES-5R, especially on immediate recall. The sensitivity and specificity of the MES for identifying cognitive impairment in patients with OSA were 63.89% and 66.67%, respectively, for a cutoff value of <92 out of 100 points. An optimal cutoff between nonsevere and severe OSA was also set at 45 points (MES-5R) and at 0.94 points (MES ratio). Compared with the MES, the MoCA-BJ had similar sensitivity (61.11%) and specificity (66.67%).

CONCLUSIONS

The MES is an acceptable tool for detecting cognitive dysfunction in patients with OSA. The sensitivity and specificity of the MES were similar to those of the MoCA-BJ. The MES-5R and total MES scores can assess the presence and severity of cognitive impairment in patients with severe OSA.

Association Between Executive Functions, Working Memory, and Manual Dexterity in Young and Healthy Older Adults: An Exploratory Study

Aging is accompanied by declines in cognitive and sensorimotor functions. However, at present, the interrelation between attentional processes and dexterity in aging has not been thoroughly addressed. This study explored the relationship between executive function, working memory, and dexterity performance in 15 young and 15 healthy elderly, right-handed participants. A modified version of the Purdue Pegboard Test was used for dexterity assessment. Two subtasks were selected to calculate temporal and kinematic parameters of reaching, grasping, transport, and insertion of pegs. Evaluation of executive function and working memory was performed using neuropsychological tests. The relationship between dexterity and cognitive outcomes were also examined. Results showed that the prehensile movements involved in grasping and their speed significantly differed between groups and correlated with executive function in the young group. For elderly adults, variability of hand movements turned out to be associated with executive abilities.

Visually encoded working memory is closely associated with mobility in older adults

Previous research suggests that older adults' motor performance is associated with cognitive function. Although this has been reported especially for executive function, it is not yet clear for various types of working memory (WM). In fact, age-related decline in WM is more severe for faces than other types of visual objects. The present study focused on the relationship between diverse WM and two types of motor performance (mobility and manual dexterity), which are implicated in pathological decline. To measure diverse WM, we adopted N-back tasks using three distinct types of stimuli (numbers, locations, and faces). Mobility was measured with the timed up and go test and manual dexterity was measured with the Pegboard Test. Participants were community-dwelling older adults (age: mean 78.6 years). Comparisons of younger and older adults' N-back performances indicated that WM for faces is more sensitive to aging compared with WM for the other stimuli. Correlation analyses within the older group indicated that WM tasks mainly correlated with mobility, but less so with manual dexterity. Among the three types of WM, spatial WM and face WM had significant partial correlation coefficients with mobility after age and general cognitive decline were controlled. These results indicate that visually encoded WM is associated only with mobility, although general cognitive function is related to both motor abilities. The selective association between the visually encoded WM and mobility is discussed in terms of the interactive processes between executive processing and perceptual encoding, where dynamic visual processing for locomotion plays a role.

Aortic stiffness and hypotension episodes are associated with impaired cognitive function in older subjects with subjective complaints of memory loss

OBJECTIVE

Though CV risk factors and markers of arterial aging are recognized risky for cognition, no study has simultaneously investigated the impact of multiple cardiac, arterial (large and small vessels), and hemodynamic parameters on cognitive function in older subjects.

METHODS

Two hundred eighty older subjects with subjective complaints of memory loss and no previous stroke (mean age 78.3 ± 6.3 years) were studied. Global cognitive function was evaluated with the Mini-Mental State Examination (MMSE). Cognitive impairment was defined as a MMSE < 21. We measured: traditional CV risk factors; aorta stiffness (Pulse Wave Velocity, PWV); LV mass; presence of WML at neuroimaging; episodes of hypotension (SBP <100 mmHg during 24 h Ambulatory Blood Pressure Monitoring).

RESULTS

In both cross-sectional and longitudinal analyses PWV, WML, and episodes of hypotension were significantly associated with poorer cognitive function-controlling for age, sex, education, depression, traditional CV risk factors, and medications. LV mass was no longer associated with cognition in multiple regression. Older subjects with stiffer arteries or episodes of hypotension presented a 4-fold and an 11-fold, respectively, greater odds for progression from normal cognitive function to cognitive impairment. A synergistic effect between PWV, WML, and hypotension was observed: the occurrence of any two of PWV, WML, or hypotension was accompanied by lower MMSE; in the presence of all three factors, a further significant decline in cognitive function was observed.

INTERPRETATION

Systemic hemodynamic parameters (higher PWV and hypotension) together with cerebral microvascular damage (WML) are significantly associated with poorer cognitive function and may identify older subjects with subjective complaints of memory loss at higher risk of cognitive decline.

Relationship between left atrial volume index and cognitive decline in elderly patients with sinus rhythm

Left atrial (LA) enlargement is a predictor of cardiovascular outcomes such as atrial fibrillation (AF), stroke, and death. The aim of this study was to explore the relationship between LA size and cognitive function in elderly patients without any signs of clinical dementia, AF or previous stroke. We assessed the cognitive status and LA volume (LAV) of 108 consecutive patients (27 males; mean age, 74.8 ± 6.9 years) with sinus rhythm. Cognitive status was assessed by the Mini Mental State Examination (MMSE). Patients with a MMSE score of ≤25 were considered to have cognitive impairment. LAV was measured with two-dimensional echocardiography. LAV index (LAVI) was obtained by indexing LAV to body surface area. Thirty-five patients (32.4%) had cognitive impairment. The patients with cognitive impairment had significantly larger left atria than the patients with normal cognitive function. Receiver operating characteristic analysis revealed a cut-off point of ≥ 34 mL/m(2) for LAVI to predict patients with cognitive impairment (sensitivity, 97.1%; specificity, 52.1%; positive predictive value, 49.3%; negative predictive value, 97.4%). LAVI ≥34 mL/m(2) was significantly associated with cognitive impairment (p = 0.001, odds ratio = 36.91, 95% confidence interval = 4.8-284.2). Logistic regression analysis revealed that LAVI ≥ 34 mL/m(2) and age were independently associated with cognitive impairment. Increased LAVI is associated with cognitive impairment. Assessment of cognitive function may be recommended in elderly patients with enlarged left atria.

Memory and Executive Screening (MES): a brief cognitive test for detecting mild cognitive impairment

Background

Mild cognitive impairment (MCI), defined as a transitional zone between normal cognition and dementia, requires a battery of formal neuropsychological tests administered by a trained rater for its diagnosis. The objective of this study was to develop a screening tool for MCI.

Methods

One hundred ninety seven cognitively normal controls (NC), one hundred sixteen patients with amnestic MCI –single domain (aMCI-sd), one hundred ninety five patients with amnestic MCI-multiple domain (aMCI-md), and two hundred twenty eight patients with mild Alzheimer’s disease (AD) were evaluated by comprehensive neuropsychological tests and by the Memory and Executive Screening (MES).

Results

Correlation analysis showed that the three indicators of the MES were significantly negatively related with age (P<0.05), yet not related with education (P>0.05). There was no ceiling or floor effect. Test completion averaged seven minutes (421.14±168.31 seconds). The receiver operating characteristics (ROC) analyses performed on the aMCI-sd group yielded 0.89 for the area under the curve (AUC) (95% CI, 0.85–0.92) for the MES-total score, with sensitivity of 0.795 and specificity of 0.828. There was 81% correct classification rate when the cut-off was set at less than 75. Meanwhile, the aMCI-md group yielded 0.95 for the AUC (95% CI, 0.93–0.97) for the MES-total score, with sensitivity of 0.87 and specificity of 0.91, and 90% correct classification rate when the cut-off was set at less than 72.

Conclusion

The MES, minimally time-consuming, may be a valid and easily administered cognitive screening tool with high sensitivity and specificity for aMCI, with single or multiple domain impairment.

Stress and cognitive function in Latino farmworkers

BACKGROUND

Job stress has been associated with cognitive function, but the relationship is often overlooked when considering occupational health and safety issues of farmworkers. This study examined the relationship between stress and change in stress with change in cognitive function in a representative sample of 123 Latino farmworkers.

METHODS

A prospective study design was used in which stress and cognitive function data were collected at baseline and at 3-month follow-up. Linear regression models were used for analyses. Potential confounders included baseline gender, age, education, number of years worked in U.S. agriculture, ever smoking status, self-rated health, and depressive symptoms.

RESULTS

Baseline stress was significantly correlated with baseline cognitive function (r = -0.27; P < 0.001). Adjusting for confounders, increased baseline stress was associated with greater decline in cognitive function (P = 0.024). Short-term changes in stress were not associated with cognitive change in this cohort.

CONCLUSIONS

Stress at work is an important risk factor for poor cognitive function. This analysis suggests several implications for the provision of health care and for the organization of work for farmworkers.

Clinical trials: new opportunities

Human cognitive aging has been too long neglected and underappreciated for its critical importance to quality of life in old age. The articles in this session present novel approaches to improving cognitive function in normal aging persons with drugs and interventions that are based on findings in epidemiology, studies in aged animals, and in vitro research. In addition, since aging is the primary risk factor for Alzheimer's disease, these studies also have implications as interventions for prevention and treatment. As a field of research, new knowledge regarding the causes and mechanisms of cognitive aging are ripe for translation into human studies, with the application of this knowledge leading the development of interventions and therapeutics for the prevention of cognitive decline in old age and Alzheimer's disease.

Bringing prevention in geriatrics: evidences from cardiovascular medicine supporting the new challenge

Aging is a dynamic and systemic process, with high inter-individual heterogeneity, likely partially adaptive. Cardiovascular disease and hypertension are among the leading conditions causing disabilities in older subjects. If, in accordance with most recent definition, prevention is any intervention before the patient receives a diagnosis, prevention is possible at any age. Additionally, disability and CV disease in the elderly may be prevented by targeting factors underlying and modulating the arterial aging process. Cross-talk between arterial and brain aging will be discussed in this context as a paradigmatic clinical model fostering prevention in older subjects.

Depressive symptoms and executive functioning in stroke patients: a follow-up study

BACKGROUND

Cognitive and emotional sequellae are commonly observed in stroke patients and these symptoms often co-occur. Diagnosis can be difficult since symptoms of depression and executive dysfunction overlap.

OBJECTIVE

To study the longitudinal relationship between depressive symptoms and executive dysfunction in stroke patients.

METHODS

The study comprises of 116 first-ever stroke patients who were followed-up for 2 years and who were assessed for emotional and cognitive sequellae after 1, 6, 12, and 24 months. Emotional disturbances were evaluated using the SCL-90 depression subscale. Executive functions were assessed using compound scores of a combination of the interference scores of the Stroop Colour Word Test and the Concept Shifting Test.

RESULTS

Twenty-five patients suffered from both depressive symptoms and executive dysfunction, 28 patients were depressed with no signs of executive dysfunction, and 13 patients showed executive dysfunction with no depressive symptoms. Patients with executive dysfunction had higher mean SCL-90-D scores compared to patients with no executive dysfunction (30.9 (SD 11.7) versus 26.2 (SD 11.1, p = 0.037). Depressive symptoms were predictive for executive dysfunction in a regression analysis corrected for age, sex, and diabetes mellitus but not after additional correction for pre-existent brain damage and other vascular risk factors. After 2 years 66.6 and 53.3% of patients with both depressive symptoms and executive dysfunction at baseline still had depressive symptoms and executive dysfunctions respectively and had worse prognostic outcome than patients with depressive symptoms or executive dysfunction alone.

CONCLUSIONS

Symptoms of depression and executive dysfunction are highly prevalent in stroke patients and often co-occur. These patients are more at risk for poor stroke outcome, chronic depression, and cognitive deterioration.

The relationship between education level and mini-mental state examination domains among older Mexican Americans

To study the effect of education and language of response at the interview on performance in the Mini-Mental State Examination (MMSE) domains, we studied 2861 Mexican Americans aged 65 and older from the Hispanic Established Populations for Epidemiologic Studies of the Elderly (EPESE) followed from 1993 to 1994 until 2004 to 2005. The MMSE was examined as total score (0-30) or divided into 2 global domains: (1) no-memory (score 0-24): Orientation, attention, and language; and (2) memory (score 0-6): working and delayed memory. Mean age and total MMSE were 72.7 years and 24.6 at baseline, and 81.7 years and 20.5 at 11 years of follow-up. Spanish-speaking participants had less education (4.1 vs 7.4 years, P < .0001), they had significantly higher adjusted mean scores for memory, no-memory, and total MMSE compared with English-speaking participants. In multivariate longitudinal analyses, participants with more years of education performed better than those with less education, especially in total MMSE and no-memory domain. Spanish-speaking participants with 4 to 6 years of education had higher memory scores than those speaking English (estimate 0.40, standard error [SE] = 0.14, P < .001), 7 to 11 (estimate 0.27, standard error = 0.13, P < .01) or 12+ (estimate 0.44, standard error = 0.13, P < .001). Results suggest that cultural factors and variables related to preferred language use determined variations in MMSE performance. Because the memory domain of the MMSE is less affected by education, it may be used along with other cognitive tests for early detection of cognitive decline in older populations with low education.

Quadriceps strength and executive functions in older women

OBJECTIVE

The aim of this study is to answer the question whether the strength of the knee extensor musculus quadriceps (m. quadriceps), in particular, is related to specific executive functions and whether this relationship is independent of aerobic fitness. The clinical relevance of this question is that the m. quadriceps can still be trained in older people and executive functions are the most vulnerable to processes of aging.

DESIGN

In 41 cognitively intact older women, cognitive functioning was assessed by neuropsychological tests; isometric and isotonic quadriceps strength by the Quadrisotester and the 30-sec chair-stand test, respectively; and aerobic fitness by the 6-min walk test.

RESULTS

A significant proportion of the total variance of the executive functions, attention/working memory and inhibition, were explained by isometric/isotonic knee extensor strength and aerobic fitness, respectively. Extensor muscle strength, aerobic fitness, or one or more interactions did not explain a significant proportion of the total variance of other cognitive functions.

CONCLUSIONS

These data suggest that in older women, quadriceps strength is associated with the executive function, attention/working memory, and that this effect is independent of aerobic fitness, which seems to be associated more strongly with inhibition, another executive function.

Depression, hypertension, and comorbidity: disentangling their specific effect on disability and cognitive impairment in older subjects

We aimed to demonstrate that depression and hypertension are associated independently of each other with disability and cognitive impairment in older subjects and that such an association is not attributable to number and severity of comorbidities. An observational study was performed on elderly patients admitted to the Hospital Network of the Italian National Research Center on Aging (INRCA) from January 2005 to December 2006. Depression was defined according to 15-item geriatric depression scale (GDS) score; physical disability according to activities of daily living (ADL) and instrumental activities of daily living (IADL) scores; cognitive impairment on the mini-mental state examination (MMSE) test; the number and severity of comorbidities by means of physician-administered cumulative illness rating scale (CIRS). Among 6180 older subjects (age=79.3 ± 5.8 years; 47% men), 48.3% were normotensive, 21.8% normotensive depressed, 21.7% hypertensive, and 8.2% hypertensive and depressed. Both depression and hypertension remained significantly associated with functional disability and cognitive impairment. When controlling for age, gender, the number and severity of comorbidities, hypertension was associated with a significantly higher likelihood of having functional disability or cognitive impairment only in the presence of depression (odds ratio=OR=2.02, 95% confidence interval=95%CI=1.60-2.54, p<0.001 for functional disability; OR=2.21, 95%CI=1.79-2.74, p<0.001 for cognitive impairment) as compared to normotensive controls without depression. We conclude that depression per se' or co-occurrence of hypertension and depression is associated with higher functional disability and cognitive impairment in older subjects. This effect is not attributable to the number or to the severity of comorbidities.

Evaluating arterial aging in the clinical setting: a tentative agenda for critical appraisal

Population aging is a worldwide phenomenon. However, the cultural attitude to older adults has not yet incorporated understanding of the effects of the aging process. The arterial system is affected by the aging process, which is responsible for the great majority of mortality, morbidity and disability in older people. We briefly describe how the aging process affects large arteries and their properties that are easily measurable noninvasively, and suggest a tentative agenda for solving the critical problems that have hampered the diffusion of routine assessment of arterial aging in the clinical setting.

[German adaptation of the "Activities-Specific Balance Confidence (ABC) scale" for the assessment of falls-related self-efficacy]

The present study investigates the psychometric properties and the factorial structure of the German adaptation of the Activities-Specific Balance Confidence (ABC) scale (Powell & Myers, 1995) for the evaluation of falls-related self-efficacy in community-dwelling older adults. The German adaptation of the ABC using a forward-backward procedure was administered to 113 older adults (age 68.9+/-8.5 years). The following internationally accepted instruments were used for validation: The Short Form Health Survey SF 36, the Geriatric Depression Scale (GDS), the Trail Making Test and the Letter Number Sequencing Test, and motor tests (balance, strength, mobility). The internal consistency (0.91-0.95) as well as the test-retest reliability of the subscales was excellent (0.94-0.98). The correlation coefficients with the validation instruments ranged between 0.33 and 0.58. Significant differences in the ABC-D scores were found in older adults with and without falls. Older adults with a recent fall history scored lower on the ABC-D than older adults without a recent fall history. To conclude, the German version of the ABC has properties analogous to the original English version and is apparently useful in assessing falls-related self-efficacy.

Age and educational level effects on the performance of normal elderly on category verbal fluency tasks

Cognitive decline, particularly executive dysfunction, is observed in normal aging. In Brazil, the elderly population presents broad educational diversity. Category verbal fluency tests are frequently used to detect cognitive impairment, assessing executive function, language and semantic memory.

Objective

To investigate the effects of age and education on category animal fluency task (CAF) in healthy elderly.

Methods

We evaluated 319 healthy elderly from outpatient care units of two university reference centers of Rio de Janeiro and São Paulo. The sample was divided into two age, and five schooling subgroups. To be included participants had to demonstrate preservation of global cognitive functioning, independence for activities of daily living and not fulfill diagnostic criteria for dementia. All participants were submitted to neurological and neuropsychological evaluations.

Results

There was a correlation between age and CAF performance (r= -0.26, p<0.01), which was not confirmed when years of education were included as a covariant in univariate ANCOVA. Significant differences were found in CAF performance among the different educational level groups on correlation analysis (r=0.42, p<0.01) and ANCOVA analysis (F=18.8, p<0.05). Illiteracy was associated with worst CAF performance, while university level was associated with best performance.

Conclusion

The best CAF performance was found in the first years of schooling (literacy learning process) compared to illiteracy, and when finishing high school and starting university courses compared to all other educational levels. These stages are associated with significant gains in semantic memory and executive function which are critical for verbal fluency performance.

Facilitating skilled right hand motor function in older subjects by anodal polarization over the left primary motor cortex

Healthy ageing is accompanied by limitations in performance of activities of daily living and personal independence. Recent reports demonstrated improvements in motor function induced by noninvasive anodal direct current stimulation (tDCS) of the primary motor cortex (M1) in young healthy adults. Here we tested the hypothesis that a single session of anodal tDCS over left M1 could facilitate performance of right upper extremity tasks required for activities of daily living (Jebsen-Taylor hand function test, JTT) in older subjects relative to Sham in a double-blind cross-over study design. We found (a) significant improvement in JTT function with tDCS relative to Sham that outlasted the stimulation period by at least 30 min, (b) that the older the subjects the more prominent this improvement appeared and (c) that consistent with previous results in younger subjects, these effects were not accompanied by any overt undesired side effect. We conclude that anodal tDCS applied over M1 can facilitate performance of skilled hand functions required for activities of daily living in older subjects.

Changes in cognition and mortality in relation to exercise in late life: a population based study

Background

On average, cognition declines with age but this average hides considerable variability, including the chance of improvement. Here, we investigate how exercise is associated with cognitive change and mortality in older people and, particularly, whether exercise might paradoxically increase the risk of dementia by allowing people to live longer.

Methods and Principal Findings

In the Canadian Study of Health and Aging (CSHA), of 8403 people who had baseline cognition measured and exercise reported at CSHA-1, 2219 had died and 5376 were re-examined at CSHA-2. We used a parametric Markov chain model to estimate the probabilities of cognitive improvement, decline, and death, adjusted for age and education, from any cognitive state as measured by the Modified Mini-Mental State Examination. High exercisers (at least three times per week, at least as intense as walking, n = 3264) had more frequent stable or improved cognition (42.3%, 95% confidence interval: 40.6–44.0) over 5 years than did low/no exercisers (all other exercisers and non exercisers, n = 4331) (27.8% (95% CI 26.4–29.2)). The difference widened as baseline cognition worsened. The proportion whose cognition declined was higher amongst the high exercisers but was more similar between exercise groups (39.4% (95% CI 37.7–41.1) for high exercisers versus 34.8% (95% CI 33.4–36.2) otherwise). People who did not exercise were also more likely to die (37.5% (95% CI 36.0–39.0) versus 18.3% (95% CI 16.9–19.7)). Even so, exercise conferred its greatest mortality benefit to people with the highest baseline cognition.

Conclusions

Exercise is strongly associated with improving cognition. As the majority of mortality benefit of exercise is at the highest level of cognition, and declines as cognition declines, the net effect of exercise should be to improve cognition at the population level, even with more people living longer.

Age-related cognitive deficits in rhesus monkeys mirror human deficits on an automated test battery

Aged non-human primates are a valuable model for gaining insight into mechanisms underlying neural decline with aging and during the course of neurodegenerative disorders. Behavioral studies are a valuable component of aged primate models, but are difficult to perform, time consuming, and often of uncertain relevance to human cognitive measures. We now report findings from an automated cognitive test battery in aged primates using equipment that is identical, and tasks that are similar, to those employed in human aging and Alzheimer's disease (AD) studies. Young (7.1+/-0.8 years) and aged (23.0+/-0.5 years) rhesus monkeys underwent testing on a modified version of the Cambridge Automated Neuropsychological Test Battery (CANTAB), examining cognitive performance on separate tasks that sample features of visuospatial learning, spatial working memory, discrimination learning, and skilled motor performance. We find selective cognitive impairments among aged subjects in visuospatial learning and spatial working memory, but not in delayed recall of previously learned discriminations. Aged monkeys also exhibit slower speed in skilled motor function. Thus, aged monkeys behaviorally characterized on a battery of automated tests reveal patterns of age-related cognitive impairment that mirror in quality and severity those of aged humans, and differ fundamentally from more severe patterns of deficits observed in AD.

Serum leptin levels are associated with cognitive function in older adults

Recent work suggests that leptin, a circulating adipokinine hormone, might contribute to age-related cognitive decline. The present study investigated the relationship between serum leptin levels and cognitive function in older adults. Thirty-five older adults (73.69+/-6.62 years of age) without significant neurologic or psychiatric history completed a fasting blood draw and a brief neuropsychological test battery. Partial correlations adjusting for demographic and medical conditions showed that higher leptin levels were associated with poorer performance on Trail Making Test B (r = .46, p = .01). These findings indicate that serum leptin levels are negatively associated with speeded executive function in older adults without significant neurological or psychiatric conditions. The mechanisms for this relationship are unknown and require further examination. Such studies may provide key insight into the mechanisms of age-related cognitive decline and identify possible interventions.