Associations between circulating cardiovascular disease risk factors and cognitive performance in cognitively healthy older adults from the NuAge study.

Introduction: Cardiovascular disease risk factors (CVRFs) contribute to the development of cognitive impairment and dementia. Methods: This study examined the associations between circulating CVRF biomarkers and cognition in 386 cognitively healthy older adults (mean age = 78 ± 4 years, 53% females) selected from the Quebec Longitudinal Study on Nutrition and Successful Aging (NuAge). Memory, executive function, and processing speed were assessed at baseline and 2-year follow-up. CVRF biomarkers included total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), triglycerides, glucose, insulin, high sensitivity C-reactive protein (hs-CRP), homocysteine, protein carbonyls, and cortisol. Linear mixed models were used to determine associations between individual CVRF biomarkers and cognition at both time points. Results: HDL-C was most consistently associated with cognition with higher values related to better performance across several domains. Overall, stronger and more consistent relationships between CVRF biomarkers and cognition were observed in females relative to males. Discussion: Findings suggest that increases in the majority of circulating CVRFs are not associated with worse cognition in cognitively healthy older adults.

Household physical activity is positively associated with gray matter volume in older adults.

BACKGROUND: Total physical activity is positively associated with brain volume and cognition in older adults. While we have ample evidence that recreational physical activity influences brain health, the contributions of other daily activities are less understood. In particular, the associations between household physical activity and brain health in older adults is underexplored. The purpose of this study was to identify associations between household physical activity, brain volume, and cognition in a sample of cognitively unimpaired older adults. METHODS: We report data from 66 cognitively unimpaired older adults (71 ± 4 years) who participated in a health evaluation, cognitive assessment, and structural brain imaging. Physical activity was assessed using the Phone-FITT questionnaire and separated into household and recreational physical activity. We quantified whole brain volume, gray matter volume, and white matter volume, and assessed cognitive performance in four domains: memory, working memory/attention, processing speed, and executive function. Associations between physical activity, brain volume, and cognition were investigated in an omnibus approach using two multivariate analysis of variance (MANOVA) models. The first model assessed the associations between physical activity and brain volume adjusting for age, sex, Framingham Risk score (FRS) and intracranial volume. The second model assessed the associations between physical activity and overall cognitive performance adjusting for age, sex, FRS and education. Post hoc regression analyses were conducted to investigate significant MANOVA results. We also conducted further regression analyses to investigate associations with hippocampal and frontal lobe volume. RESULTS: Household, but not recreational, physical activity was positively associated with brain volume measurements (F = 3.07, p = .035), specifically gray matter volume (t = 2.51, p = .015). Further exploratory analyses identified that household physical activity was associated with hippocampal (p = .015) and frontal lobe (p = .010) volume. No significant relationships were observed between household or recreational physical activity and cognition. CONCLUSION: Time spent engaging in household physical activity was positively associated with brain volume, specifically gray matter volume, in older adults. Highlighting the benefits associated with household chores may motivate older adults to be more active by providing a more attainable, low risk form of physical activity.

The Association Between Dietary Pattern Adherence, Cognitive Stimulating Lifestyle, and Cognitive Function Among Older Adults From the Quebec Longitudinal Study on Nutrition and Successful Aging.

OBJECTIVES: This study examined the effect of dietary patterns and engagement in cognitive stimulating lifestyle (CSL) behaviors on the trajectory of global cognition, executive function (EF), and verbal episodic memory (VEM). METHODS: Western and prudent dietary patterns were empirically derived using food frequency questionnaire responses from 350 community-dwelling older adults (mean age: 73.7 years) participating in the Quebec Longitudinal Study on Nutrition and Successful Aging. CSL was represented by a binary composite indicator based on education, occupational complexity, and social engagement. Global cognition, EF, and VEM were assessed prospectively. RESULTS: Primary effect models revealed an association between higher Western dietary pattern score and a greater rate of decline in global cognition and EF. Higher Western dietary pattern adherence was also associated with poorer baseline VEM. Primary effect models also revealed that CSL was independently associated with baseline global cognition and EF. Effect modification models suggested an interactive effect between Western dietary pattern and CLS on global cognition only. No associations were found for prudent dietary pattern score. DISCUSSION: Contributing to existing research supporting the negative impact of consuming an unhealthy diet on cognitive function, the current study suggests increased vulnerability among older adults who do not engage in a CSL. These findings can inform the development of lifestyle intervention programs that target brain health in later adulthood.

Lower Thalamic Blood Flow Is Associated With Slower Stride Velocity in Older Adults.

BACKGROUND: Gait deficits are associated with brain atrophy and white matter hyperintensities (WMH) - both markers of underlying cerebral small vessel disease (SVD). Given reduced subcortical cerebral blood flow (CBF) is prevalent in SVD, we tested the hypothesis that regional CBF is positively associated with gait performance among older adults. METHODS: Thirty-two older adults (55-80 years) with at least one vascular risk factor were recruited. We assessed gait during 2 consecutive walking sequences using a GAITRite system: (1) at a self-selected pace, and (2) while performing a serial subtraction dual-task challenge. We quantified CBF using pseudo-continuous arterial spin labeling MRI within 4 regions of interest: putamen, pallidum, thalamus, and hippocampus. We investigated associations between gait characteristics and overall CBF adjusting for age, sex, and height in an omnibus approach using multivariate analysis of variance, followed by regression analysis with each individual region. We also conducted further regression analyses to investigate associations between gait characteristics and frontal lobe CBF. Sensitivity analyses examined how the observed associations were modified by WMH, executive function, and depressive symptoms. A change of 10% in the model's adjusted r2 and effect size was considered as a threshold for confounding. RESULTS: Overall subcortical CBF was not associated with self-paced gait. When examining individual ROI, gait velocity was directly related to thalamic CBF (p = 0.026), and across all gait variables the largest effect sizes were observed in relation to thalamic CBF. In the dual-task condition, gait variables were not related to CBF in either the omnibus approach or individual multiple regressions. Furthermore, no significant associations were observed between frontal CBF and gait variables in either the self-paced or dual-task condition. Sensitivity analyses which were restricted to examine the association of velocity and thalamic CBF identified a cofounding effect of depressive symptoms which increased the effect size of the CBF-gait association by 12%. CONCLUSION: Subcortical hypoperfusion, particularly in regions that comprise central input/output tracts to the cortical tissue, may underlie the association between gait deficits and brain aging.

Sex differences in the relationship between dietary pattern adherence and cognitive function among older adults: findings from the NuAge study.

BACKGROUND: Consumption of a prudent dietary pattern rich in healthy nutrients is associated with enhanced cognitive performance in older adulthood, while a Western dietary pattern low in healthy nutrients is associated with poor age-related cognitive function. Sex differences exist in dietary intake among older adults; however, there is a paucity of research examining the relationship between sex-specific dietary patterns and cognitive function in later life. METHODS: The current study aimed to investigate sex differences in the relationship between sex-specific dietary pattern adherence and global cognitive function at baseline and over a 3-year follow-up in 1268 community-dwelling older adults (Mage = 74 years, n = 664 women, n = 612 men) from the Quebec Longitudinal Study on Nutrition and Successful Aging (NuAge). A 78-item Food Frequency Questionnaire was used to estimate dietary intake over the previous year. Sex-specific dietary pattern scores were derived using principal component analysis. Global cognition was assessed using the Modified Mini-Mental State Examination (3MS). RESULTS: Adjusted linear mixed effects models indicated that a healthy, prudent dietary pattern was not associated with baseline cognitive performance in men or women. No relationship was found between Western dietary pattern adherence and baseline cognitive function in women. Among men, adherence to an unhealthy, Western dietary pattern was associated with poorer baseline cognitive function (ß = - 0.652, p = 0.02, 95% CI [- 1.22, - 0.65]). No association was found between prudent or Western dietary patterns and cognitive change over time in men or women. CONCLUSIONS: These findings highlight the importance of conducting sex-based analyses in aging research and suggest that the relationship between dietary pattern adherence and cognitive function in late life may be sex-dependent.

Cardiovascular risk and encoding-related hippocampal connectivity in older adults.

BACKGROUND: Cardiovascular conditions contribute to brain volume loss, reduced cerebrovascular health, and increased dementia risk in aging adults. Altered hippocampal connectivity has also been observed in individuals with cardiovascular conditions, yet the functional consequences of these changes remain unclear. In the present study, we collected functional magnetic resonance imaging data during memory encoding and used a psychophysiological interaction analysis to examine whether cardiovascular burden, indexed using the Framingham risk score, was associated with encoding-related hippocampal connectivity and task performance in cognitively-intact older adults between 65 and 85 years of age. Our goal was to better understand the early functional consequences of vascular and metabolic dysfunction in those at risk for cognitive decline. RESULTS: High Framingham risk scores were associated with lower total brain volumes. In addition, those with high Framingham risk scores showed an altered relationship between left hippocampal-medial prefrontal coupling and task performance compared to those with low Framingham risk scores. Specifically, we found a significant interaction of Framingham risk and learning on connectivity between the left hippocampus and primarily left midline prefrontal regions comprising the left ventral anterior cingulate cortex and medial prefrontal cortex. Those with lower Framingham risk scores showed a pattern of weaker connectivity between left hippocampal and medial prefrontal regions associated with better task performance. Those with higher Framingham risk scores showed the opposite pattern; stronger connectivity was associated with better performance. CONCLUSIONS: Findings from the current study show that amongst older adults with cardiovascular conditions, higher Framingham risk is associated with lower brain volume and altered left hippocampal-medial prefrontal coupling during task performance compared to those with lower Framingham risk scores. This may reflect a compensatory mechanism in support of memory function and suggests that older adults with elevated cardiovascular risk are vulnerable to early Alzheimer disease-like dysfunction within the episodic memory system.

A systematic review of existing peripheral biomarkers of cognitive aging: Is there enough evidence for biomarker proxies in behavioral modification interventions?: An initiative in association with the nutrition, exercise and lifestyle team of the Canadian Consortium on Neurodegeneration in Aging.

Peripheral biomarkers have shown significant value in predicting brain health and may serve as a useful proxy measurement in the assessment of evidence-based lifestyle behavior modification programs, including physical activity and nutrition programs, that aim to maintain cognitive function in late life. The aim of this systematic review was to elucidate which peripheral biomarkers are robustly associated with cognitive function among relatively healthy non-demented older adults. Following the standards for systematic reviews (PICO, PRIMSA), and employing MEDLINE and Scopus search engines, 222 articles were included in the review. Based on the review of biomarker proxies of cognitive health, it is recommended that a comprehensive biomarker panel, or biomarker signature, be developed as a clinical end point for behavior modification trials aimed at enhancing cognitive function in late life. The biomarker signature should take a multisystemic approach, including lipid, immune/inflammatory, and metabolic biomarkers in the biological signature index of cognitive health.

Nutrition as a component of dementia risk reduction strategies.

According to the Alzheimer Society of Canada, within the next generation, Canada will experience a more than doubling of individuals living with dementia and a potentially economically crippling 10-fold increase in costs to Canadians. Up to 50% of cases with dementia can be attributed to seven modifiable, predominantly vascular and/or lifestyle-associated, risk factors. Multi-modal dementia risk reduction strategies, targeting diet, exercise, mental stimulation, and vascular risk monitoring, are likely to be the most successful. Diet-related strategies need to focus on overall diet quality and not on individual foods or nutrients. High-quality diets that are associated with better cognitive function and lower dementia risk with aging are high in vegetables, fruits, nuts, whole grains, and fish and low in red meat, high-fat dairy products, sweets, and highly processed foods. It is the time to embed risk reduction strategies into our public health and healthcare infrastructure to proactively address the challenges posed by population aging.

Brain Function Is Linked to LDL Cholesterol in Older Adults with Cardiovascular Risk.

OBJECTIVES: To determine how cardiovascular risk is associated with working memory task performance and task-related suppression of default-mode network (DMN) activity in cognitively intact older adults. DESIGN: A cross-sectional functional magnetic resonance imaging study of older adults with cardiovascular risk factors. SETTING: Rotman Research Institute, Baycrest Health Sciences. PARTICIPANTS: Thirty older adults with cardiovascular risk factors. MEASUREMENTS: Participants provided health information and a blood sample, and underwent functional magnetic resonance imaging during a working memory task and during a breath-hold task to assess cerebrovascular reactivity. RESULTS: Higher plasma low-density lipoprotein cholesterol (LDL-C) was associated with poorer working memory task performance (P = 0.008) and reduced task-related DMN suppression (P = 0.005). A composite index of cardiovascular risk, the Framingham General Cardiovascular Risk Profile, showed no associations with task performance or task-related DMN suppression. These findings were independent of white matter burden and cerebrovascular reactivity and thus cannot be accounted for by individual differences in neurovascular health. CONCLUSION: These findings suggest a deleterious effect of elevated LDL-C on working memory task performance and task-related DMN suppression in older adults with cardiovascular risk. The relations between the Framingham General Cardiovascular Risk Profile, cognitive task performance, and DMN function require further study.

Vascular risk factor burden correlates with cerebrovascular reactivity but not resting state coactivation in the default mode network.

PURPOSE: White matter hyperintensities (WMH) are prevalent among older adults and are often associated with cognitive decline and increased risk of stroke and dementia. Vascular risk factors (VRFs) are linked to WMH, yet the impact of multiple VRFs on gray matter function is still unclear. The goal of this study was to test for associations between the number of VRFs and cerebrovascular reactivity (CVR) and resting state (RS) coactivation among individuals with WMH. MATERIALS AND METHODS: Twenty-nine participants with suspected WMH were grouped based on the number of VRFs (subgroups: 0, 1, or ≥2). CVR and RS coactivation were measured with blood oxygenation level-dependent (BOLD) imaging on a 3T magnetic resonance imaging (MRI) system during hypercapnia and rest, respectively. Default-mode (DMN), sensory-motor, and medial-visual networks, generated using independent component analysis of RS-BOLD, were selected as networks of interest (NOIs). CVR-BOLD was analyzed using two methods: 1) a model-based approach using CO2 traces, and 2) a dual-regression (DR) approach using NOIs as spatial inputs. Average CVR and RS coactivations within NOIs were compared between VRF subgroups. A secondary analysis investigated the correlation between CVR and RS coactivation. RESULTS: VRF subgroup differences were detected using DR-based CVR in the DMN (F20,2 = 5.17, P = 0.015) but not the model-based CVR nor RS coactivation. DR-based CVR was correlated with RS coactivation in the DMN (r(2) = 0.28, P = 0.006) but not the sensory-motor nor medial-visual NOIs. CONCLUSION: In individuals with WMH, CVR in the DMN was inversely associated with the number of VRFs and correlated with RS coactivation.

Whole-food diet worsened cognitive dysfunction in an Alzheimer's disease mouse model.

Food combinations have been associated with lower incidence of Alzheimer's disease. We hypothesized that a combination whole-food diet containing freeze-dried fish, vegetables, and fruits would improve cognitive function in TgCRND8 mice by modulating brain insulin signaling and neuroinflammation. Cognitive function was assessed by a comprehensive battery of tasks adapted to the Morris water maze. Unexpectedly, a "Diet × Transgene" interaction was observed in which transgenic animals fed the whole-food diet exhibited even worse cognitive function than their transgenic counterparts fed the control diet on tests of spatial memory (p < 0.01) and strategic rule learning (p = 0.034). These behavioral deficits coincided with higher hippocampal gene expression of tumor necrosis factor-α (p = 0.013). There were no differences in cortical amyloid-ß peptide species according to diet. These results indicate that a dietary profile identified from epidemiologic studies exacerbated cognitive dysfunction and neuroinflammation in a mouse model of familial Alzheimer's disease. We suggest that normally adaptive cellular responses to dietary phytochemicals were impaired by amyloid-beta deposition leading to increased oxidative stress, neuroinflammation, and behavioral deficits.

A systematic review of type 2 diabetes mellitus and hypertension in imaging studies of cognitive aging: time to establish new norms.

The rising prevalence of type 2 diabetes (T2DM) and hypertension in older adults, and the deleterious effect of these conditions on cerebrovascular and brain health, is creating a growing discrepancy between the "typical" cognitive aging trajectory and a "healthy" cognitive aging trajectory. These changing health demographics make T2DM and hypertension important topics of study in their own right, and warrant attention from the perspective of cognitive aging neuroimaging research. Specifically, interpretation of individual or group differences in blood oxygenation level dependent magnetic resonance imaging (BOLD MRI) or positron emission tomography (PET H2O(15)) signals as reflective of differences in neural activation underlying a cognitive operation of interest requires assumptions of intact vascular health amongst the study participants. Without adequate screening, inclusion of individuals with T2DM or hypertension in "healthy" samples may introduce unwanted variability and bias to brain and/or cognitive measures, and increase potential for error. We conducted a systematic review of the cognitive aging neuroimaging literature to document the extent to which researchers account for these conditions. Of the 232 studies selected for review, few explicitly excluded individuals with T2DM (9%) or hypertension (13%). A large portion had exclusion criteria that made it difficult to determine whether T2DM or hypertension were excluded (44 and 37%), and many did not mention any selection criteria related to T2DM or hypertension (34 and 22%). Of all the surveyed studies, only 29% acknowledged or addressed the potential influence of intersubject vascular variability on the measured BOLD or PET signals. To reinforce the notion that individuals with T2DM and hypertension should not be overlooked as a potential source of bias, we also provide an overview of metabolic and vascular changes associated with T2DM and hypertension, as they relate to cerebrovascular and brain health.

Combined effects of type 2 diabetes and hypertension associated with cortical thinning and impaired cerebrovascular reactivity relative to hypertension alone in older adults.

OBJECTIVE: Type 2 diabetes mellitus is characterized by metabolic dysregulation in the form of hyperglycemia and insulin resistance and can have a profound impact on brain structure and vasculature. The primary aim of this study was to identify brain regions where the combined effects of type 2 diabetes and hypertension on brain health exceed those of hypertension alone. A secondary objective was to test whether vascular impairment and structural brain measures in this population are associated with cognitive function. RESEARCH DESIGN AND METHODS: We enrolled 18 diabetic participants with hypertension (HTN + T2DM, 7 women, 71.8 ± 5.6 years) and 22 participants with hypertension only (HTN, 12 women, 73.4 ± 6.2 years). Cerebrovascular reactivity (CVR) was assessed using blood oxygenation level dependent (BOLD) MRI during successive breath holds. Gray matter structure was evaluated using cortical thickness (CThk) measures estimated from T1-weighted images. Analyses of cognitive and blood data were also performed. RESULTS: Compared to HTN, HTN + T2DM had decreased CVR and CThk in a spatially overlapping region of the right occipital lobe (P < 0.025); CVR group differences were more expansive and included bilateral occipito-parietal areas (P < 0.025). Whereas CVR showed no significant associations with measures of cognitive function (P > 0.05), CThk in the right lingual gyrus ROI and regions resulting from a vertex-wise analysis (including posterior cingulate, precuneus, superior and middle frontal, and middle and inferior temporal regions (P < 0.025) were associated with executive function. CONCLUSIONS: Individuals with T2DM and HTN showed decreased CVR and CThk compared to age-matched HTN controls. This study identifies brain regions that are impacted by the combined effects of comorbid T2DM and HTN conditions, with new evidence that the corresponding cortical thinning may contribute to cognitive decline.

The effects of an exercise and lifestyle intervention program on cardiovascular, metabolic factors and cognitive performance in middle-aged adults with type II diabetes: a pilot study.

BACKGROUND: Canada is experiencing a rise in type II diabetes mellitus (T2DM), a known risk factor for accelerated cognitive decline and dementia. Within the context of an aging population, this will impose significant individual and societal burden, making the development of prevention programs imperative. OBJECTIVE: This pilot study examines the effects of the Diabetes Exercise and Healthy Lifestyle Service, a 24-week intervention program, on cardiovascular, metabolic regulation and cognitive function in adults with T2DM. METHODS: Seventeen middle-aged participants provided blood samples for biological markers, underwent cognitive testing and a physical stress test pre- and post-intervention. Cognitive performance was evaluated using the California Verbal Learning Test (CVLT), Digit Symbol Substitution Tasl (DSST) and fluency test. RESULTS: Adjusted models reveal participants displayed increased cardiovascular fitness (VO2 peak: Mchange=4.09 mL∙kg∙min(-1) SE=1.4), peak heart rate (Mchange= 9.28 beats⋅min(-1) SE=2.68) and change in heart rate (Mchange=10.71 SE=1.76) in response to the stress test (ps<0.05) following the 24-week intervention. A decrease in body mass index (BMI) (Mchange= -1.03 SE=0.40) and depressive symptomatology (CES-D: Mchange = -3.62 SE=1.44) was also found (ps<0.05). No change was found for lipid and glucose levels. Surprisingly, analyses showed that cognitive performance on the CVLT immediate recall (M= -4.37 SE=2.21), CVTL short-delay recall (M= -1.06 SE=0.55), DSST (Mchange= -3 SE=0.53) and category fluency (Mchange= -1.69 SE=0.78) declined following the intervention (ps<0.05); however, decline on the CVLT was limited to adults with co-morbid T2DM and hypertension. CONCLUSION: Additional research is needed to evaluate the benefit of an exercise and lifestyle program that targets cognitive health in those with T2DM.

Unesterified docosahexaenoic acid is protective in neuroinflammation.

Docosahexaenoic acid (22:6n-3) is the major brain n-3 polyunsaturated fatty acid and it is possible that docosahexaenoic acid is anti-inflammatory in the brain as it is known to be in other tissues. Using a combination of models including the fat-1 transgenic mouse, chronic dietary n-3 polyunsaturated fatty acid modulation in transgenic and wild-type mice, and acute direct brain infusion, we demonstrated that unesterified docosahexaenoic acid attenuates neuroinflammation initiated by intracerebroventricular lipopolysaccharide. Hippocampal neuroinflammation was assessed by gene expression and immunohistochemistry. Furthermore, docosahexaenoic acid protected against lipopolysaccharide-induced neuronal loss. Acute intracerebroventricular infusion of unesterified docosahexaenoic acid or its 12/15-lipoxygenase product and precursor to protectins and resolvins, 17S-hydroperoxy-docosahexaenoic acid, mimics anti-neuroinflammatory aspects of chronically increased unesterified docosahexaenoic acid. LC-MS/MS revealed that neuroprotectin D1 and several other docosahexaenoic acid-derived specialized pro-resolving mediators are present in the hippocampus. Acute intracerebroventricular infusion of 17S-hydroperoxy-docosahexaenoic acid increases hippocampal neuroprotectin D1 levels concomitant to attenuating neuroinflammation. These results show that unesterified docosahexaenoic acid is protective in a lipopolysaccharide-initiated mouse model of acute neuroinflammation, at least in part, via its conversion to specialized pro-resolving mediators; these docosahexaenoic acid stores may provide novel targets for the prevention and treatment(s) of neurological disorders with a neuroinflammatory component. Our study shows that chronically increased brain unesterified DHA levels, but not solely phospholipid DHA levels, attenuate neuroinflammation. Similar attenuations occur with acute increases in brain unesterified DHA or 17S-HpDHA levels, highlighting the importance of an available pool of precursor unesterified DHA for the production of enzymatically derived specialized pro-resolving mediators that are critical in the regulation of neuroinflammation.

Relationship between diet quality and cognition depends on socioeconomic position in healthy older adults.

Both diet quality and socioeconomic position (SEP) have been linked to age-related cognitive changes, but there is little understanding of how the socioeconomic context of dietary intake may shape its cognitive impact. We examined whether equal adherence to "prudent" and "Western" dietary patterns, identified by principal components analysis, was associated with global cognitive function [Modified Mini-Mental State Examination (3MS)] in independently living older adults with different SEPs (aged 68-84 y; n = 1099). The interaction of dietary pattern adherence with household income, educational attainment, occupational prestige, and a composite indicator of SEP combining all 3 was examined in multiple-adjusted mixed models over 3 y of follow-up in participants of the NuAge study (Quebec Longitudinal Study on Nutrition and Successful Aging). Adherence to the prudent pattern (vegetables, fruits, fish, poultry, and lower-fat dairy products) was related to higher 3MS scores at recruitment only in the upper categories of income [parameter estimate (B): 0.56; 95% CI: 0.11, 1.01], education (B: 0.44; 95% CI: 0.080, 0.80), or composite SEP (B: 0.37; 95% CI: 0.045, 0.70). High prudent pattern adherence was associated with less cognitive decline only in those with low composite SEP (B: 0.25; 95% CI: 0.0094, 0.50). Conversely, adherence to the Western pattern (meats, potatoes, processed foods, and higher-fat dairy products) was associated with more cognitive decline (B: -0.23; 95% CI: -0.43, -0.032) only in those with low educational attainment. In summary, among individuals with equivalent diet quality, the magnitude and characteristics of the diet-cognition relationship depended on their socioeconomic circumstances. These results suggest that interventions promoting retention of cognitive function through improved diet quality would provide maximum benefit to those with relatively low SEP.

Vitamin K status and cognitive function in healthy older adults.

Evidence is accumulating that vitamin K could have a role in cognition, especially in aging. Using data from the Québec Longitudinal Study on Nutrition and Successful Aging (NuAge), a cross-sectional analysis was conducted to examine the associations between vitamin K status, measured as serum phylloquinone concentrations, and performance in verbal and non-verbal episodic memory, executive functions, and speed of processing. The sample included 320 men and women aged 70 to 85 years who were free of cognitive impairment. After adjustment for covariates, higher serum phylloquinone concentration (log-transformed) was associated with better verbal episodic memory performances (F = 2.43, p = 0.048); specifically with the scores (Z-transformed) on the second (ß = 0.47; 95% confidence interval [CI] = 0.13-0.82), third (ß = 0.41; 95% CI = 0.06-0.75), and 20-minute delayed (ß = 0.47; 95% CI = 0.12-0.82) free recall trials of the RL/RI-16 Free and Cued Recall Task. No associations were found with non-verbal episodic memory, executive functions, and speed of processing. Our study adds evidence to the possible role of vitamin K in cognition during aging, specifically in the consolidation of the memory trace.

The effects of high- and low-risk environments on cognitive function in rats following 2-vessel occlusion of the carotid arteries: a behavioral study.

In a prospective study of environmental factors affecting cognitive recovery from stroke, adult male rats were reared for 3 months in a high-risk (relatively isolated, low activity, high-fat diet, high-stress) or low-risk (social, healthy diet, low-stress, physically active) environment. They then received cognitive testing to assess various aspects of learning and memory before undergoing 2-vessel occlusion (2VO) of the carotid arteries, or sham surgery. Rats were returned to their respective environments post-operatively. Relative to pre-operative levels, 2VO rats exhibited significant cognitive losses that were consistently greater in the high-risk group than its low-risk counterpart. As well, the high-risk 2VO group was impaired, relative to the low-risk 2VO group on tests of new learning introduced post-operatively. At 3-month follow-up testing, rats that had undergone 2VO surgery exhibited further decline on some tests but recovery on others, with recovery generally slower in the high-risk 2VO group. The high-risk environment also affected rats' pre-operative cognitive performance and, to a lesser extent, their performance following sham surgery. Overall, the study shows that rats experiencing cerebral ischemia are more likely to experience severe cognitive deficits if exposed to a high-risk environment and recover more slowly than ischemic rats in a more favorable environment. The results underscore the importance of lifestyle factors with respect to the impact of stroke on cognition and in assessing prospects for recovery of function.

A single measurement of serum phylloquinone is an adequate indicator of long-term phylloquinone exposure in healthy older adults.

Assessment of long-term phylloquinone exposure is challenging in studies investigating vitamin K in health. Data are equivocal as to whether a single measurement of circulating phylloquinone would be adequate. The primary purpose of the present study was to validate the use of a single measurement of serum phylloquinone as a surrogate for long-term phylloquinone exposure in healthy older adults. Using data from the Québec Longitudinal Study on Nutrition and Successful Aging, the objectives were to: 1) determine the reproducibility of circulating phylloquinone over 2 y (n = 234); 2) calculate how a single measurement would rank or classify individuals and attenuate the regression coefficient between circulating phylloquinone and a health outcome; and 3) investigate the association of a single measurement of serum phylloquinone with long-term phylloquinone intakes assessed over the year prior to the blood draw (n = 228). The variance analysis based on 2 blood samples showed a fair to good reproducibility for serum phylloquinone (intra-class correlation = 0.49). The correlation coefficient between the ranking of individuals based on a single measurement of circulating phylloquinone and the "true" ranking would be 0.70. The multiple regression analysis showed that long-term phylloquinone intake was the strongest predictor of serum phylloquinone (t = 4.94; P < 0.001). The partial correlation coefficient (r = 0.32) was comparable with those reported in studies where blood sampling and diet recording were juxtaposed and/or multiple blood samples were used. The present study provides evidence that the use of a single measurement of circulating phylloquinone is adequate for assessing long-term phylloquinone exposure in healthy older adults.

Near-infrared imaging of the effects of glucose ingestion and regulation on prefrontal activation during dual-task execution in healthy fasting older adults.

RATIONALE: Glucose enhancing effects in older adults have mostly been observed for episodic memory, but have recently been found for attentional control performance. Yet, brain activation patterns underlying these effects are still unknown. OBJECTIVE: The present study examined the acute effects of glucose ingestion on prefrontal brain activation during the execution of a divided attention task in fasting non-diabetic older adults. METHODS: Twenty older adults (60 years and older) took part in the study that included two experimental sessions. After an overnight fast, participants received either a glucose drink (50 g) or a placebo (saccharin) drink, following which they completed a dual-task. During task execution, prefrontal activation was recorded with functional near-infrared spectroscopy (fNIRS). A repeated-measures design was used such that each participant served as his or her own control. The two experimental sessions were counterbalanced among participants and were performed two weeks apart. RESULTS: When participants were in the glucose condition, they showed similar dual-task costs for both tasks, whereas in the placebo condition they prioritized one task over the other, with a significantly larger dual-task cost for the non-prioritized task (p<0.01). Differential brain activation was also observed in right ventral-lateral prefrontal regions for oxygenated hemoglobin and deoxygenated hemoglobin, with more activation apparent in the glucose condition (p<0.05). Furthermore, behavioral and activation data were influenced by individual differences in glucose regulation. CONCLUSIONS: Glucose ingestion appears to momentarily enhance fasting seniors' capacity to coordinate more equally two concurrent tasks and this is reflected in brain activation patterns.