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.

Feasibility and preliminary efficacy of the LEAD trial: a cluster randomized controlled lifestyle intervention to improve hippocampal volume in older adults at-risk for dementia

BACKGROUND

Healthy diet and exercise are associated with reduced risk of dementia in older adults. The impact of diet and exercise interventions on brain health is less consistent, especially with dietary interventions which rely on varying approaches. Our objective was to evaluate the feasibility and preliminary efficacy of a 6-month intervention combining exercise with a novel dietary counseling approach to improve hippocampal volume among older adults at-risk for dementia.

METHODS

Participants with vascular risk factors and subjective cognitive decline or early mild cognitive impairment were cluster randomized in groups of 3-4 to the diet intervention (DIET) or control education (ED) group. All participants engaged in 1 h of supervised exercise per week and additional exercise at home. DIET involved 1 h per week of group-based dietary counseling comprising education, goal setting, and strategy training. ED involved 1 h per week of group-based brain health education classes. Our primary outcome was change in hippocampal volume from baseline to 6 months. Secondary outcomes included changes in cognitive function, blood biomarkers, diet, and fitness. Recruitment challenges and early discontinuation of the trial due to COVID-19 necessitated a revised focus on feasibility and preliminary efficacy.

RESULTS

Of 190 older adults contacted, 14 (7%) were eligible and enrolled, constituting 21% of our recruitment target. All participants completed the intervention and attended 90% of exercise and DIET/ED sessions on average. All 6-month assessments prior to COVID-19 were completed but disruptions to in-person testing resulted in incomplete data collection. No serious adverse events occurred and all participants expressed positive feedback about the study. Preliminary findings did not identify any significant changes in hippocampal volume; however, substantial improvements in diet and HbA1c were observed with DIET compared to ED (d = 1.75 and 1.07, respectively).

CONCLUSIONS

High adherence and retention rates were observed among participants and preliminary findings illustrate improvements in diet quality and HbA1c. These results indicate that a larger trial is feasible if difficulties surrounding recruitment can be mitigated.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03056508 .

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.

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.

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 (M_age = 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 (β = - 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.

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.

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.

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.

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.

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.

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 (β = 0.47; 95% confidence interval [CI] = 0.13-0.82), third (β = 0.41; 95% CI = 0.06-0.75), and 20-minute delayed (β = 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.

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.

Glucose regulation is associated with attentional control performances in nondiabetic older adults

Less efficient glucose regulation, the ability to metabolize glucose, has been associated with poorer cognitive performances in older individuals not meeting criteria for type 2 diabetes ( Messier, Tsiakas, Gagnon, & Desrochers, 2010 ). Yet, the influence of glucose regulation on attentional functions, which are sensitive to aging, is still unclear. The present study examined the relationship between glucose regulation and performances on attentional tasks in nondiabetic older adults. Twenty-two participants (60 years and older) were tested on neuropsychological tests of attention (Trail Making test, modified Stroop test) and on a computerized dual task, after receiving a 50-g glucose drink. Participants with the worse glucose regulation committed more errors on the switching condition of the modified Stroop test (p < .05) and tended to make more errors in divided-attention trials of the computerized dual task (p = .05). Altogether, these results suggest that glucose regulation may transiently influence performances of metabolically healthy older adults on tasks requiring switching attention.

A minimum of six days of diet recording is needed to assess usual vitamin K intake among older adults

There is a growing interest in the role of vitamin K in health, especially in aging populations. Knowledge of inter- and intra-individual variability of dietary vitamin K intake could be useful to accurately assess usual intake and rank participants in epidemiological studies. Our objectives were to: 1) estimate the variance components of vitamin K intake; 2) investigate whether day of the week, season, and energy intake are factors related to intra-individual variance; and 3) calculate the requisite number of days to achieve desired degrees of accuracy for estimating individual vitamin K intake, ranking individuals and estimating regression coefficient. Vitamin K intake was assessed in 939 older adults (67-84 y) enrolled in the Québec Longitudinal Study on Nutrition and Successful Aging study using 2 sets of 3 nonconsecutive multiple-pass 24-h dietary recalls (24HR) collected 6 mo apart. Each set included 2 weekdays and one weekend day. Intra- to inter-individual variance ratios for vitamin K intake were 3.2 (95% CI = 2.6-3.9) overall, 2.6 (95% CI = 2.1-3.5) for men, and 3.7 (95% CI = 2.9-5.0) for women. Day of the week (weekdays) and season (May to October) were positively and significantly associated with vitamin K intake but explained a negligible part of intra-individual variation (<1%). Adjusting for energy intake explained <7% of variance and did not affect the variance ratio. Six to 13 24HR are required to properly rank individuals according to their usual vitamin K intake and limit attenuation of the regression coefficient. These results should be considered in studies planning to assess vitamin K intakes in older adults.

The TNF-alpha-238G > a single-nucleotide polymorphism protects against memory decline in older adults with type 2 diabetes

Inflammatory markers predict memory dysfunction in elderly patients, but their contribution to memory deficits in adults with Type 2 diabetes mellitus (T2DM) is less well understood. The present study determined whether specific single-nucleotide polymorphisms in the promoter region of tumor necrosis factor-alpha (TNF-alpha) predict verbal memory in older patients with T2DM. Immediate and delayed verbal memory were assessed using word list and paragraph recall tests in a cohort of subjects with T2DM during 2 sessions, separated by 48 weeks. The presence of the TNF-alpha-238A allele, which has been shown to decrease gene expression, consistently predicted better baseline performance and protected against memory decline over a period of 48 weeks. Therefore, inflammatory mediators may be important modulators of memory function in individuals with T2DM.

Changes in type of foodservice and dining room environment preferentially benefit institutionalized seniors with low body mass indexes

OBJECTIVE

To compare energy intakes in seniors with cognitive impairment residing in long-term care and receiving meals by bulk (cafeteria style with waitress service) vs traditional tray delivery systems and determine subject characteristics that identify responsiveness to type of foodservice provided. DESIGN AND SUBJECTS/SETTING: Usual energy intakes were compared in subjects residing in cognitive impairment units in either the old (tray delivery, n=23) or new (bulk delivery, n=26) nursing home at Baycrest, a teaching facility associated with University of Toronto Medical School.

INTERVENTION

Changes to foodservice and physical environment (from institutional to more home-like environment).

MAIN OUTCOME MEASURES

Twenty-one consecutive day investigator-weighed energy and macronutrient intakes and behavioral function (London Psychogeriatric Rating Scale).

STATISTICAL ANALYSES PERFORMED

Analysis of variance determined mean differences in intake and regression analyses identified predictors of sensitivity to type of food delivery systems.

RESULTS

Higher 24-hour total (P<0.001) and dinner (P<0.001) energy intakes in subjects receiving bulk compared to tray delivery were predominantly associated with greater carbohydrate intakes (P<0.001). Higher energy, carbohydrate, and protein, but not fat intakes, with bulk delivery were more apparent in individuals with lower body mass indexes (BMIs) (food delivery by BMI interaction, all P values <0.05).

CONCLUSIONS

High-risk, cognitively impaired individuals with low BMI benefited the most from the changed foodservice and physical environment, whereas individuals with higher BMIs did not show substantive changes in intake. Bulk foodservice and a home-like dining environment optimize energy intake in individuals at high risk for malnutrition, particularly those with low BMIs and cognitive impairment.

Energy-containing nutritional supplements can affect usual energy intake postsupplementation in institutionalized seniors with probable Alzheimer's disease

OBJECTIVES

To determine whether increases in caloric intake associated with consumption of a mid-morning nutritional supplement for 3 weeks were maintained in the week after stopping the supplement and to investigate the effects of body mass index (BMI) and cognitive and behavioral measures on this response.

DESIGN

Secondary analysis of a previously published randomized, crossover, nonblinded clinical trial.

SETTING

A fully accredited geriatric care facility affiliated with the University of Toronto.

PARTICIPANTS

Thirty institutionalized seniors with probable Alzheimer's disease (AD) who ate independently.

MEASUREMENTS

Investigator-weighed food intake, body weight, cognitive (Severe Impairment Battery; Global Deterioration Scale) and behavioral (Neuropsychiatric Inventory--Nursing Home version; London Psychogeriatric Rating Scale) assessments.

RESULTS

Individuals who responded successfully to supplementation as indicated by increases in daily energy intake were likely to maintain 58.8% of that increase postsupplementation, although stopping the supplement was associated with decreased habitual energy intake in low-BMI individuals who reduced their daily intakes during supplementation in response to the extra calories. Cognitive/behavioral tests were not reliable predictors of postsupplement intake.

CONCLUSION

Institutionalized seniors with probable AD are likely to alter their usual energy intakes to maintain changes resulting from 3 weeks of supplementation. This effect may allow for rotating supplementation schedules in nursing homes that could reduce staff burden, but only for those individuals who are most likely to respond favorably. These data indicate that nutritional supplements and diet plans should be carefully prescribed in low-BMI individuals to limit variability in total energy provided and thus prevent lower-than-normal intake.

Better cognitive performance following a low-glycaemic-index compared with a high-glycaemic-index carbohydrate meal in adults with type 2 diabetes

AIMS/HYPOTHESIS

Transient hyperglycaemia, consistent with that observed with normal meal ingestion, may be detrimental to cognitive performance in adults with type 2 diabetes. This study determined whether minimising the postprandial increase in blood glucose through the ingestion of low- rather than high-glycaemic-index (GI) carbohydrate meals differentially affected cognitive performance in the postprandial period.

SUBJECTS AND METHODS

Using a within-individual design, 21 free-living subjects (65+/-7.29 years) with type 2 diabetes consumed 50 g carbohydrate as a meal with either a low GI (pasta) or a high GI (white bread), or water on three separate mornings following an overnight fast. Neuropsychological tests were administered and plasma glucose concentrations measured.

RESULTS

Higher postprandial blood glucose AUC (gAUC) was associated with poorer verbal memory (paragraph recall, p=0.01; word list recall, p=0.012). Both the GI of the carbohydrate meal and individual differences in response to meal ingestion contributed to the variation in gAUC and consequent memory recall. Bread consumption, relative to pasta, resulted in both a higher gAUC (p<0.05) and worse delayed verbal memory performance (paragraph recall, p=0.042; wordlist recall, p=0.035). Additionally, performance following bread consumption was poorer than that following pasta on measures of working memory, executive function and auditory selective attention, while sustained attention showed no sensitivity to type of carbohydrate food consumed.

CONCLUSIONS/INTERPRETATION

Consuming 50 g of a low-GI carbohydrate meal, relative to a high-GI carbohydrate meal, generally results in better cognitive performance in the postprandial period in adults with type 2 diabetes, particularly in those individuals who experience the greatest food-induced elevations in blood glucose levels.

Memory impairment in obese Zucker rats: an investigation of cognitive function in an animal model of insulin resistance and obesity

The genetically obese Zucker rat is a widely investigated model of pathological changes associated with type 2 diabetes. To assess cognitive function, obese and lean Zucker rats were tested on a variable-interval delayed alternation test of learning and memory. There were no group differences in learning the alternation rule or at short intervals, but obese rats were impaired at longer intervals where performance is hippocampus dependent. Plasma membrane association of the insulin sensitive glucose transporter, GLUT4, was reduced in the hippocampus of obese rats in the absence of changes in total GLUT4 and insulin receptor expression. These results parallel those of human studies in pointing to the susceptibility of the hippocampus and related structures to the adverse environment of diabetes mellitus.

High-fat diets, insulin resistance and declining cognitive function

Results from our work in rats and others findings from human epidemiologic studies demonstrate deficits in cognitive performance following chronic ingestion of high fat, high saturated fat, diets. Yet, the precise physiologic mechanism underlying these deficits is not well understood. We report that older adults with insulin resistance show remarkably similar deficits in cognitive function and respond to glucose ingestion in a comparable manner to rodents fed a high-fat diet, suggesting that insulin resistance is a probable mediator of these diet-induced deficits. As insulin resistance worsens to overt type 2 diabetes, profound deficits in cognitive functions, especially those dependent on the medial temporal lobes, are apparent in both obese Zucker rats and humans with type 2 diabetes. Unlike the older adult with insulin resistance, glucose ingestion further impairs medial temporal lobe function in adults with type 2 diabetes. Collectively, the human and rodent data point to a role of diet-induced endocrine abnormalities, including the development of insulin resistance, as mediating the cognitive deficits associated with high fat consumption.

A randomized, crossover trial of high-carbohydrate foods in nursing home residents with Alzheimer's disease: associations among intervention response, body mass index, and behavioral and cognitive function

BACKGROUND

Despite recognition that weight loss is a problem in elderly persons with probable Alzheimer's disease (AD), increasing their food intake remains a challenge. To effectively enhance intake, interventions must work with individuals' changing needs and intake patterns. Previously, the authors reported greater food consumption at breakfast, a high-carbohydrate meal, compared with dinner, and shifts toward carbohydrate preference at dinner in those with increased behavioral difficulties, low body mass index, or both.

METHODS

Thirty-four nursing home residents with probable AD who ate independently participated in a randomized, crossover, nonblinded study of two nutrition interventions. The intervention described here included replacing 12 nonconsecutive "traditional" dinners with meals high in carbohydrate but comparable to traditional dinners in protein. Measures included weighed food intake, body weight, cognitive function (as assessed using the Severe Impairment Battery and Global Deterioration Scale), behavioral disturbances (as assessed using the Neuropsychiatric Inventory-Nursing Home Version), and behavioral function (as assessed using the London Psychogeriatric Rating Scale).

RESULTS

Group mean dinner and 24-hour energy intake increased during the intervention phase compared with baseline, protein intake was unaffected, and carbohydrate intake increased. Increased dinner intake, attributable to intervention foods, was achieved in 20 of 32 of participants who completed the study and was associated with increased carbohydrate preference, poorer memory, and increased aberrant motor behavior. Those with low body mass indices were the most resistant to the intervention.

CONCLUSIONS

Providing a high-carbohydrate meal for dinner increases food intake in seniors at later stages of the disease who are experiencing cognitive and behavioral difficulties, possibly as a result of a shift in preference for high-carbohydrate foods.

Studies of the effects of high fat diets on cognitive function in a rat model

This research summarises a research program that is concerned with the effects of high fat diets on cognitive function in rats. The diets selected accurately represent current upper limits of human fat consumption in western societies. Rats fed with diets high in saturated or unsaturated fat for 3 months, were severely impaired on a range of learning and memory tasks. Related studies showed that these effects were modulated by concentration of fat, environmental influences, and treatment with glucose. More work is needed to identify the neurobiological mechanisms underlying this impairment but saturated fatty acid intake, as well as insulin resistance and glucose intolerance may be important factors. In demonstrating a clear relationship between obesity and cognitive impairment, this research has important implications for aging. Older adults are particularly vulnerable to the adverse effects of dietary fat and the present results underscore the importance of evidence that seniors with marginal levels of nutrient intake often perform poorly on tests of cognitive function, and are at increased risk for various forms of dementia.

Behavioral Disturbances, Not Cognitive Deterioration, Are Associated With Altered Food Selection in Seniors With Alzheimer's Disease

OBJECTIVE

We previously reported alterations in circadian patterns of food intake that are associated with measures of functional and cognitive deterioration in seniors with probable Alzheimer's disease (AD). This study further explored disturbed eating patterns in AD, focusing on alterations in macronutrient (protein, carbohydrate, and fat) selection, and their association with measures of functional and behavioral losses.

METHODS

Forty-nine days of food intake collections were conducted on 32 residents (26 females, 6 males; age = 88.4 +/- 4.1 years; body mass index = 24.1 +/- 4.0 kg/m(2)) with probable AD residing at a nursing home (a fully accredited geriatric teaching facility affiliated with the University of Toronto's Medical School). All residents ate their meals independently. The relationships between patterns of habitual food consumption and measures of cognitive function (Severe Impairment Battery), behavioral disturbances (Neuropsychiatric Inventory-Nursing Home Version) and behavioral function (London Psychogeriatric Rating Scale) were examined, cross-sectionally.

RESULTS

Consistent with our previous studies, breakfast intakes were not predicted by any of the measures of behavioral, cognitive, or functional deterioration, although those residents with greater functional deterioration, especially disengagement, attained lower 24-hour energy intakes. The presence of "psychomotor disturbances," including irritability, agitation, and disinhibition, were strongly associated with shifts in eating patterns toward carbohydrate and away from protein, placing individuals with these conditions at increased risk for inadequate protein intakes. Between-individual differences in intake patterns could not be explained by the use of either anorexic or orexigenic medications.

CONCLUSIONS

Behavioral, not cognitive, deterioration is associated with appetite modifications that increase risk of poor protein intake, perhaps indicating a common monoaminergic involvement.

Nutrients as trophic factors in neurons and the central nervous system: role of retinoic acid

In multicellular organisms, death, survival, proliferation, and differentiation of a given cell depend on signals produced by neighboring and/or distant cells, resulting in the coordinated development and function of the various tissues. In the nervous system, control of cell survival and differentiation is achieved through the action of a distinct group of polypeptides collectively known as neurotrophic factors. Recent findings support the view that trophic factors also are involved in the response of the nervous system to acute injury. By contrast, nutrients are not traditionally viewed as potential trophic factors; however, there is increasing evidence that at least some influence neuronal differentiation. During development the brain is responsive to variations in nutrient supply, and this increased sensitivity or vulnerability of the brain to nutrient supply may reappear during neuronal repair, a period during which a rapid membrane resynthesis and reestablishment of synthetic pathways occur. To further evaluate the potential of specific nutrients to act as pharmacologic agents in the repair of injured neurons, the effects of retinoic acid, an active metabolite of vitamin A, and its role as a trophic factor are discussed. This literature review is intended to provide background information regarding the effect of retinoic acid on the cholinergic phenotype and the differentiation of these neurons and to explain how it may promote neuronal repair and survival following injury.

Providing nutrition supplements to institutionalized seniors with probable Alzheimer's disease is least beneficial to those with low body weight status

OBJECTIVES

To examine whether providing a midmorning nutrition supplement increases habitual energy intake in seniors with probable Alzheimer's disease (AD) and to investigate the effects of body weight status and cognitive and behavioral function on the response to the intervention.

DESIGN

Randomized, crossover, nonblinded clinical trial.

SETTING

A fully accredited geriatric teaching facility affiliated with the University of Toronto's Medical School with a home for the aged.

PARTICIPANTS

Thirty-four institutionalized seniors with probable AD who ate independently.

INTERVENTION

Nutrition supplements were provided between breakfast and lunch for 21 consecutive days and compared with 21 consecutive days of habitual intake.

MEASUREMENTS

Investigator-weighed food intake, body weight, cognitive function (Severe Impairment Battery and Global Deterioration Scale), behavioral disturbances (Neuropsychiatric Inventory-Nursing Home Version), and behavioral function (London Psychogeriatric Rating Scale).

RESULTS

Relative to habitual intake, group mean analyses showed increased 24-hour energy, protein, and carbohydrate intake during the supplement phase, but five of 31 subjects who finished all study phases completely compensated for the energy provided by the supplement by reducing lunch intake, and 24-hour energy intake was enhanced in only 21 of 31 subjects. Compensation at lunch was more likely in subjects with lower body mass indices, increased aberrant motor behavior, poorer attention, and increased mental disorganization/confusion.

CONCLUSION

Nutrition supplements were least likely to enhance habitual energy intake in subjects who would normally be targeted for nutrition intervention-those with low body weight status. Those likely to benefit include those with higher body mass indices, less aberrant motor problems, less mental disorganization, and increased attention.

Carbohydrate-induced memory impairment in adults with type 2 diabetes

OBJECTIVE

Memory impairment is observed in adults with type 2 diabetes. The focus of this study was to determine whether acute carbohydrate consumption contributes to or exacerbates memory dysfunction.

RESEARCH DESIGN AND METHODS

The impact of consuming 50 g of rapidly absorbed carbohydrate (one half bagel and white grape juice) at breakfast was examined in 19 adults with type 2 diabetes. Subjects (mean age 63 +/- 9 years, mean BMI 26.1 +/- 4.5 kg/m(2)) were tested, under fed and fasted conditions, on verbal declarative memory using both word list and paragraph recall tests (immediate and delayed [7-min] recall), Trails Test Part B as a measure of general brain function, and mood (subjectively monitoring global vigor and affect).

RESULTS

Under baseline (fasting) conditions, elevated blood HbA(1c) was negatively associated with immediate and delayed paragraph recall performance (R(2) = 0.30; P = 0.024) and higher fasting blood glucose trended toward poorer word list recall (R(2) = 0.09; P = 0.102). Carbohydrate ingestion influenced measures of delayed, but not immediate, recall in a time-dependent fashion (time x food) (word list, P = 0.046; paragraph, P = 0.044) such that delayed recall was improved at 15 min postingestion but was impaired at 30 min. Neither Trails Test scores (P = 0.17) nor mood (affect, P = 0.68 and vigor, P = 0.45) were influenced by food ingestion.

CONCLUSIONS

In adults with type 2 diabetes, poorer glycemic control is associated with lower performance on tests of declarative memory. Acute ingestion of high glycemic index carbohydrate foods further contributes to the underlying memory impairment.

Dietary carbohydrate, glucose regulation, and cognitive performance in elderly persons

Chronic intake patterns during the adult years and the acute ingestion of meals or foods influence cognitive performance in seniors. Many chronic diseases, including type 2 diabetes mellitus, cardiovascular disease, and hypertension, which are risk factors for cognitive impairment and/or dementia, share the same dietary risk factors as those for cognitive impairment. Conversely, acute macronutrient and/or food consumption improves performance on cognitive tasks. While consumption of all macronutrients enhances cognitive performance, the benefits of carbohydrate intake appear more sustained in comparison to fat and protein.

Malnutrition in institutionalized seniors: the iatrogenic component

OBJECTIVES

To provide practitioners with benchmarks for micronutrient supplementation policies for older residents of long-term care (LTC) facilities, based upon residents' usual energy intake.

DESIGN

Retrospective secondary analysis of nutrient intake and delivery data, obtained from 21 consecutive collection days.

SETTING

A fully accredited geriatric teaching facility, affiliated with the University of Toronto's Medical School, that includes a chronic care hospital and a home for the aged, housing more than 800 senior residents.

PARTICIPANTS

Twenty-three cognitively impaired residents who retained the ability to feed themselves.

MEASUREMENTS

Average daily micronutrient (vitamin and mineral) content of two common diet types--unrestricted diet as tolerated and lactose-free--were evaluated based upon all foods served during a 28-day cycle of menus, providing an estimate of total possible micronutrient intake. Energy intake needed to meet recommended intakes for each of the micronutrients was then determined and compared with actual dietary intakes.

RESULTS

Even if entirely consumed, neither diet (providing approximately 2,000 kcal/d) supplied sufficient quantities of vitamins (vitamin E, pantothenic acid) and minerals (calcium, zinc, copper and manganese) to enable residents to meet recommended intakes, making these deficiencies iatrogenic in nature. As projected intake levels fell to reflect ranges more consistently observed in LTC residents (1,000-1,500 kcal/d), the number and severity of risk nutrients increased. Similar predictions, based upon actual intake measurements, were made and confirmed.

CONCLUSIONS

The traditional approach of developing LTC menus using resources such as Canada's Food Guide or the Food Guide Pyramid of the United States results in iatrogenic malnutrition. New guidelines are needed that are targeted toward the special needs of older adults who have low food intakes. In the interim, all older LTC residents require full-spectrum vitamin and mineral supplements.

Influence of dietary carbohydrates and glycaemic response on subjective appetite and food intake in healthy elderly persons

Increased satiety and decreased food intake are reported following the consumption of low glycaemic index (GI) foods, which gradually increase blood glucose. This observation, however, is not uniformly supported and few studies have examined the impact of different GI foods on satiety and intake in the elderly. After an overnight fast, 10 men and 10 women (aged 60-82 years) consumed similar amounts of available carbohydrate as high (glucose drink or potatoes) or low (barley) GI foods or a non-energy placebo drink on four mornings. Blood glucose and subjective appetite were measured throughout a 120 min post-ingestion period, followed by consumption of an ad libitum lunch. Differences in plasma glucose after test food ingestion (glucose > potatoes > barley > placebo; P < 0.03) did not predict subjective appetite or lunch intake. Potatoes increased subjective satiety the most, followed by barley, then glucose, which trended towards greater satiety than placebo. Potatoes led to less hunger than placebo (P = 0.0023) and less prospective consumption than the other three foods (P < 0.0083), and potatoes and barley led to greater fullness than glucose and placebo (P < 0.0001). Lunch intake was decreased, compared with placebo (502 +/- 47 kcal, P < 0.031), by potatoes (405 +/- 40 kcal) and barley (441 +/- 41 kcal); however, only potatoes (41.9 +/- 12.3%) led to greater compensation at lunch for test food ingestion compared with glucose (11.9 +/- 9.5%, P = 0.016). These results suggest that elderly subjects are sensitive to the effects of different foods on subjective appetite and food intake, and that the GI of the foods tested did not predict their effects on satiety and food intake.

Shift in diurnal feeding patterns in nursing home residents with Alzheimer's disease

BACKGROUND

Individuals with Alzheimer's disease (AD) are highly susceptible to weight loss and malnutrition, which, to date, have not been associated with decreased food consumption. The current study examined food intake patterns and how they change in relation to body mass index (BMI), behavioral function, and cognitive status in institutionalized seniors with AD.

METHODS

Twenty-one consecutive days of investigator-weighed food intake collections were conducted on 25 subjects with likely AD residing at a home for the aged. All subjects maintained the ability to self-feed.

RESULTS

Eighty-eight percent of participants did not meet targeted energy needs, including an estimated 37% prevalence of protein inadequacy. Subjects with increased behavioral difficulties, based on the London Psychogeriatric Rating Scale, had reduced meal-related intakes that were highly associated with decreased energy consumption at dinner. With behavioral changes, particularly increased mental disorganization and confusion, there was a shift in circadian eating patterns such that the greatest proportion of daily energy was consumed at breakfast. Individuals with low BMIs tended to be those with more behavioral difficulties, such that BMI was also associated with the shift in overall eating patterns.

CONCLUSIONS

Changes in behavioral function in seniors with AD result in a circadian shift in intake patterns with the preponderance of calories consumed at breakfast in those with increased behavioral difficulties. This shift in eating patterns associates both with poor overall intake and poor BMI.

Dietary protein, carbohydrate, and fat enhance memory performance in the healthy elderly

BACKGROUND

Dietary carbohydrates can improve memory. Whether these effects are related to elevations in blood glucose or to energy ingestion is unknown.

OBJECTIVES

Our objectives were to determine 1) the influence of isoenergetic protein-, carbohydrate-, and fat-containing drinks on cognitive performance and 2) whether the time period after ingestion affects cognition.

DESIGN

After fasting overnight, 11 men and 11 women aged 61-79 y consumed either a 300-mL drink containing 774 kJ as pure protein (whey), carbohydrate (glucose), or fat (safflower oil) or a nonenergy placebo on 4 separate mornings. Cognitive tests were administered 15 and 60 min after ingestion of the drinks. Plasma glucose and serum insulin concentrations were measured.

RESULTS

Only the carbohydrate drink increased blood glucose (P < 0.0001). Compared with the placebo, all 3 macronutrients improved delayed paragraph recall (PR) (P < 0.001) and improved or tended to improve immediate PR (P < 0.04) 15 min after ingestion. Beneficial effects on other cognitive tests were confined to one or more of the macronutrients: carbohydrate improved Trail Making Test (Trails) performance at 60 min (P = 0.02) and tended to improve Trails at 15 min (P = 0.04) and PR at 60 min in men, carbohydrate and fat improved or tended to improve performance on Trails at 15 and 60 min in subjects with poor baseline scores (r > -0.41, P < 0.03), fat tended to improve attention at 60 min (P < 0.05), and protein reduced the rate of forgetting on the PR at 15 min (P = 0.002).

CONCLUSIONS

Energy intake from protein, carbohydrate, or fat can enhance memory independently of elevations in blood glucose. Each macronutrient may also exert unique effects on cognition.

Meal delivery practices do not meet needs of Alzheimer patients with increased cognitive and behavioral difficulties in a long-term care facility

BACKGROUND

Alterations in circadian rhythms and behavioral difficulties likely impact meal consumption patterns in elderly individuals with probable Alzheimer's disease (AD). Despite these known changes, the profile of meals provided in the institution parallels the needs of younger, free-living, healthy populations. This investigation examined the impact of food delivery patterns on achieved intakes in elderly individuals with probable AD in a long-term care facility and how this relationship changes depending on time of day, body weight status, behavioral function, and cognitive ability.

METHODS

Twenty-one consecutive days of investigator-weighed food intake and delivery collections were conducted on 25 elderly individuals with probable AD who maintained the ability to self-feed.

RESULTS

Energy consumed was positively associated with energy delivered for the majority of subjects, although the strength of this relationship varied across subjects and throughout the day. Energy delivered had the greatest impact on energy consumed at breakfast and the least impact at dinner in those with the greatest behavioral difficulties and cognitive impairment. Although those with low body mass indexes (BMIs) were likely to be delivered more energy, the impact of delivery on intakes decreased as energy delivered increased.

CONCLUSIONS

Delivering excess energy to patients with poor BMIs likely does not result in increased energy consumption. Behavioral and cognitive deterioration leads to a shift in the time of day that energy delivered has an impact on energy consumption, with the most progressed individuals being most impacted by foods delivered in the morning, suggesting that traditional meal practices are inappropriate for elderly individuals with AD.

Glucose treatment reduces memory deficits in young adult rats fed high-fat diets

Feeding rats high-fat diets for 3 months produces a widespread cognitive deficit that affects performance on a wide range of learning and memory tasks. The present study tested the hypothesis that this effect is related to a fat-induced impairment in glucose metabolism. Following 3 months of dietary intervention (20% by weight fat diets, composed primarily of either beef tallow or soybean oil versus standard laboratory chow), male Long-Evans rats were tested on a variable interval delayed alternation (VIDA) task that measures learning and memory functions that differentially involve specific brain regions. Relative to rats fed chow, rats consuming the high-fat diets were impaired on all aspects of VIDA performance. Following baseline testing, rats were maintained on their respective diets and the effect of glucose administration (100 mg/kg BW; i.p.) was examined. For the next 6 days, animals alternately received injections of saline or glucose 30 min prior to VIDA testing. Glucose treatment improved performance, with the effect being most pronounced at the longer intertrial intervals where task performance is sensitive to hippocampal impairment. Importantly, the beneficial effect of glucose were confined to those animals consuming the high-fat diets and were not observed in rats fed chow. These results demonstrate that glucose administration can overcome those deficits associated with hippocampal function in rats fed high-fat diets and are consistent with the hypothesis that high-fat diets, in part, mediate their effect through the development of insulin resistance and glucose intolerance.

Cognitive performance is associated with glucose regulation in healthy elderly persons and can be enhanced with glucose and dietary carbohydrates

BACKGROUND

A glucose drink has been shown to improve memory in persons with poor glucose regulation and poor cognition.

OBJECTIVE

The objective of this study was to determine 1) whether an association between cognition and glucose regulation is apparent in healthy seniors and 2) the effects of dietary carbohydrates on cognition.

DESIGN

After an overnight fast, 10 men and 10 women (aged 60-82 y) consumed 50 g carbohydrate as glucose, potatoes, or barley or a placebo on 4 separate mornings. Cognitive tests were administered 15, 60, and 105 min after ingestion of the carbohydrate. Plasma glucose and serum insulin were measured.

RESULTS

In a multiple regression analysis, poor baseline (placebo) verbal declarative memory (immediate and 20-min delayed paragraph recall and word list recall) and visuomotor task performance were predicted by poor beta cell function, high incremental area under the glucose curve, low insulin resistance, and low body mass index. The difference in plasma glucose after food consumption [glucose > potatoes > barley > placebo (P: < 0.03)] did not predict performance. Although overall performance did not differ with consumption of the different test foods, baseline score and beta cell function correlated with improvements in immediate and delayed paragraph recall for all 3 carbohydrates (compared with placebo); the poorer the baseline memory or beta cell function, the greater the improvement (correlation between beta cell function and improvement in delayed paragraph recall: r > -0.50, P: < 0.03). Poor beta cell function correlated with improvement for all carbohydrates in visuomotor task performance but not on an attention task.

CONCLUSIONS

Glucose regulation was associated with cognitive performance in elderly subjects with normal glucose tolerance. Dietary carbohydrates (potatoes and barley) enhanced cognition in subjects with poor memories or beta cell function independently of plasma glucose.

Cholinergic differentiation triggered by blocking cell proliferation and treatment with all-trans-retinoic acid

This study determined whether the effect of all-trans-retinoic acid (t-RA) on markers of cholinergic differentiation in a murine septal cell line, SN56.B5.G4, differed depending upon the cell's proliferative status. To develop a model of non-proliferating cells, aphidicolin, a DNA alpha-polymerase inhibitor, was used. Cessation of proliferation by aphidicolin increased intracellular choline and acetylcholine (ACh) levels in the absence of change to choline acetyltransferase (ChAT) activity and mRNA and vesicular ACh transporter (VAChT) mRNA. Importantly, the response to t-RA differed depending upon proliferative status. Consistent with previous reports, t-RA increased ChAT and VAChT mRNA, ChAT activity and intracellular ACh levels in proliferating SN56 cells with no effect on intracellular choline levels. When cells were treated with t-RA while undergoing proliferative arrest, an additive effect of combined treatment was observed on ACh levels; nevertheless, this was only accompanied by an increase in choline levels, VAChT and ChAT mRNAs, but not ChAT activity. Indeed, aphidicolin treatment completely suppressed the t-RA-induced increase in ChAT activity observed in proliferating cells. To explore the response to t-RA in post-mitotic cells, a sequential treatment of aphidicolin and t-RA was employed. t-RA treatment was ineffective in increasing ACh and choline levels, over and above that observed with the aphidicolin treatment alone. Comparable to the combined treatment, sequential treatment lead to an increase in ChAT mRNA without any increase in ChAT activity. In conclusion, both the magnitude and the mechanism(s) of action whereby t-RA enhances the cholinergic phenotype of SN56 cells is dependent upon the cell's proliferative status.

Nutrient contribution of infant cereals used as fluid thickening agents in diets fed to the elderly

OBJECTIVE

To evaluate whether a nutrient-fortified fluid-thickening agent (Pablum, H. J. Heinz Co of Canada, North York, Ontario, Canada) replaces nutrients lost to food displacement associated with its use.

DESIGN

Seven-day, investigator-weighted, food intake records were evaluated to determine the prevalence of nutrient inadequacy. Nutrient intakes, including and excluding those associated with Pablum, were assessed to determine the ability of Pablum to protect from nutrient inadequacy. SUBJECTS/SETTING SUBJECTS: (19 women and 2 men aged 69 to 109 years) were residents of a home for the aged or a chronic-care hospital who required pureed food and thickened fluids.

STATISTICAL ANALYSES PERFORMED

Probability analysis was used to estimate the prevalence of nutrient inadequacy for micronutrients and protein.

RESULTS

Approximately 15% of consumed energy (mean +/- standard deviation: 1.534 +/- 310 kcal/day; 1.38 +/- 0.37 and 1.46 +/- 0.26 multiplied by basal metabolic rate for men and women) came from the thickener. If a nonfortified thickener was used, risk of inadequacy (percentage of sample) would be apparent for protein (16%), calcium (95%), thiamin (57%), riboflavin (28%), niacin (55%), and folate (47% for women and 97% for men); no risk was estimated for iron and vitamins A and C. The nutrients contained in Pablum reduced or eliminated the risk of inadequacy for some nutrients, including protein (8%), calcium (9%), thiamin (0%), riboflavin (0%), and niacin (0%). In contrast, inadequate consumption of water and folate occurred even when the contribution of Pablum was considered.

APPLICATIONS

The use of a nutrient-fortified thickening agent has merit; however, the current formulation of Pablum does not allow for complete protection against nutrient inadequacy.