Catherine Mewborn

Lutein and Zeaxanthin Influence Brain Function in Older Adults: A Randomized Controlled Trial

OBJECTIVES The present study constitutes the first randomized controlled trial to investigate the relation of lutein (L) and zeaxanthin (Z) to brain function using functional magnetic resonance imaging (fMRI). It was hypothesized that L and Z supplementation in older adults would enhance neural efficiency (i.e., reduce activation) and cognitive performance on a verbal learning task relative to placebo. METHODS A total of 44 community-dwelling older adults (mean age=72 years) were randomly assigned to receive either placebo or L+Z supplementation (12 mg/daily) for 1 year. Neurocognitive performance was assessed at baseline and post-intervention on an fMRI-adapted task involving learning and recalling word pairs. Imaging contrasts of blood-oxygen-level-dependent (BOLD) signal were created by subtracting active control trials from learning and recall trials. A flexible factorial model was employed to investigate the expected group (placebo vs. supplement) by time (baseline vs. post-intervention) interaction in pre-specified regions-of-interest. RESULTS L and Z appeared to buffer cognitive decline on the verbal learning task (Cohens d=.84). Significant interactions during learning were observed in left dorsolateral prefrontal cortex and anterior cingulate cortex (p < .05, family-wise-error corrected). However, these effects were in the direction of increased rather than decreased BOLD signal. Although the omnibus interaction was not significant during recall, within-group contrasts revealed significant increases in left prefrontal activation in the supplement group only. CONCLUSIONS L and Z supplementation appears to benefit neurocognitive function by enhancing cerebral perfusion, even if consumed for a discrete period of time in late life. (JINS, 2018, 24, 77-90).

Effects of Lutein/Zeaxanthin Supplementation on the Cognitive Function of Community Dwelling Older Adults: A Randomized, Double-Masked, Placebo-Controlled Trial

Background: High levels of xanthophyll carotenoids lutein (L) and zeaxanthin (Z) in the central nervous system have been previously correlated with improved cognitive function in community-dwelling older adults. In this study, we tested the effects of supplementing L and Z on older men and women with a range of baseline cognitive abilities. Objective: The purpose of this study was to determine whether or not supplementation with L+Z could improve cognitive function in community-dwelling, older adults. Design: Double-masked, randomized, placebo-controlled trial. A total of 62 older adults were randomized into groups receiving either 12 mg L+Z or a visually identical placebo. Data from 51 participants (M = 73.7 years) were available for analysis. Retinal L+Z levels (macular pigment optical density, MPOD) were measured psychophysically using heterochromatic flicker photometry as a biomarker of cortical L+Z levels. Cognitive function was measured using the CNS Vital Signs computerized test platform. Results: Participants receiving the active L+Z supplement had statistically significant increases in MPOD (p < 0.03) and improvements in complex attention (p < 0.02) and cognitive flexibility domains (p < 0.04), relative to participants taking the placebo. A trend was also seen for the executive function domain (p = 0.073). In male participants only, supplementation yielded improved composite memory (p = 0.04). Conclusions: Supplementation with L+Z improved cognitive function in community-dwelling, older men and women.

Critical Flicker Fusion Predicts Executive Function in Younger and Older Adults

Critical flicker fusion (CFF), a measure of visual processing speed, has often been regarded as a basic metric underlying a number of higher cognitive functions. To test this, we measured CFF, global cognition, and several cognitive subdomains. Because age is a strong covariate for most of these variables, both younger (n = 72) and older (n = 57) subjects were measured. Consistent with expectations, age was inversely related to CFF and performance on all of the cognitive measures except for visual memory. In contrast, age-adjusted CFF thresholds were only positively related to executive function. Results showed that CFF predicted executive function across both age groups and accounted for unique variance in performance above and beyond age and global cognitive status. The current findings suggest that CFF may be a unique predictor of executive dysfunction.

Relation of Retinal and Serum Lutein and Zeaxanthin to White Matter Integrity in Older Adults: A Diffusion Tensor Imaging Study

Objective Lutein (L) and zeaxanthin (Z) are phytonutrients that accumulate in human brain tissue and positively impact cognition. Given their antioxidant and anti-inflammatory properties and their role in stabilizing cell membranes, L&Z may relate to measures of white matter integrity (WMI). Method The current study tested the relation of retinal (macular pigment optical density/MPOD) and blood serum concentrations of L&Z to WMI in community-dwelling older adults (n = 54) using diffusion tensor imaging (DTI). Younger adults (n = 38) were recruited as a control group to confirm age-related changes in WMI. A priori analyses focused on four regions of interest (ROIs-genu of the corpus callosum, cingulum, fornix, and uncinate fasciculus). Exploratory whole-brain analyses were also conducted. Results Consistent with previous literature, age group (young vs. old) negatively predicted WMI globally, in the genu, cingulum, and fornix (p < .001). ROI analysis in the older adult sample showed relations of MPOD and serum L&Z to better WMI in the uncinate fasciculus and cingulum (p < .05, FWE-corrected). Whole-brain analysis suggested associations between L&Z and WMI in both anterior white matter tracts vulnerable to age-related decline and posterior tracts (p < .01, uncorrected). Conclusions The current study is among the first to use neuroimaging to measure the relation of L&Z to brain structure in vivo. Results confirm previous findings that L&Z influence white matter integrity, particularly in regions vulnerable to age-related decline. The current study contributes to a growing literature investigating the relationship between diet and neural integrity by identifying white matter tracts that may be associated with modifiable dietary factors in older adults.

Effects of a Lutein and Zeaxanthin Intervention on Cognitive Function: A Randomized, Double-Masked, Placebo-Controlled Trial of Younger Healthy Adults

Background: Past studies have suggested that higher lutein (L) and zeaxanthin (Z) levels in serum and in the central nervous system (as quantified by measuring macular pigment optical density, MPOD) are related to improved cognitive function in older adults. Very few studies have addressed the issue of xanthophylls and cognitive function in younger adults, and no controlled trials have been conducted to date to determine whether or not supplementation with L + Z can change cognitive function in this population. Objective: The purpose of this study was to determine whether or not supplementation with L + Z could improve cognitive function in young (age 18–30), healthy adults. Design: A randomized, double-masked, placebo-controlled trial design was used. Fifty-one young, healthy subjects were recruited as part of a larger study on xanthophylls and cognitive function. Subjects were randomized into active supplement (n = 37) and placebo groups (n = 14). MPOD was measured psychophysically using customized heterochromatic flicker photometry. Cognitive function was measured using the CNS Vital Signs testing platform. MPOD and cognitive function were measured every four months for a full year of supplementation. Results: Supplementation increased MPOD significantly over the course of the year, vs. placebo (p < 0.001). Daily supplementation with L + Z and increases in MPOD resulted in significant improvements in spatial memory (p < 0.04), reasoning ability (p < 0.05) and complex attention (p < 0.04), above and beyond improvements due to practice effects. Conclusions: Supplementation with L + Z improves CNS xanthophyll levels and cognitive function in young, healthy adults. Magnitudes of effects are similar to previous work reporting correlations between MPOD and cognition in other populations.

Lutein and Zeaxanthin Are Positively Associated with Visual–Spatial Functioning in Older Adults: An fMRI Study

Lutein (L) and zeaxanthin (Z) are two xanthophyll carotenoids that have antioxidant and anti-inflammatory properties. Previous work has demonstrated their importance for eye health and preventing diseases such as age-related macular degeneration. An emerging literature base has also demonstrated the importance of L and Z in cognition, neural structure, and neural efficiency. The present study aimed to better understand the mechanisms by which L and Z relate to cognition, in particular, visual–spatial processing and decision-making in older adults. We hypothesized that markers of higher levels of L and Z would be associated with better neural efficiency during a visual–spatial processing task. L and Z were assessed via standard measurement of blood serum and retinal concentrations. Visual–spatial processing and decision-making were assessed via a judgment of line orientation task (JLO) completed during a functional magnetic resonance imaging (fMRI) scan. The results demonstrated that individuals with higher concentrations of L and Z showed a decreased blood-oxygen-level dependent (BOLD) signal during task performance (i.e., “neural efficiency”) in key areas associated with visual–spatial perception, processing, decision-making, and motor coordination, including the lateral occipital cortex, occipital pole, superior and middle temporal gyri, superior parietal lobule, superior and middle frontal gyri, and pre- and post-central gyri. To our knowledge, this is the first investigation of the relationship of L and Z to visual–spatial processing at a neural level using in vivo methodology. Our findings suggest that L and Z may impact brain health and cognition in older adults by enhancing neurobiological efficiency in a variety of regions that support visual perception and decision-making.

Education Differentially Buffers Cognitive Performance in Black and White Older Adults

Objectives Given that black American older adults are more likely to have lower educational attainment and perform worse on cognitive tests than white Americans, we examined whether increased education would confer greater cognitive advantage to black Americans on measures of global and specific domains of cognitive function. Methods The sample included 522 community-dwelling older adults from a larger study. An analysis of covariance was conducted with race and education as between-participant factors and global cognition as the dependent variable. A multivariate analysis of covariance was conducted with five cognitive domains (immediate memory, visuospatial/constructional ability, language, attention, and delayed memory) as the dependent variables. Results Significant main effects indicated that black Americans, F(1,516) = 29.18, p < .001, and individuals with less education, F(1,516) = 44.93, p < .001, evidenced lower cognitive functioning, controlling for age and overall health status, and the interaction term reached statistical significance, F(1,516) = 7.95, p = .005. The impact of education on global cognitive function for black participants was more than twice as large (Cohens d = 1.30) than for white participants (Cohens d = .52). There was a significant race × education interaction for the cognitive domain of attention (p < .001) and a composite measure of non-memory domains (i.e., language, visuospatial/constructional, and attention; p < .001). Discussion Our findings suggest that educational attainment is particularly important for black Americans with respect to global cognitive function, attention, and non-memory domains.

Body mass index and its relation to neuropsychological functioning and brain volume in healthy older adults

Abstract Obesity is a growing concern worldwide because of its adverse health effects, including its negative impact on cognitive functioning. This concern is especially relevant for older adults, who are already likely to experience some cognitive decline and loss of brain volume due to aging, (Gea et al., 2002). However, there is some evidence that higher body mass index (BMI) may actually be protective in later life (Hughes et al., 2009; Luchsinger et al., 2007; Nilsson and Nilsson, 2009; Sturman et al., 2008). Therefore, the purpose of the current study was to assess the relationship between BMI and neuropsychological functioning in older adults, and concurrently the relationship between BMI and brain volume. Older adults (N = 88) reported height and weight to determine BMI (M = 26.5) based on Centers for Disease Control and Prevention (CDC) guidelines. Cognitive function was assessed with the Repeatable Battery for Assessment of Neuropsychological Status (RBANS). Brain volume measurements were evaluated via structural MRI. Results indicated no association between BMI and neuropsychological functioning. There was a significant association between BMI and total grey matter volume while controlling for age and years of education (&bgr; = 0.208, p = .026, &Dgr;R2 = 0.043), indicating that as BMI increased, brain volume in these areas modestly increased. However, these results did not survive multiple comparison corrections and were further attenuated to near significance when sex was explicitly added as an additional covariate. Nevertheless, while replication is clearly needed, these results suggest that moderately greater BMI in later life may modestly attenuate concomitant grey matter volume decline.

Executive function moderates the relationship between physical performance and functional independence in older adults

We translated the test “partial knowledge of abstract words” into Thai and investigated the occurrence of partial knowledge effects in the conceptual domain of abstract words in individuals with frontotemporal dementia-semantic dementia (FTD-SD), Alzheimer disease (AD), and other dementia. Twelve FTD-SD, 14 AD, 7 non-amnestic mild cognitive impairment (non-am MCI), 3 other dementia, and 10 healthy controls were examined with 3 level synonym comprehension abstract word test. They include antonym distractors, distant distractors, and close distractors. Results: Mean scores of the antonym distractors, distant distractors, and close distractors of dementia groups and controls were displayed in figure 1. All dementia groups showed weaker performance on choosing distant distractors and close distractors, which requires a fine specification of word meaning, than controls. The impairment of partial knowledge of abstract words was greater in those with SD than AD compared to controls (SD: antonym distractor SE1⁄43.43 p1⁄40.034, distant distractors SE1⁄43.36, p1⁄40.001, close distractor SE 1⁄42.69, p1⁄40.002; AD: antonym distractor SE1⁄43.31, p1⁄40.03, distant distractors SE1⁄43.25, p1⁄40.005, close distractor SE1⁄42.6, p1⁄40.016). We found that 3 subjects with Parkinson dementia and vascular dementia performed worst. However, the number of subjects in this group was small. Conclusions: These findings demonstrate that a degraded conceptual knowledge of abstract words is a phenomenon in neurodegenerative diseases and vascular dementia. Detailed information of abstract words is more affected than broad-sense information.

Cognitive functioning mediates the relationship between social functioning and activities of daily living in older adults

Results: A cumulative cognitive quotient crossing one percentile interval line distinguished healthy controls from thosewho developed dementia with a sensitivity and specificity of 80%. Based on the 10year follow-up data, a sensitivity of 78% and specificity of 84%, positive predictive value was just over 50% (likely a reflection of the relatively weak diagnostic power of the MMSE), but negative predictive value was very high at 95%. Similar findings were noted for the 5-year follow data (sensitivity 80%, specificity 80%, positive predictive value 45%, negative predictive value 95%). Altogether, these results suggest that cognitive charts are highly efficient in identifying elderly individuals who are cognitively stable over time despite an overt decline in their scores on repeat MMSE. Conclusions: Similar to ‘growth charts’, we propose a method which factors in age and education to help determine whether elderly individuals show abnormal performance on serial MMSE. A significant decline on cognitive charts should prompt further investigation while a non-significant decline reliably identifies those individuals who do not need further cognitive work up.