The path between socioeconomic inequality and cognitive function: A mediation analysis based on the HAALSI cohort in rural South Africa

Background

Socioeconomic position (SEP) strongly predicts late-life cognitive health, yet the pathways between SEP and cognitive function remain unclear. This study assessed whether and to what extent the association between SEP and cognitive function in the adult population in rural South Africa is mediated by some health conditions, behavioral factors, and social capital factors.

Methods

In this cross-sectional study, we used data from the 2014–15 “Health and Aging Africa: A Longitudinal Study of an INDEPTH Community in South Africa” (HAALSI) cohort, including 5,059 adults aged 40+ years from the Agincourt sub-district in Mpumalanga Province, South Africa. SEP, the independent variable, was measured based on ownership of household goods. Cognitive function, the dependent variable, was assessed using questions related to time orientation and immediate and delayed word recall. We used the multiple-mediation analysis on 4125 individuals with complete values on all variables to assess the mediating roles of health conditions (hypertension, diabetes, obesity, and disability), behavioral factors (leisure physical activity, alcohol consumption, and tobacco smoking), and social capital factors (community's willingness to help, trust, sense of safety, and social network contact) in the association between SEP and cognitive function.

Results

Compared to adults in the poorest wealth quintile, those in the richest wealth quintile had better cognition (β = 0.903, p < 0.001). The mediation analysis revealed that health conditions mediated 20.7% of the total effect of SEP on cognitive function. In comparison, 3.3% was mediated by behavioral factors and only 0.7% by social capital factors. In the multiple-mediator model, 17.9% of the effect of SEP on cognitive function was jointly mediated by health conditions, behavioral factors, and social capital factors.

Conclusion

Low socioeconomic position is a significant factor associated with poor cognitive function among adults aged 40 years and above in South Africa. Health conditions mainly mediate the effects between SEP and cognitive function. Therefore, actions to prevent and control chronic health conditions can serve as the entry point for intervention to prevent poor cognitive function among people with low socioeconomic status.

Inflammation, Executive Function, and Adiposity in Children With or at Risk for Obesity: A Pilot Study

OBJECTIVE

Obesity is associated with executive function (EF) deficits across the lifespan. Higher body mass index (BMI), obesity severity, and poorer adherence and weight outcomes in obesity treatment have all been associated with EF deficits. Adult literature has begun to emphasize neuroinflammation in obesity as a possible pathway to later cognitive impairment in EF. However, pediatric obesity literature has yet to establish associations between peripheral inflammation and EF. Thus, the present study examined associations and variability in inflammation, EF, and adiposity in children with or at risk for obesity. Additionally, inflammation was examined as a mediator of the relationship between adiposity and EF.

METHODS

Children (N = 39) aged 8-12 years with BMI ≥ 50th percentile were recruited. The NIH Toolbox Cognitive Battery was used to assess performance-based EF. Peripheral inflammation was assessed in fasted sera. Dual-energy X-ray absorptiometry scans were conducted to assess body composition. Linear regression and Hayes' PROCESS Model 4 (Hayes, 2017) were used to evaluate associations between adiposity and inflammation, inflammation and EF, and whether adiposity effects EF through its effect on inflammation.

RESULTS

Positive associations were identified between adiposity and inflammation, and negative to null associations were identified between inflammation and EF. Medium indirect effects of adiposity on EF through inflammation were detected.

CONCLUSION

Pilot evidence suggests greater adiposity is linked with greater inflammation, which in turn is associated with less EF in some domains. Directionality and causality cannot yet be established, but with replication, findings may inform efforts to target EF in pediatric obesity.

Association of inflammation and cognition in the elderly: A systematic review and meta-analysis

Background

The development of mild cognitive impairment (MCI) and Alzheimer's disease (AD) may be associated with an inflammatory process. Inflammatory cytokines may be a surrogate for systemic inflammation leading to worsening neurological function. We aim to investigate the association between cognitive impairment and inflammation by pooling and analyzing the data from previously published studies.

Methods

We performed a systematic literature search on MEDLINE, PubMed, Embase, Web of Science, and Scopus for prospective longitudinal and cross-sectional studies evaluating the relationship between inflammation and cognitive functions.

Results

A total of 79 articles were included in our systematic review and meta-analysis. Pooled estimates from cross-sectional studies have demonstrated an increased level of C-reactive protein (CRP) [Hedges's g 0.35, 95% CI (0.16, 0.55), p < 0.05], IL-1β [0.94, 95% CI (-0.04, 1.92), p < 0.05], interleukin-6 (IL-6) [0.46, 95% CI (0.05, 0.88), p < 0.005], TNF alpha [0.22, 95% CI (-0.24, 0.68), p < 0.05], sTNFR-1 [0.74, 95% CI (0.46, 1.02), p < 0.05] in AD compared to controls. Similarly, higher levels of IL-1β [0.17, 95% CI (0.05, 0.28), p < 0.05], IL-6 [0.13, 95% CI (0.08, 0.18), p < 0.005], TNF alpha [0.28, 95% CI (0.07, 0.49), p < 0.05], sTNFR-1 [0.21, 95% CI (0.05, 0.48), p < 0.05] was also observed in MCI vs. control samples. The data from longitudinal studies suggested that levels of IL-6 significantly increased the risk of cognitive decline [OR = 1.34, 95% CI (1.13, 1.56)]. However, intermediate levels of IL-6 had no significant effect on the final clinical endpoint [OR = 1.06, 95% CI (0.8, 1.32)].

Conclusion

The data from cross-sectional studies suggest a higher level of inflammatory cytokines in AD and MCI as compared to controls. Moreover, data from longitudinal studies suggest that the risk of cognitive deterioration may increase by high IL-6 levels. According to our analysis, CRP, antichymotrypsin (ACT), Albumin, and tumor necrosis factor (TNF) alpha may not be good surrogates for neurological degeneration over time.

Relationship between Depression with Physical Activity and Obesity in Older Diabetes Patients: Inflammation as a Mediator

Obesity and physical activity (PA) may affect inflammation and are also related to depression. This study aimed to explore the association between depression, obesity, and PA in older diabetes patients mediated by inflammation. We conducted a cross-sectional study with 197 elderly diabetes patients (≥65 y/o). Participants were interviewed to gather demographic and lifestyle data. Assessment of depression was based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. High-sensitivity C-reactive protein was used as a marker of inflammation. Participants with a body mass index (kg/m2) ≥ 27 were considered to be obese. Our data indicated that among all participants with (n = 57) and without (n = 140) depression, older diabetes patients with depression had a lower intake of energy and protein and a lower prevalence of smoking and alcohol consumption than those without depression (p < 0.05). We also found that inflammation may be a partial mediator in the relationship between obesity and depression, and a significant mediator between PA and depression. Additionally, a regression model of obesity and PA showed that PA was a significant predictor of inflammation. However, the association between obesity and inflammation was not significant. When obesity, PA, and inflammation were included in a regression model together, inflammation significantly predicted depression (OR = 4.18, p = 0.004). The association between obesity and depression was also significant (OR = 2.45, p = 0.038). However, the association between PA and depression was not significant, and the mediating effect of inflammation was significant according to the Sobel test (z = −2.01, p = 0.045). In conclusion, the beneficial effects of PA may lower levels of inflammation produced by obesity, thus reducing inflammatory effects that may be related to depression. Overall, inflammation may mediate the relationship between depression and PA in older diabetes patients.

Mediation effects of diabetes and inflammation on the relationship of obesity to cognitive impairment in African Americans

BACKGROUND

Whether diabetes and adipokine-driven inflammation explain the association of obesity to cognitive impairment is unknown.

METHODS

Structural equation models estimated the total effects of waist circumference on cognitive outcomes among African American participants cross-sectionally (index exam) and longitudinally. Total effects were deconstructed into direct pathways of waist circumference to cognitive impairment and indirect mediation pathways through leptin, soluble tumor necrosis factor receptor 2 (sTNFR2), and diabetes. Waist circumference, leptin, and sTNFR2 were standardized. Cognitive impairment was defined as MMSE <21 or a z-score < -1.5 standard deviation (SD). Incident cognitive impairment was defined among those without cognitive impairment at the index exam as follow-up MMSE<21, z- score < -1.5, MMSE decline >1 point/year, or z-score decline of >0.1 SD/year.

RESULTS

Among 1008 participants (70% women, mean age 62.9 years, 14.5% with obesity, 26% with diabetes), 132 (13%) had baseline cognitive impairment. Each SD higher waist circumference was associated with higher odds of cognitive impairment, odds ratio (OR) = 1.63; (95% confidence interval: 1.17, 2.24), with mediating pathways explaining 65% of the total effect (58% from diabetes; 7% from inflammation). At follow-up (mean 6.8 years), 106 of 535 (19.8%) had developed cognitive impairment. Each SD higher waist circumference was associated with higher odds of developing cognitive impairment (OR = 1.87; 95%CI: 1.18, 2.74); the direct effect of waist circumference explained 37% of the total effect and mediating pathways explained 63% (61% from diabetes; 2% from inflammation), although individual pathways were not statistically supported in the smaller sample.

CONCLUSION

Diabetes, and to a lesser degree, adiposity-driven inflammation, appear to explain a substantial proportion of abdominal adiposity relationships with cognitive impairment. The impact of preventing and treating obesity on cognitive outcomes merits study.

Truncal Fat and Frailty Are Important Predictors of Cognitive Performance among Aging Adults with Obesity

OBJECTIVES

To explore associations among cognition, frailty, and obesity in older adults.

DESIGN

Descriptive, secondary analysis of baseline data from two related lifestyle intervention trials.

SETTING

Clinical study open to civilian population through the Center for Translational Research on Inflammatory Diseases at the Veterans Affairs Medical Center in Houston, TX.

PARTICIPANTS

One hundred eight community-dwelling adults with obesity, aged 65 or older, recruited consecutively from two lifestyle intervention trials.

MEASUREMENTS

Cognition was assessed using Composite Age-Adjusted Scale Score from the National Institutes of Health Toolbox Cognition Battery: Obesity was assessed by body mass index (BMI) and also by truncal fat mas via dual energy x-ray absorptiometry. Frailty was assessed using the Physical Performance Test.

RESULTS

A significant linear regression model for cognition revealed frailty as the strongest predictor, followed by sex, and then truncal fat (R2=0.340, p<0.001).

CONCLUSION

Cognition among community-dwelling older adults with obese BMI may worsen with greater truncal fat mass. Frailty appears to be an important predictor of cognitive performance in this population.

Body Mass Index Predicts Decline in Executive Function in Bipolar Disorder: Preliminary Data of a 12-Month Follow-up Study

INTRODUCTION

Obesity and associated risk factors have been linked to cognitive decline before.

OBJECTIVES

In the present study, we evaluated potential cumulative negative effects of overweight and obesity on cognitive performance in euthymic patients with bipolar disorder (BD) in a longitudinal design.

METHODS

Neurocognitive measures (California Verbal Learning Test, Trail Making Test [TMT] A/B, Digit-Symbol-Test, Digit-Span, d2 Test), anthropometrics (e.g., body mass index [BMI]), and clinical ratings (Hamilton Depression Scale, Young Mania Rating Scale) were collected over a 12-month observation period. Follow-up data of 38 patients with BD (mean age 40 years; 15 males, 23 females) were available.

RESULTS

High baseline BMI predicted a decrease in the patient's performance in the Digit-Span backwards task measuring working memory performance. In contrast, cognitive performance was not predicted by increases in BMI at follow-up. Normal weight bipolar patients (n = 19) improved their performance on the TMT B, measuring cognitive flexibility and executive functioning, within 1 year, while overweight bipolar patients (n = 19) showed no change in this task.

CONCLUSIONS

The results suggest that overweight can predict cognitive performance changes over 12 months.

Obesity, putative biological mediators, and cognitive function in a national sample of children and adolescents

Childhood obesity has reached epidemic rates nationwide and may be associated with impaired cognitive function. A growing body of evidence suggests that poorer academic performance for children with obesity and overweight is related to declines in executive function skills. This study aimed to identify biological mediators between obesity and overweight and cognitive function among children and adolescents. A total of 3323 children aged 6-16 years from the Third National Health and Nutrition Examination Survey between 1988 and 1994 (NHANES III) was used to measure associations between measures of obesity and overweight, cognitive function (IQ test batteries), iron deficiency, inflammation (c-reactive protein), and glucose metabolism (glycosylated hemoglobin) using multiple mediation models. Approximately 15% of the children were overweight and 11% were obese. Results showed lower scores for children who were obese or overweight than children of normal weight on several IQ subtest batteries. Obesity and overweight were also associated with biological mediators such as iron deficiency, elevated c-reactive protein and glycosylated hemoglobin. Several biomarkers of iron status were also related to measures of cognitive function. Early declines in cognitive function are associated with biomarkers of iron deficiency and inflammation in children and adolescents, and while some biological linkages between obesity and overweight and cognitive function are identified herein, further study is needed to identify additional biological mediators between obesity and overweight and cognitive function in pediatric populations.

Adiposity, Inflammation, and Working Memory: Evidence for a Vicious Cycle

Overweight and obesity constitute the fifth leading cause of preventable deaths worldwide. One pathway through which excess weight contributes to poor health outcomes is via inflammatory activity and changes in cognitive processes. Prior theory has proposed a vicious cycle whereby obesity potentiates inflammatory activity, which alters cognitive processes such as working memory, which in turn leads to a reduced ability to self-regulate and therefore manage weight. However, to date no longitudinal studies have examined this potential dynamic. In the current study, we addressed this gap by assessing the relations among fat mass, C-reactive protein (CRP), and working memory across time in a large sample of 8536 children followed through adolescence in the Avon Longitudinal Study of Parents and Children in the United Kingdom. Adiposity was quantified via dual emission x-ray absorptiometry (DEXA) at ages 9 and 15.5 years old, and inflammatory activity was indexed via circulating serum C-reactive protein (CRP) levels assessed with a high-sensitivity assay at those same ages. Working memory was assessed between these two time points, at age 10, permitting examination of the temporal relations between working memory, adiposity, and inflammatory activity. As hypothesized, we found that fat mass predicted later poor working memory, and this association was statistically mediated by CRP. Further, we found that poor working memory predicted greater subsequent fat mass and CRP, and the link between working memory and subsequent CRP was partially mediated by fat mass. These results thus could be taken to suggest the existence of a vicious cycle of mutually amplifying adiposity, inflammatory activity, and poor working memory over time.

•

Adiposity and inflammatory activity (CRP) was measured at ages 9 and 15.5 ​yrs.

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Working memory was assessed at age 10 ​yrs.

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Adiposity predicted working memory, and this association was mediated by CRP.

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Working memory predicted later adiposity and CRP, this was mediated by adiposity.

Elevated Fasting Plasma Glucose Is Associated With an Increased Risk of MCI: A Community-Based Cross-Sectional Study

BACKGROUND

Mild cognitive impairment (MCI) is a transitional state between normal elderly people and dementia, with a higher risk of dementia transition. The primary purpose of the current study was to investigate whether routine blood and blood biochemical markers could be used to predict the onset of MCI.

METHODS

Data was obtained from the cohort study on brain health of the elderly in Shanghai. A total of 1015 community elders were included in the current study. Based on clinical evaluation and the scores of Montreal Cognitive Assessment (MoCA), these participants were divided into the MCI (n=444) and cognitively normal groups (n=571). Then we tested their fasting blood routine and blood biochemical indexes, and collected their general demographic data by using a standard questionnaire.

RESULTS

By using binary logistic regression analysis and the ROC curve, we found that elevated fasting plasma glucose (p=0.025, OR=1.118, OR=1.014-1.233) was a risk factor for MCI.

CONCLUSIONS

Elevated fasting blood glucose may be a risk factor for mild cognitive impairment, but the above conclusions need to be verified by longitudinal studies.

Association Between Lipid Accumulation Product and Mild Cognitive Impairment in Patients with Type 2 Diabetes

BACKGROUND

Diabetes may increase the risk of conversion of mild cognitive impairment (MCI) to dementia. Lipid accumulation product (LAP), an index of visceral obesity, has been shown to be a powerful predictor of insulin resistance and type 2 diabetes (T2D). However, little attention has been paid to the relationship between LAP and MCI in T2D.

OBJECTIVE

We aimed to investigate the association between the LAP index and MCI in patients with T2D.

METHODS

In total, 220 hospitalized patients with T2D, including 113 MCI patients and 107 patients with normal cognition, were enrolled in this cross-sectional study. We collected demographic, anthropometric, and biochemical data on each subject. The LAP index was calculated according to the following formulas: [waist circumference (WC) (cm) - 65]×triglyceride (TG) (mmol/L) for males and [WC (cm) - 58] ×TG (mmol/L) for females.

RESULTS

Compared with patients with normal cognition, MCI patients were older and had a higher LAP index, WC, body mass index, and glycosylated hemoglobin A1c level, as well as a lower Montreal Cognitive Assessment score and education level (p < 0.05). After adjusting for confounding factors, LAP index was associated with MCI (OR = 1.047, 95% CI = 1.031-1.063, p < 0.01). The area under the ROC curve (AUC) for the LAP index was higher than that for WC and BMI.

CONCLUSION

A high LAP index is associated with an increased risk of MCI in T2D patients. The LAP index appears to be a good indicator of risk of MCI in patients with T2D.

Body mass index across adult life and cognitive function in the American elderly

This study aimed to examine the associations of body mass index (BMI) across adult life with cognitive function in 2,637 participants aged 60 years or over from NHANES 2011-2014. The primary outcome was a composite score based on test scores on word list learning, animal naming, and digit symbol substitution. Exposures of interest included BMI at age 25, BMI 10 years before the survey, BMI at the survey (current BMI), and BMI burden calculated from age 25 to age at survey. BMI at age 25 was inversely associated with the composite score (β=-0.0271±0.0130 per kg/m², P=0.038) and positively with low cognitive performance (odd ratio=1.04, 95% confidence interval: 1.01-1.07, P=0.010), defined as below 20 percentile of the composite score. Similar results were observed for BMI 10 years before the survey and BMI burden. Current BMI was positively associated with the composite score (β=0.0369±0.0113, P=0.001) and inversely associated with low cognitive performance (odd ratio=0.96, 95% confidence interval: 0.94-0.99, P=0.004). In conclusion, high BMI in early adult life is associated with low cognitive function in late life, which underscores the importance of a healthy body weight across the life course. The association between BMI and cognitive function at late life requires further investigation.

Cognitive, Olfactory, and Affective Determinants of Body Weight in Aging Individuals

OBJECTIVE

A complex interplay of factors including cognitive, sensory and affective aspects has been associated in a controversial way with anthropometric measures related to body weight.

METHODS

Here we propose two studies to investigate whether and how cognitive, olfactory and affective variables resulted associated with body weight during healthy aging. In Study 1, we investigated the cognitive status, the odor identification skills, and the BMI of 209 individuals (50-96 yo). In Study 2 an extensive evaluation of cognitive functions (in particular executive functions and memory), odor threshold, discrimination and identification and affective skills (i.e., depression and anxiety) was performed in a group of 35 healthy, free-living aging individuals (58-85 yo).

RESULTS

In Study 1, greater BMI was not associated with performance on the odor identification task but was significantly associated with better cognitive skills. In Study 2, we observed that executive functions seemed to favor a successful managing of body weight, and individuals with greater BMI and waist circumference showed significantly better odor discrimination skills. Finally, lower waist circumference (but not BMI) was found significantly associated with greater levels of anxiety.

CONCLUSIONS

These results confirm that cognitive, olfactory and affective factors may influence body weight during healthy aging.

Perioperative Heart-Brain Axis Protection in Obese Surgical Patients: The Nutrigenomic Approach

The number of obese patients undergoing cardiac and noncardiac surgery is rapidly increasing because they are more prone to concomitant diseases, such as diabetes, thrombosis, sleep-disordered breathing, cardiovascular and cerebrovascular disorders. Even if guidelines are already available to manage anesthesia and surgery of obese patients, the assessment of the perioperative morbidity and mortality from heart and brain disorders in morbidly obese surgical patients will be challenging in the next years. The present review will recapitulate the new mechanisms underlying the Heart-brain Axis (HBA) vulnerability during the perioperative period in healthy and morbidly obese patients. Finally, we will describe the nutrigenomics approach, an emerging noninvasive dietary tool, to maintain a healthy body weight and to minimize the HBA propensity to injury in obese individuals undergoing all types of surgery by personalized intake of plant compounds that may regulate the switch from health to disease in an epigenetic manner. Our review provides current insights into the mechanisms underlying HBA response in obese surgical patients and how they are modulated by epigenetically active food constituents.

Metabolic Syndrome and Cognitive Function: Cross-Sectional Study on Community-Dwelling Non-Demented Older Adults in Japan

AIM

This is a cross-sectional study of relation between metabolic syndrome and cognitive function in community-dwelling non-demented older adults in Japan. We examine the effect of metabolic syndrome and its components on global cognitive function. We also aim to clarify differences of specific cognitive domains between the subjects with and without metabolic syndrome.

METHODS

We studied 2150 subjects aged between 60 and 90 years whose scores on mini mental state examination (MMSE) were over 23 points. We analyzed difference in MMSE scores between the subjects with and without metabolic syndrome. Logistic regression analysis was performed with MMSE score as the dependent variable and metabolic syndrome components as the independent variable adjusted with age. We also examined differences in attention, logical memory, and verbal and category fluency between the subjects with and without metabolic syndrome.

RESULTS

MMSE scores were not significantly different between subjects with and without metabolic syndrome. In logistic regression analysis, the score of MMSE was significantly negatively associated with triglycerides in males and significantly negatively associated with abdominal circumference in females. Subjects with metabolic syndrome showed significantly lower performance of attention tasks compared to subjects without metabolic syndrome.

CONCLUSIONS

Our results suggest that in community-dwelling non-demented Japanese older adults, attention but not global cognitive function may be impaired by metabolic syndrome. Inverted association between some components of metabolic syndrome and global cognitive function indicate necessity of further studies on the relation between undernutrition and cognitive function.

Social network types and cognitive decline among older Korean adults: A longitudinal population-based study

OBJECTIVES

Social network (SN) has been known to impact on cognitive function in late life. However, knowledge regarding the link between SN of various types and cognitive decline (CD) is limited. This study's aim was to investigate which types of SN are associated with reduced risk of CD 2 years later among community-dwelling older adults.

METHODS

Secondary analysis of data from 1960 cognitively intact adults 65 years of age or older who participated in the Korean Longitudinal Study of Aging (KLoSA) was employed. K-means cluster analysis was conducted to derive SN types using seven common SN characteristics (marital status, living with children, number of children, frequency of contact with children, frequency of contact with friends, frequency of participation in religious activities, and frequency of participation in social groups). Multivariable linear regression analysis regarding the effects of SN type on CD between 2012 and 2014 was conducted, controlling for covariates.

RESULTS

K-means cluster analyses identified a model with five types of SN as being most optimal, and they were named diverse/couple, diverse/family, congregant, restricted/married, and widowed. The average CD 2 years later was most pronounced in those in the widowed network. Compared with the widowed, older adults in the diverse/couple network and the congregant network at baseline had a lower risk of CD 2 years after initial assessment.

CONCLUSIONS

Findings show that older Korean adults embedded in widowed network types are at risk for CD and suggest the importance of having a spouse and religious group activities in maintaining cognitive function in later life.

High fat-low protein diet induces metabolic alterations and cognitive dysfunction in female rats

Approximately one-third of the world population is suffering from MetS, and the same is expected to rise in the years to come. Worldwide, most of the staple diets contain high amounts of carbohydrates, fats and comparatively low quantities of proteins. The goal of this study was to evaluate the effect of high fat-low protein diet in the development of the metabolic syndrome and associated cognitive deficits in the female rats. The rats fed with high fat-low protein diet (HFLPD) and 15% oral fructose solution for 24 weeks. Body weight, food intake, water intake, fasting blood glucose, oral glucose tolerance, glycosylated hemoglobin (HbA_1C), and serum lipid profile were measured after every 4 weeks. Serum insulin, HOMA-IR index, rectal temperature, and systolic blood pressure were measured to confirm the manifestation of the hallmarks of metabolic syndrome. Behavioral tests for locomotion, anxiety, learning, and spatial memory were performed from the 12th week to till the end of the study. At the 24th week, oxidative stress assays and histopathology of liver, kidney, brain, and WAT were also performed. HFLPD significantly altered the physiologic and metabolic parameters which contributed to the manifestation of MetS. HFLPD also impaired the cognitive functions along with significant structural changes in the liver, kidney, WAT, and brain. The findings of this study reveal that HFLPD has the potential to induce the physiological, metabolic and histological alterations in rats, which eventually led to the development of MetS and also disrupted the cognitive functions in female rats.

Aging-related changes in fluid intelligence, muscle and adipose mass, and sex-specific immunologic mediation: A longitudinal UK Biobank study

BACKGROUND

Obesity in midlife and early late-life is associated with worse normal cognitive aging. Dual-energy X-ray absorptiometry (DEXA) suggests that visceral adipose mass (VAM) plays a predominant role, whereas non-visceral adipose mass (NVAM) and lean muscle mass (LMM) have shown conflicting relationships. It is unknown how longitudinal, cognitive changes in age-sensitive domains like fluid intelligence (FI) correspond to VAM, NVAM, and LMM in women and men. Furthermore, changes over time in blood leukocyte sub-populations may partially or fully account for sex-specific associations.

METHODS

Data on 4431 late middle-aged, cognitively unimpaired adults (mean = 64.5 y) was obtained from the UK Biobank prospective cohort across 22 centers. FI scores, blood leukocyte counts, and covariates (age, social class, education) were measured at three 2-year intervals over 6 years. DEXA collection overlapped with these intervals. Sex-stratified growth curves, structural equations, and Preacher-Hayes mediation were used to estimate direct and indirect effects. β-weights were standardized.

RESULTS

More LMM predicted gains in FI scores among women (β = 0.130, p < .001) and men (β = 0.089, p < .001). Conversely, more VAM and NVAM independently predicted FI decline equally among sexes (e.g., NVAM: women: β = -0.082, p < .001; men: β = -0.076, p < .001). Among women, FI associations were fully mediated by higher eosinophil counts via VAM (λ = 30.8%, p = .028) and lower lymphocyte counts via LMM (λ = 69.2%, p = .021). Among men, FI associations were partially mediated by lower basophils counts via LMM (λ = 4.5%, p = .042) and higher counts via VAM (λ = 50%, p = .037).

CONCLUSION

The proportion of LMM and VAM equally influenced male FI changes over 6 years, whereas higher LMM among women appeared to more strongly influence. FI changes. Leukocyte counts strongly mediated VAM- and LMM-related FI changes in a sex-specific manner, but not for NVAM. For clinical translation, exercise studies in older adults may benefit from assessing sex-specific values of DEXA-based tissue mass, FI, and leukocyte sub-populations to gauge potential cognitive benefits of less VAM and more LMM.

Neuropsychological Functioning in Older Adults with Obesity: Implications for Bariatric Surgery

Bariatric surgery is the most effective approach to treating morbid obesity, resulting in decreased morbidity, mortality, and improved quality of life. Research on outcomes has generally been restricted to young and middle-aged adults, despite a growing epidemic of obesity in older adults. The use of bariatric surgery has been limited in older individuals, in part due to concerns that preexisting cognitive dysfunction increases the risk of poor post-surgical outcomes, including cognitive decline. The literature on the relationship between obesity and cognition in older adults is emerging, but fraught by several methodological limitations. While there is insufficient research to determine the nature of cognitive outcomes following bariatric surgery in older adults, the aim of this paper is to review the existing evidence and make the case for further study.

Neurocalcin-delta: a potential memory-related factor in hippocampus of obese rats induced by high-fat diet

Introduction

Aberrant protein expression within the hippocampus has recently been implicated in the pathogenesis of obesity-induced memory impairment.

Objectives

The objective of the current study was to search for specific memory-related factors in the hippocampus in obese rats.

Methods

Sprague-Dawley (SD) rats were fed either a high-fat (HF) diet or normal-fat (NF) diet for 10 weeks to obtain the control (CON), diet-induced obese rats (DIO) and diet-resistant (DR) rats. D-galactose was injected subcutaneously for 10 weeks to establish model (MOD) rats with learning and memory impairment. After the hippocampus of the rats sampling, the proteome analysis was conducted using two-dimensional get electrophoresis (2-DE) combined with peptide mass fingerprinting (PMF).

Results

We found 15 differential proteins that expressed in the hippocampus in rats induced by HF diet from the 2-DE map. In addition, Neurocalcin-delta (NCALD) was nearly down-regulated in the DR rats compared with CON rats and MOD rats, which was further confirmed by Western blot, real-time PCR and ELISA results.

Conclusion

Our data demonstrates that the differential memory-related proteins were a reflection of the HF diet, but not potential factors in obesity proneness or obesity resistance. Furthermore, NCALD is proved to be a potential hippocampus-memory related factor related to obesity.

Associations of obesity and weight change with physical and mental impairments in elderly Chinese people

OBJECTIVE

To examine the associations between anthropometric measurements and functional impairments in a sample of urban elderly Chinese people.

METHODS

In two population-based cohort studies, the Shanghai Women's Health Study (SWHS) and Shanghai Men's Health Study (SMHS), 11,505 men and 17,166 women aged 70-88 years at the time of the functional assessment were studied. Weight history was collected and anthropometric data were taken at study enrollment (from 1996 to 2000 for the SWHS, 2002-2006 for the SMHS). Information on functional status and current weight was collected at the most recent follow-up survey (from 2011 to 2015). Logistic regression analyses were applied to estimate the associations of body mass index (BMI), waist-hip-ratio (WHR), and weight changes with functional decline.

RESULTS

After a median follow-up of 14.4 years (range 5.4-18.2 years), we found that BMI/WHR at or after middle age, and weight gain during adulthood were significantly associated with impaired walking ability and mental functioning. Being underweight after age 70 was associated with poorer hearing and/or vision as well as poorer memory. The associations between obesity and functional impairment were generally not modified by sex, comorbidity or exercise.

CONCLUSION

Weight gain, obesity at or after middle age, and underweight after age 70 were associated with physical and mental functional impairments among elderly Chinese people. These findings highlight the importance of maintaining healthy weight to reduce age-related functional decline.