Body mass index and cognitive decline in a biracial community population

Association Between Body Mass Index and Cognitive Function Among Older Adults in India: Findings from a Cross-Sectional Study

OBJECTIVE

The study aimed to explore the association between body mass index (BMI) and cognitive function among older adults in India.

METHODS

Cross-sectional data on 21,000 older adults aged 60 years and older from the first wave of the Longitudinal Ageing Study of India (LASI), conducted in India during 2017-18, were used. Bivariate analysis and multivariate linear regression models were applied. The cognition tests include memory, orientation, arithmetic function, executive function, and object naming.

RESULTS

The mean overall cognition score was 24.6 in the study population. Further, BMI status showed a significant and positive association with cognition. The association of underweight with poor cognition (β=-0.72; 95% CI = -0.89, -0.54) whereas overweight (β = 0.57; 95% CI = 0.39, 0.75) and obese (β = 0.97; 95% CI = 0.68, 1.26) with better cognition remained statistically significant after adjusting for sociodemographic, health-related behavior, and health covariates. The mean cognition score of female older adults was always lower than male older adults with normal BMI, irrespective of their BMI categories.

CONCLUSIONS

This study shows that an underweight BMI is associated with poor cognition in both male and female older adults. In the context of providing health care for older individuals, underweight individuals should be given more attention in India.

The ACTIVE Study: Association of Race and Social Determinants of Health (SDoH) with Long-Term Outcomes and Cognitive Training Effects

Objective: The purpose of this article is to introduce a special issue on the ACTIVE project examining the association between race and social determinants of health (SDoH) and long-term participant outcomes and training effectiveness for older Black/African Americans and Whites in the ACTIVE (for Advanced Cognitive Training for Independent and Vital Elderly) Trial on cognitive abilities, everyday functioning, and incidence of dementia. The ACTIVE study is the largest randomized clinical trial (N = 2802) of the efficacy of three types of cognitive training (memory, reasoning, speed of processing) in improving cognitive and everyday functioning in normal older adults, with follow-ups extending through 5 and 10 years post-intervention. Method: We provide background and context for studying the multiple domains of SDoH in understanding long-term participant outcomes in the ACTIVE trial and racial disparities in the efficacy of cognitive training and summarize the 11 articles in this special issue. Results: Articles in this special issue address several cross-cutting themes. These include 1) a focus on SDoH and race in relation to three cognitive abilities and driving; 2) cognitive training outcomes in older Black/African Americans (B/AA); 3) race differences in everyday function; and 4) associations of various risk factors (e.g., cardiovascular disease, obesity, depression) and protective factors (e.g., occupational complexity) for cognitive decline with health disparities in incident dementia and mortality. Conclusion: In cognitive training studies with cognitively healthy older adults, it is important to consider how factors such as race and SDoH relate to long-term participant outcomes and how they moderate intervention effects.

Associations Between Body Mass Index and Cognitive Change in the ACTIVE Study: Variations by Race and Social Determinants of Health

Objectives: The current study examines relationships between Body Mass Index (BMI) and cognitive performance and change in processing speed, memory, and reasoning, while accounting for variations by race and the influence of social determinants of health. Methods: Secondary data analysis of the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study, which included participants who self-identified as African American or Black (n = 728) and White (n = 2028). Latent growth curve modeling was used to assess study aims. Results: Increases in BMI were associated with less cognitive decline over 10 years across each cognition domain. Race moderation effects were noted for speed and memory. Relationships between BMI and cognitive trajectories were mediated by economic stability for speed and reasoning. Discussion: Overall, these findings are consistent with the "obesity paradox." Further research is needed to elucidate patterns of results by race.

Do Associations Between Vascular Risk and Mild Cognitive Impairment Vary by Race?

Objectives: Given prevalence differences of mild cognitive impairment (MCI) among Black and white older adults, this study aimed to examine whether overall vascular risk factor (VRF) burden and individual VRF associations with amnestic (aMCI) and nonamnestic (naMCI) MCI status varied by Black/white race. Methods: Participants included 2755 older adults without dementia from the ACTIVE study. Comprehensive neuropsychological criteria were used to classify cognitively normal, aMCI, and naMCI. VRFs were primarily defined using subjective report and medication data. Multinomial logistic regression was run predicting MCI subtype. Results: Greater overall VRF burden, high cholesterol, and obesity evinced greater odds of naMCI in Black participants than whites. Across participants, diabetes and hypertension were associated with increased odds of aMCI and naMCI, respectively. Discussion: Results may reflect known systemic inequities on dimensions of social determinants of health for Black older adults. Continued efforts toward examining underlying mechanisms contributing to these findings are critical.

Extended-release metformin improves cognitive impairment in frail older women with hypertension and diabetes: preliminary results from the LEOPARDESS Study

BACKGROUND

Women have a high risk of frailty independently of age and menopause state. Diabetes and hypertension increase the risk of frailty and cognitive impairment. Metformin has been employed in post-menopausal women and some reports have shown encouraging effects in terms of attenuated frailty. However, the impact on cognitive performance of a recently introduced extended-release formulation of metformin has never been explored.

METHODS

We studied consecutive frail hypertensive and diabetic older women presenting at the ASL (local health authority of the Italian Ministry of Health) Avellino, Italy, from June 2021 to August 2022, who were treated or not with extended-release metformin. We included a control group of frail older males with diabetes and hypertension treated with extended-release metformin and a control group of frail older women with diabetes and hypertension treated with regular metformin.

RESULTS

A total of 145 patients successfully completed the study. At the end of the 6-month follow-up, we observed a significantly different cognitive performance compared to baseline in the group of frail women treated with extended-release metformin (p: 0.007). Then, we compared the follow-up groups and we observed significant differences between frail women treated vs. untreated (p: 0.041), between treated frail women and treated frail men (p: 0.016), and between women treated with extended-release metformin vs. women treated with regular metformin (p: 0.048). We confirmed the crucial role of extended-release metformin applying a multivariable logistic analysis to adjust for potential confounders.

CONCLUSIONS

We evidenced, for the first time to the best of our knowledge, the favorable effects on cognitive impairment of extended-release metformin in frail women with diabetes and hypertension.

Overnutrition Induced Cognitive Impairment: Insulin Resistance, Gut-Brain Axis, and Neuroinflammation

Overnutrition-related obesity has become a worldwide epidemic, and its prevalence is expected to steadily rise in the future. It is widely recognized that obesity exerts negative impacts on metabolic disorders such as type 2 diabetes mellitus (T2DM) and cardiovascular diseases. However, relatively fewer reports exist on the impairment of brain structure and function, in the form of memory and executive dysfunction, as well as neurogenerative diseases. Emerging evidence indicates that besides obesity, overnutrition diets independently induce cognitive impairments via multiple mechanisms. In this study, we reviewed the clinical and preclinical literature about the detrimental effects of obesity or high-nutrition diets on cognitive performance and cerebral structure. We mainly focused on the role of brain insulin resistance (IR), microbiota-gut-brain axis, and neuroinflammation. We concluded that before the onset of obesity, short-term exposure to high-nutrition diets already blunted central responses to insulin, altered gut microbiome composition, and activated inflammatory mediators. Overnutrition is linked with the changes in protein expression in brain insulin signaling, leading to pathological features in the brain. Microbiome alteration, bacterial endotoxin release, and gut barrier hyperpermeability also occur to trigger mental and neuronal diseases. In addition, obesity or high-nutrition diets cause chronic and low-grade systematic inflammation, which eventually spreads from the peripheral tissue to the central nervous system (CNS). Altogether, a large number of unknown but potential routes interact and contribute to obesity or diet-induced cognitive impairment. The challenge for future research is to identify effective interventions involving dietary shifts and personalized therapy targeting the underlying mechanisms to prevent and improve cognition deficits.

Are mitophagy enhancers therapeutic targets for Alzheimer's disease?

Healthy mitochondria are essential for functional bioenergetics, calcium signaling, and balanced redox homeostasis. Dysfunctional mitochondria are a central aspect of aging and neurodegenerative diseases such as Alzheimer's disease (AD). The formation and accumulation of amyloid beta (Aβ) and hyperphosphorylated tau (P-tau) play large roles in the cellular changes seen in AD, including mitochondrial dysfunction, synaptic damage, neuronal loss, and defective mitophagy. Mitophagy is the cellular process whereby damaged mitochondria are selectively removed, and it plays an important role in mitochondrial quality control. Dysfunctional mitochondria are associated with increased reactive oxygen species and increased levels of Aβ, P-tau and Drp1, which together trigger mitophagy and autophagy. Impaired mitophagy causes the progressive accumulation of defective organelles and damaged mitochondria, and it has been hypothesized that the restoration of mitophagy may offer therapeutic benefits to AD patients. This review highlights the challenges of pharmacologically inducing mitophagy through two different signaling cascades: 1) The PINK1/parkin-dependent pathway and 2) the PINK1/parkin-independent pathway, with an emphasis on abnormal mitochondrial interactions with Aβ and P-Tau, which alter mitophagy in an age-dependent manner. This article also summarizes recent studies on the effects of mitophagy enhancers, including urolithin A, NAD+, actinonin, and tomatidine, on mutant APP/Aβ and mutant Tau. Findings from our lab have revealed that mitophagy enhancers can suppress APP/Aβ-induced and mutant Tau-induced mitochondrial and synaptic dysfunctions in mouse and cell line models of AD. Finally, we discuss the mechanisms underlying the beneficial health effects of mitophagy enhancers like urolithin A, NAD+, resveratrol and spermidine in AD.

Association of waist-calf circumference ratio with incident cognitive impairment in older adults

BACKGROUND

The longitudinal relation of central fat and muscle mass with cognitive function remains unclear.

OBJECTIVES

We aimed to evaluate the relation of anthropometric measures, including BMI, waist circumference (WC), calf circumference (CC), and waist-calf circumference ratio (WCR), with incident cognitive impairment in older adults.

METHODS

A total of 3312 participants aged ≥65 y (mean: 81.8 y) who were free of cognitive impairment [the Chinese version of the Mini-Mental State Examination (MMSE) scores ≥24 points] in the Chinese Longitudinal Healthy Longevity Survey were included. The primary outcome was incident cognitive impairment, defined as MMSE scores <24 points at the exit visit. Secondary outcomes were incident cognitive decline, defined as a reduction of MMSE scores ≥3 points at the exit visit, and incident decline in different cognitive domains, defined as a reduction of MMSE scores in the domain ≥15% at the exit visit.

RESULTS

During a median follow-up duration of 3.6 y, 565 (17.1%) participants developed incident cognitive impairment. Overall, with mutual adjustments, higher WC [≥89 cm (fourth quartile) compared with <75 cm (first quartile); adjusted HR: 1.56; 95% CI: 1.19, 2.04] and higher WCR [≥2.9 (fourth quartile) compared with <2.4 (first quartile); adjusted HR: 1.96; 95% CI: 1.52, 2.52] were significantly associated with a higher risk of cognitive impairment, and higher CC [≥34 cm (fourth quartile) compared with <28 cm (first quartile); adjusted HR: 0.44; 95% CI: 0.33, 0.59] was associated with a lower hazard of cognitive impairment. Similar results were found for the secondary outcomes. However, BMI was not significantly associated with the study outcomes.

CONCLUSIONS

High WC and low CC were significantly associated with higher incident cognitive impairment in older adults. Moreover, WCR had a relatively stronger association with cognitive impairment compared with each circumference, suggesting maintaining both higher lean mass and lower central fat in older adults for the prevention of cognitive impairment.

Does obesity put your brain at risk?

BACKGROUND AND AIMS

The negative impact of obesity on the brain is an issue of increasing clinical interest. Hence, this review summarized evidence linking obesity with brain morphology (gray and white matter volume), brain function (functional activation and connectivity), and cognitive function.

METHODS

A criticals review of the relevant published English articles between 2008 and 2022, using PubMed, Google Scholar and Science Direct. Studies were included if (1) an experimental/intervention study was conducted (2) the experiment/intervention included both high fat diet or body weight, whether it could counteract the negative effect brain morphological or functional change. Critical analysis for a supporting study was also carried out.

RESULTS

Brain dysfunction can be recognized as result from neuroinflammation, oxidative stress, change in gut-brain hormonal functionality decrease regional blood flow or diminished hippocampal size and change in gut-brain hormonal functionality; which collectively translate into a cycle of deranged metabolic control and cognitive deficits, often obesity referred as changes in brain biochemistry and brain function. Recently, a few changes in brain structure and functions could be traced back even to obese children or adult. Evidence here suggested that obesity elicits early neuroinflammation effects, which likely disrupt the normal metabolism in hypothalamus, and hippocampus result from brain insulin resistance. The mechanisms of these robust effects are discussed herein.

CONCLUSION

Brain disease is inseparable from obesity itself and requires a better recognition to allow future therapeutic targeting for treatment of obesity. Additional research is needed to identify the best treatment targets and to identify if these changes reversible.

Correlation between Body Mass Index (BMI) and Performance on the Montreal Cognitive Assessment (MoCA) in a Cohort of Adult Women in South Africa

Objective. Recent evidence suggests that obesity is increasing worldwide and may negatively impact neurocognition. Local studies on the association of weight status with neurocognitive function are sparse. This study is aimed at examining the association between body mass index (BMI) and neurocognitive functioning scores in a cohort of adult women. Methods. A convenience sample of 175 women aged 18 to 59 years ( $28.03\pm 8.87$ ) recruited in a community-based quantitative study completed the Montreal Cognitive Assessment (MoCA). The BMI metric was used to measure body fat based on weight and height and was stratified as high BMI (overweight or obese) or low BMI (normal weight). The Beck Depression Inventory (BDI) was used to assess depression. Pearson’s correlation analysis and the student’s $t$ -test analysis were performed. Results. We observed a significant inverse association between BMI and performance on MoCA ( $r\left(173\right)=-0.32$ , $p<0.001$ ). Performance on subtest of attention, memory, constructive abstraction, and executive functions significantly and inversely correlated with BMI. Significantly lower scores on the MoCA were found in women with a high BMI compared to women with a low BMI ( $23\pm 4$ vs. $26\pm 3$ ), $t\left(173\right)=4.12$ , $p<0.0001$ ). Conclusions. BMI and MoCA were inversely associated on both global and domain-specific neurocognitive test of attention, memory, and executive function; key neurocognitive control; and regulatory functions underlying behavior and decision-making. The findings provide a rationale for further research into the long-term effects of BMI on neurocognition.

Obesity is associated with greater cognitive function in patients with type 2 diabetes mellitus

BACKGROUND

The impact of obesity on cognitive function in patients with type 2 diabetes mellitus (T2DM) remains controversial. This study aimed to evaluate whether obesity, assessed by body mass index (BMI) was associated with cognitive function among T2DM patients and whether the effect of obesity on cognitive function was through brain structure.

METHODS

This was a post-hoc analysis of the Action to Control Cardiovascular Risk in Diabetes-Memory in Diabetes (ACCORD-MIND) study. The cognitive test battery included the Digit Symbol Substitution Test (DSST), Mini-Mental State Exam (MMSE), Rey Auditory Verbal Learning Test (RAVLT), and STROOP test, which were administered at baseline, and at 20, 40, and 80 months. A subgroup (n = 614) of the ACCORD-MIND study underwent MRI scanning at baseline and at 40 and 80 months. The total brain volume (TBV), abnormal white matter volume (AWM), abnormal gray matter volume (AGM), and abnormal basal ganglia volume (ABG) were estimated. The outcomes of this study were cognitive function and brain structure.

RESULTS

In the adjusted analyses, BMI was positively associated with the MMSE (β:0.08, 95%CI,0.01-0.16, per standard deviation [SD] increase) and RAVLT scores (β:0.09, 95%CI,0.01-0.18). It was also associated with a greater TBV (β:7.48, 95%CI,0.29-14.67). BMI was not associated with the DSST or STROOP scores, and AWM, AGM, ABG. Mediation analysis found that the effect of BMI on MMSE/RAVLT was mediated through TBV.

CONCLUSION

Obesity may be associated with greater cognitive function and the effect of BMI on cognitive function may be mediated by TBV among patients with T2DM.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov, identifier NCT00000620.

Visceral adiposity, inflammation, and hippocampal function in obesity

The 'apple-shaped' anatomical pattern that accompanies visceral adiposity increases risk for multiple chronic diseases, including conditions that impact the brain, such as diabetes and hypertension. However, distinguishing between the consequences of visceral obesity, as opposed to visceral adiposity-associated metabolic and cardiovascular pathologies, presents certain challenges. This review summarizes current literature on relationships between adipose tissue distribution and cognition in preclinical models and highlights unanswered questions surrounding the potential role of tissue- and cell type-specific insulin resistance in these effects. While gaps in knowledge persist related to insulin insensitivity and cognitive impairment in obesity, several recent studies suggest that cells of the neurovascular unit contribute to hippocampal synaptic dysfunction, and this review interprets those findings in the context of progressive metabolic dysfunction in the CNS. Signalling between cerebrovascular endothelial cells, astrocytes, microglia, and neurons has been linked with memory deficits in visceral obesity, and this article describes the cellular changes in each of these populations with respect to their role in amplification or diminution of peripheral signals. The picture emerging from these studies, while incomplete, implicates pro-inflammatory cytokines, insulin resistance, and hyperglycemia in various stages of obesity-induced hippocampal dysfunction. As in the parable of the five blind wanderers holding different parts of an elephant, considerable work remains in order to assemble a model for the underlying mechanisms linking visceral adiposity with age-related cognitive decline.

Visceral adipose NLRP3 impairs cognition in obesity via IL-1R1 on CX3CR1+ cells

Induction of the inflammasome protein cryopyrin (NLRP3) in visceral adipose tissue (VAT) promotes release of the proinflammatory cytokine IL-1β in obesity. Although this mechanism contributes to peripheral metabolic dysfunction, effects on the brain remain unexplored. We investigated whether visceral adipose NLRP3 impairs cognition by activating microglial IL-1 receptor 1 (IL-1R1). After observing protection against obesity-induced neuroinflammation and cognitive impairment in NLRP3-KO mice, we transplanted VAT from obese WT or NLRP3-KO donors into lean recipient mice. Transplantation of VAT from a WT donor (TRANSWT) increased hippocampal IL-1β and impaired cognition, but VAT transplants from comparably obese NLRP3-KO donors (TRANSKO) had no effect. Visceral adipose NLRP3 was required for deficits in long-term potentiation (LTP) in transplant recipients, and LTP impairment in TRANSWT mice was IL-1 dependent. Flow cytometric and gene expression analyses revealed that VAT transplantation recapitulated the effects of obesity on microglial activation and IL-1β gene expression, and visualization of hippocampal microglia revealed similar effects in vivo. Inducible ablation of IL-1R1 in CX3CR1-expressing cells eliminated cognitive impairment in mice with dietary obesity and in transplant recipients and restored immunoquiescence in hippocampal microglia. These results indicate that visceral adipose NLRP3 impairs memory via IL-1-mediated microglial activation and suggest that NLRP3/IL-1β signaling may underlie correlations between visceral adiposity and cognitive impairment in humans.

Changes in Body Mass Index Are Related to Faster Cognitive Decline Among African American Older Adults

BACKGROUND/OBJECTIVES

The purpose of this study was to: (1) examine relationships between body mass index (BMI) stability and cognitive decline in older African Americans; and (2) investigate differences in the relationships between women and men.

DESIGN

The present study is a secondary data analysis of the Minority Aging Research Study, which is a longitudinal, cohort study of risk factors for cognitive decline and Alzheimer's disease among older African Americans living in the Chicago, IL, area. The study entails annual clinical evaluations, including measures of 19 neuropsychological tests that represent five cognitive domains, including episodic, semantic, and working memory, perceptual speed, and visuospatial ability.

PARTICIPANTS

Participants (n = 671; mean age = 73.5 years; standard deviation = 6.2 years) were included in the present analysis if they were dementia free at baseline and completed at least two clinical evaluations, on average 1 year apart, that included valid cognitive and BMI assessments.

RESULTS

Mixed-effects models showed higher baseline BMI was related to slower global cognitive decline, whereas changes in BMI (instability) were related to faster global cognitive decline. These effects were the same for four of five cognitive domains and remained after controlling for various health characteristics. However, women and men did not differ in any of the relationships.

CONCLUSION

Higher BMI is related to slower cognitive decline in older African Americans, but greater BMI instability is related to faster decline. Stability of BMI should be considered in the cognitive aging of African Americans.

The Potential Mediation of the Effects of Physical Activity on Cognitive Function by the Gut Microbiome

The population of older adults is growing dramatically worldwide. As older adults are at greater risk of developing disorders associated with cognitive dysfunction (i.e., dementia), healthcare costs are expected to double by 2040. Evidence suggests dementia may be slowed or prevented by lifestyle interventions, including physical activity (PA). PA is associated with improved cognitive function and may reduce risk for dementia by mitigating known risk factors (i.e., cardiovascular diseases) and/or by enhancing neurochemical processes. An emerging area of research suggests the gut microbiome may have similar neuroprotective effects. Altering the gut microbiome has been found to target physiological processes associated with dementia risk, and it influences gut-brain-microbiome axis signaling, impacting cognitive functioning. The gut microbiome can be altered by several means (i.e., disease, diet, prebiotics, probiotics), including PA. As PA and the gut microbiome independently influence cognitive function and PA changes the composition of the gut microbiome, cognitive improvement due to PA may be partially mediated by the gut microbiome. The present article provides an overview of the literature regarding the complex associations among PA, cognitive function, and the gut microbiome, as well as their underlying biological mechanisms. A comprehensive, theoretical model integrating evidence for the potential mediation is proposed.

The Utilization of Complementary and Alternative Medicine among Saudi Older Adults: A Population-Based Study

BACKGROUND

Complementary and alternative medicine (CAM) is an integral part of patients' therapeutic experience worldwide. Among Saudi older adults, less is known about CAM utilization.

OBJECTIVES

To determine the prevalence, patterns, and factors associated with CAM utilization among SOA.

METHODS

In the Saudi National Survey for Elderly Health (SNSEH), subjects were asked about CAM use during the last twelve months before the interview. CAM use was defined as any use of herbal products, acupuncture, bloodletting, cauterization, medical massage, bones manual manipulation, honey, or religious rituals. Demographic characteristics included gender, age, marital status, region, educational level, and residence area. In addition, multiple comorbidities were included as possible factors that may be associated with CAM use. Multivariable logistic regression was used to explore factors associated with CAM utilization. All statistical analyses were done using STATA v.14.

RESULTS

Out of 2946 respondents, 50.4% were males, the mean age was 70.3 ± 8.3 years, and 70% were illiterate. CAM use was prevalent (62.5%). The most common CAM types were herbal products (25.4%), acupuncture (21.2%), bloodletting (12%), honey (9.5%), cauterization (7.4%), medical massage and bones manual manipulation (4%), and traditional bone setting (2.1%). In the multivariable regression, age, gender, and marital status did not have an impact on the odds of using CAM. Subjects from rural areas were 2.92 times more likely to use CAM compared with subjects in urban areas (OR = 2.92; 95%CI: 2.28-3.75). Subjects with metabolic disorders (OR = 0.50; 95% CI: 0.42-0.60) or kidney disease were less likely to use CAM (OR = 0.30; 95%CI: 0.14-0.64). About pain, CAM is used more in neck pain (OR = 1.69; 95%CI: 1.30-2.21) and also used in back pain (OR =  1.22; 95%CI: 1.03-1.46).

CONCLUSIONS

CAM use was very prevalent among SOA. Clinicians and pharmacists must ask about CAM use among older adults as many of CAM may interact with patients medications.

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.

Determinants of cognitive performance and decline in 20 diverse ethno-regional groups: A COSMIC collaboration cohort study

BACKGROUND

With no effective treatments for cognitive decline or dementia, improving the evidence base for modifiable risk factors is a research priority. This study investigated associations between risk factors and late-life cognitive decline on a global scale, including comparisons between ethno-regional groups.

METHODS AND FINDINGS

We harmonized longitudinal data from 20 population-based cohorts from 15 countries over 5 continents, including 48,522 individuals (58.4% women) aged 54-105 (mean = 72.7) years and without dementia at baseline. Studies had 2-15 years of follow-up. The risk factors investigated were age, sex, education, alcohol consumption, anxiety, apolipoprotein E ε4 allele (APOE*4) status, atrial fibrillation, blood pressure and pulse pressure, body mass index, cardiovascular disease, depression, diabetes, self-rated health, high cholesterol, hypertension, peripheral vascular disease, physical activity, smoking, and history of stroke. Associations with risk factors were determined for a global cognitive composite outcome (memory, language, processing speed, and executive functioning tests) and Mini-Mental State Examination score. Individual participant data meta-analyses of multivariable linear mixed model results pooled across cohorts revealed that for at least 1 cognitive outcome, age (B = -0.1, SE = 0.01), APOE*4 carriage (B = -0.31, SE = 0.11), depression (B = -0.11, SE = 0.06), diabetes (B = -0.23, SE = 0.10), current smoking (B = -0.20, SE = 0.08), and history of stroke (B = -0.22, SE = 0.09) were independently associated with poorer cognitive performance (p < 0.05 for all), and higher levels of education (B = 0.12, SE = 0.02) and vigorous physical activity (B = 0.17, SE = 0.06) were associated with better performance (p < 0.01 for both). Age (B = -0.07, SE = 0.01), APOE*4 carriage (B = -0.41, SE = 0.18), and diabetes (B = -0.18, SE = 0.10) were independently associated with faster cognitive decline (p < 0.05 for all). Different effects between Asian people and white people included stronger associations for Asian people between ever smoking and poorer cognition (group by risk factor interaction: B = -0.24, SE = 0.12), and between diabetes and cognitive decline (B = -0.66, SE = 0.27; p < 0.05 for both). Limitations of our study include a loss or distortion of risk factor data with harmonization, and not investigating factors at midlife.

CONCLUSIONS

These results suggest that education, smoking, physical activity, diabetes, and stroke are all modifiable factors associated with cognitive decline. If these factors are determined to be causal, controlling them could minimize worldwide levels of cognitive decline. However, any global prevention strategy may need to consider ethno-regional differences.

Precision Aging: Applying Precision Medicine to the Field of Cognitive Aging

The current "one size fits all" approach to our cognitive aging population is not adequate to close the gap between cognitive health span and lifespan. In this review article, we present a novel model for understanding, preventing, and treating age-related cognitive impairment (ARCI) based on concepts borrowed from precision medicine. We will discuss how multiple risk factors can be classified into risk categories because of their interrelatedness in real life, the genetic variants that increase sensitivity to, or ameliorate, risk for ARCI, and the brain drivers or common mechanisms mediating brain aging. Rather than providing a definitive model of risk for ARCI and cognitive decline, the Precision Aging model is meant as a starting point to guide future research. To that end, after briefly discussing key risk categories, genetic risks, and brain drivers, we conclude with a discussion of steps that must be taken to move the field forward.

Associations of the metabolic syndrome and its components with cognitive impairment in older adults

Background

The metabolic syndrome (MetS) is an established cardiovascular risk factor. Here, we investigated its role in cognitive impairment.

Methods

Baseline data from 202 participants (aged 65 to 87 years) of the BioCog study were used. All were free of clinical dementia (MMSE≥24/30). Cognitive impairment was defined as the lowest tertile of a cognitive summary score. Multiple logistic regression analyses examined associations of body mass index (BMI), triglycerides (TG), high-density lipoprotein (HDL-C), glucose and glycated hemoglobin A1c (HbA1c) levels with the odds of cognitive impairment. MetS was defined as ≥3 of its 5 components obesity (BMI ≥ 30 kg/m²), elevated TG (TG ≥1.7 mmol/L), reduced HDL-C (males: < 1.0 mmol/L; females: < 1.3 mmol/L), elevated glucose (glucose ≥5.5 mmol/L and/or diagnosed diabetes) and elevated blood pressure (history of hypertension). Analyses controlled for age, sex and smoking history.

Results

Lower HDL-C was significantly associated with a higher odds of cognitive impairment (OR 2.70 per 1 mmol/L reduction; 95% CI 1.25, 5.56; p = 0.011), whereas BMI, TG, glucose and HbA1c were not (all p > 0.05). Results for HDL-C were similar when HDL-C, glucose, BMI and TG were entered into a single model (OR 2.56 per 1 mmol/L reduction, 95% CI 1.09, 5.88, p = 0.031) and when cerebrovascular disease and coronary heart disease were additionally controlled for (OR 2.56 per 1 mmol/L reduction, 95% CI 1.06, 6.25, p = 0.036). Among the 5 MetS components, participants with elevated TG were at 2-fold increased odds of impairment (OR 2.09, 95% CI 1.08, 4.05, p = 0.028) including when the remaining 4 MetS components were entered (OR 2.23, 95% CI 1.07, 4.65, p = 0.033), but the finding was no longer statistically significant when cerebrovascular disease and coronary heart disease were additionally controlled for (p = 0.11). Presence of MetS and of obesity, reduced HDL-C, elevated glucose or elevated blood pressure were not significantly associated with impairment (all p > 0.05).

Conclusion

Our findings support low HDL-C as an independent risk marker of cognitive impairment in older age. The need for research into mediatory and confounding factors, and re-evaluation of traditional cut-off points is highlighted.

Trial registration

The study was registered on 15th October 2014 at clinicaltrials.gov (NCT02265263).

Relationship between adiposity parameters and cognition: the "fat and jolly" hypothesis in middle-aged and elderly people in China

The association between adiposity parameters and cognition is complex. The purpose of this study was to assess the relationship between adiposity parameters and cognition in middle-aged and elderly people in China.Data were obtained from a cross-sectional study. Cognitive function was evaluated in 5 domains, and adiposity parameters were measured. The association between adiposity parameters and cognition was analyzed using multiple linear and binary logistic regression analyses.After controlling for confounders, men with overweight and obesity had better scores in TICS-10 ([1] total, overweight vs normal: P = .006, β = 0.04; obesity vs normal: P = .005, β = 0.04. [2] stratification by age, with age ≥ 59 years, overweight vs normal: P = .006, β = 0.05; obesity vs normal: P = .014, β = 0.05. [3] stratification by educational levels, with less than elementary education, overweight vs normal: P = .011, β = 0.05; obesity vs normal: P = .005, β = 0.05), immediate word recall ([1] total, overweight vs normal: P = .015, β = 0.04. [2] stratification by age, with age 45-58 years, overweight vs normal: P = .036, β = 0.05. [3] stratification by educational levels, with less than elementary education, overweight vs normal: P = .044, β = 0.04; above high school, overweight vs normal: P = .041, β = 0.09), self-rated memory ([1] stratification by age, with age ≥ 59 years, overweight vs normal: P = .022, β = 0.05. [2] stratification by educational levels, with less than elementary education, overweight vs normal: P = .023, β = 0.04), and drawing a picture ([1] total, overweight vs normal: OR = 1.269, 95% CI = 1.05-1.53. [2] stratification by educational levels, with less than elementary education, overweight vs normal: OR = 1.312, 95% CI = 1.06-1.63); obesity vs normal: OR = 1.601, 95% CI = 1.11-2.31 than the normal weight; women with overweight and obesity had better measure scores in the TICS-10 ([1] total, overweight vs normal: P < .0001, β = 0.06; obesity vs normal: P < .0001, β = 0.05. [2] stratification by age, with age 45-58 years, obesity vs normal: P = .007, β = 0.05; with age ≥ 59 years: overweight vs normal: P < .0001, β = 0.07, obesity vs normal: P = .002, β = 0.06. [3] stratification by educational levels, with illiterate, overweight vs normal: P = .001, β = 0.08; obesity vs normal: P = .004, β = 0.06; with less than elementary education, overweight vs normal: P < .0001, β = 0.07; obesity vs normal: P = .010, β = 0.05), immediate word recall ([1] total, overweight vs normal: P = .011, β = 0.04; obesity vs normal: P = .002, β = 0.04. [2] stratification by age, with age 45-58 years, obesity vs normal: P = .021, β = 0.05; with age ≥ 59 years: overweight vs normal: P = .003, β = 0.06. [3] stratification by educational levels, with illiterate, obesity vs normal: P = .028, β = 0.05; with less than elementary education, obesity vs normal: P = .016, β = 0.05), delay word recall ([1] total, overweight vs normal: P = .015, β = 0.03; obesity vs normal: P = .031, β = 0.03. [2] stratification by age, with age ≥ 59 years: overweight vs normal: P = .004, β = 0.06. [3] stratification by educational levels, with less than elementary education, obesity vs normal: P = .043, β = 0.04), self-rated memory ([1] total, obesity vs normal: P = .026, β = 0.03. [2] stratification by age, with age ≥ 59 years, overweight vs normal: P = .044, β = 0.04; obesity vs normal: P = .018, β = 0.05), and drawing a picture ([1] total, overweight vs normal: OR = 1.226, 95% CI = 1.06-1.42. [2] stratification by age, with age 45-58 years: overweight vs normal: OR = 1.246, 95% CI = 1.02-1.53) than the normal weight. Regarding the association between WC and cognitive function, the obesity demonstrated better mental capacity ([1] total, men: P < .0001, β = 0.06; women: P < .0001, β = 0.05. [2] stratification by age, men with age 45-58 years: P < .0001, β = 0.08; men with ≥ 59 years: P = .006, β = 0.05. women with age 45-58 years: P = .001, β = 0.06; women with ≥ 59 years: P = .012, β = 0.04. [3] stratification by educational levels, men with illiterate: P = .045, β = 0.09; men with less than elementary education: P < .0001, β = 0.08; women with illiterate: P < .0001, β = 0.09), ability to recall immediately ([1] total, men: P = .030, β = 0.03; women: P = .001, β = 0.05. [2] stratification by age, women with age 45-58 years: P = .028, β = 0.04; women with ≥ 59 years: P = .007, β = 0.05. [3] stratification by educational levels, men with less than elementary education: P = .007, β = 0.05; women with illiterate: P = .027, β = 0.05; women with less than elementary education: P = .002, β = 0.06), delay word recall ([1] total, women: P = .044, β = 0.03. [2] stratification by educational levels, men with less than elementary education: P = .023, β = 0.04), self-rated memory (stratification by educational levels, women with less than elementary education: P = .030, β = 0.04), and draw a picture ([1] total, men: OR = 1.399, 95% CI = 1.17-1.67; women: OR = 1.273, 95% CI = 1.12-1.45. [2] stratification by age, men with age 45-58 years: OR = 1.527, 95% CI = 1.15-2.03; men with age ≥ 59 years: OR = 1.284, 95% CI = 1.02-1.61; women with age 45-58 years: OR = 1.320, 95% CI = 1.10-1.58; women with age ≥ 59 years: OR = 1.223, 95% CI = 1.01-1.49. [3] stratification by educational levels, men with less than elementary education: OR = 1.528, 95% CI = 1.25-1.87; women with illiterate: OR = 1.404, 95% CI = 1.14-1.73) than the participants with normal weight after the multivariate adjustment.Our study demonstrated a significant relationship between adiposity parameters and cognition that supports the "jolly fat" hypothesis.

Body mass index, waist-to-hip ratio and cognitive function among Chinese elderly: a cross-sectional study

OBJECTIVES

To investigate the associations between body mass index (BMI), waist-to-hip ratio (WHR) and cognitive function among Chinese elderly.

DESIGN

Cross-sectional study.

SETTING

Community.

PARTICIPANTS

Data were obtained from the baseline survey of a community-based cohort in Zhejiang Province, and 9326 persons aged 60 years and older were enrolled.

PRIMARY OUTCOME MEASURES

We investigated the association between BMI and cognition, and then explored the association between WHR and cognition across different quartiles of BMI.

RESULTS

A sample of 9087 persons was used in this study, including 4375 men and 4712 women. Higher WHR increased cognitive impairment risk in those with BMI >25.3 kg/m² (OR (per 0.1 increase) 1.39; 95% CI 1.13 to 1.70). No statistically significant association was found in other BMI categories.

CONCLUSIONS

Higher WHR could increase the risk of cognitive impairment among elderly with BMI >25.3 kg/m². Our results suggest that it could be of benefit to the elderly with high BMI to control WHR.

Sarcopenic obesity and cognitive performance

BACKGROUND

Sarcopenia and obesity both negatively impact health including cognitive function. Their coexistence, however, can pose an even higher threat likely surpassing their individual effects. We assessed the relationship of sarcopenic obesity with performance on global- and subdomain-specific tests of cognition.

PATIENTS AND METHODS

The study was a cross-sectional analysis of data from a series of community-based aging and memory studies. The sample consisted of a total of 353 participants with an average age of 69 years with a clinic visit and valid cognitive (eg, Montreal Cognitive Assessment, animal naming), functional (eg, grip strength, chair stands), and body composition (eg, muscle mass, body mass index, percent body fat) measurements.

RESULTS

Sarcopenic obesity was associated with the lowest performance on global cognition (Est.Definition1=-2.85±1.38, p=0.039), followed by sarcopenia (Est.Definition1=-1.88±0.79, p=0.017) and obesity (Est.Definition1=-1.10±0.81, p=0.175) adjusted for sociodemographic factors. The latter, however, did not differ significantly from the comparison group consisting of older adults with neither sarcopenia nor obesity. Subdomain-specific analyses revealed executive function (Est.Definition1=-1.22±0.46 for sarcopenic obesity; Est.Definition1=-0.76±0.26 for sarcopenia; Est.Definition1=-0.52±0.27 for obesity all at p<0.05) and orientation (Est.Definition1=0.59±0.26 for sarcopenic obesity; Est.Definition1=-0.36±0.15 for sarcopenia; Est.Definition1=-0.29±0.15 all but obesity significant at p<0.05) as the individual cognitive skills likely to be impacted. Potential age-specific and depression effects are discussed.

CONCLUSION

Sarcopenia alone and in combination with sarcopenic obesity can be used in clinical practice as indicators of probable cognitive impairment. At-risk older adults may benefit from programs addressing loss of cognitive function by maintaining/improving strength and preventing obesity.

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

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 (β = 0.208, p = .026, ΔR² = 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.

Risk factors for crash involvement in older motorcycle riders

A prospective cohort study was conducted to identify risk and protective factors for crash involvement in older motorcyclists. Over a 1-year study period from August 2013 to July 2014, study participants were recruited from local community centers of five cities in Taiwan. People aged ≥60 years who rode a motorcycle at least once per week were eligible and were invited to participate in the study. Among 256 older riders who completed the baseline assessment and at least one of the four follow-up assessments, 79 (33.7%) experienced a motorcycle crash over the study period. Results of the proportional hazards model showed that after controlling for age, gender, and riding distance, older riders who had sustained hearing impairment (hazard ratio (HR)=2.58; 95% confidence interval (CI), 1.30-5.15), rode a motorcycle at speeds of ≥41km/h (HR=2.31; 95% CI, 1.26-4.23), and had experienced a motorcycle crash in the past year (HR=1.81; 95% CI, 1.06-3.09) were more likely to be involved in a crash, compared to their counterparts. Conversely, older riders who were obese (HR=0.43; 95% CI, 0.22-0.82) were less likely to be involved in a crash than those with a normal weight, while longer functional reach distances (HR=0.96; 95% CI, 0.93-0.99) and higher Tinetti balance scores (HR=0.79; 95% CI, 0.69-0.91) were associated with a reduced risk of crash involvement. Among older people riding a motorcycle as their primary source of transportation, several factors associated with the occurrence of motorcycle crashes were identified. Restrictions and modifications of these risk factors may help design effective safety interventions for reducing crash and injury risks of this increasing riding population.

Insulin Resistance is Associated with Cognitive Decline Among Older Koreans with Normal Baseline Cognitive Function: A Prospective Community-Based Cohort Study

We evaluated whether metabolic factors were associated with cognitive decline, compared to baseline cognitive function, among geriatric population. The present study evaluated data from an ongoing prospective community-based Korean cohort study. Among 1,387 participants who were >65 years old, 422 participants were evaluated using the Korean mini-mental status examination (K-MMSE) at the baseline and follow-up examinations. The mean age at the baseline was 69.3 ± 2.9 years, and 222 participants (52.6%) were men. The mean duration of education was 7.1 ± 3.6 years. During a mean follow-up of 5.9 ± 0.1 years, the K-MMSE score significantly decreased (−1.1 ± 2.7 scores), although no significant change was observed in the homeostasis model assessment of insulin resistance (HOMA-IR) value. Participants with more decreased percent changes in K-MMSE scores had a shorter duration of education (p = 0.001), older age (p = 0.022), higher baseline K-MMSE score (p < 0.001), and increased insulin resistance (∆HOMA-IR, p = 0.002). The correlation between the percent changes in K-MMSE and ∆HOMA-IR values remained significant after multivariable adjustment (B = −0.201, p = 0.002). During a 6-year follow-up of older Koreans with normal baseline cognitive function, increased insulin resistance was significantly correlated with decreased cognitive function.

Obesity and the burden of health risks among the elderly in Ghana: A population study

BACKGROUND

The causes and health risks associated with obesity in young people have been extensively documented, but elderly obesity is less well understood, especially in sub-Saharan Africa. This study examines the relationship between obesity and the risk of chronic diseases, cognitive impairment, and functional disability among the elderly in Ghana. It highlights the social and cultural dimensions of elderly obesity and discusses the implications of related health risks using a socio-ecological model.

METHODOLOGY

We used data from wave 1 of the Ghana Study on Global Ageing and Adult Health (SAGE) survey-2007/8, with a restricted sample of 2,091 for those 65 years and older. Using random effects multinomial, ordered, and binary logit models, we examined the relationship between obesity and the risk of stage 1 and stage 2 hypertension, arthritis, difficulties with recall and learning new tasks, and deficiencies with activities of daily living and instrumental activities of daily living.

FINDINGS

Elderly Ghanaians who were overweight and obese had a higher risk of stage 1 and stage 2 hypertension, and were more likely to be diagnosed with arthritis and report severe deficiencies with instrumental activities of daily living. Those who were underweight were 1.71 times more likely to report severe difficulties with activities of daily living. A sub analysis using waist circumference as a measure of body fat showed elderly females with abdominal adiposity were relatively more likely to have stage 2 hypertension.

CONCLUSIONS

These findings call for urgent policy initiatives geared towards reducing obesity among working adults given the potentially detrimental consequences in late adulthood. Future research should explore the gendered pathways leading to health disadvantages among Ghanaian women in late adulthood.

Higher Adiposity Is Associated With Slower Cognitive Decline in Hypertensive Patients: Secondary Analysis of the China Stroke Primary Prevention Trial

BACKGROUND

Obesity is a risk factor for many diseases. However, the potential association between adiposity and cognitive decline in hypertensive patients is inconclusive. We performed a secondary data analysis of the CSPPT (China Stroke Primary Prevention Trial) to examine whether adiposity is correlated with longitudinal cognitive performance in hypertensive adults.

METHODS AND RESULTS

The analysis included 16 791 patients in the CSPPT who received at least 2 cognitive assessments by the Mini-Mental State Examination (MMSE) during the follow-up (median, 4.5 years; interquartile range, 4.2-4.8 years). Outcomes included changes in MMSE scores and cognitive impairment (defined as MMSE score less than education-specific cutoff point). A marked reduction in MMSE scores at the final (compared with at the 1-year) follow-up was apparent in both men (n=4838; mean [SD] score, 0.41 [3.62]) and women (n=7190; mean [SD] score, 1.07 [4.61]; both P<0.001). Analysis using a mixed-effects model revealed an association between higher body mass index with less MMSE decline, even after controlling for demographics and comorbidities (men, β=0.0134 [SE, 0.0036]; women, β=0.0133 [SE, 0.0034]; both P<0.001). A total of 1037 men (15.3%) and 3317 women (33.1%) developed cognitive impairment. In multivariable Cox regression analyses, being obese in men (11.3% versus 18.0%; hazard ratio, 0.75; 95% confidence interval, 0.60-0.94) and women (30.1% versus 36.5%; hazard ratio, 0.82; 95% confidence interval, 0.74-0.91) was a protective factor against cognitive impairment compared with normal body mass index.

CONCLUSIONS

Higher adiposity is independently associated with slower cognitive decline in Chinese hypertensive adults.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794885 CSPPT.

Body mass index, inflammatory biomarkers and neurocognitive impairment in HIV-infected persons

To determine the relationships among body mass index (BMI), and HIV-associated neurocognitive impairment and the potential mediating effects of inflammatory cytokines. Among the HIV-infected individuals (N = 90) included in this study, obesity was associated with slower processing speed (β = -.229, standard error (SE) = 2.15, p = .033), compared to participants with a normal BMI, after controlling for psychosocial and HIV clinical factors. Serum concentrations of the interleukin-16 (IL-16) cytokine were significantly associated with slowed processing speed (β = -.235, SE = 1.62, p = .033) but did not mediate the relationship between obesity and processing speed These findings suggest that obesity may contribute to cognitive processing speed deficits in HIV-infected adults. Elevated concentrations of IL-16 are also associated with slowing, though the results suggest that obesity and IL-16 may exert independent effects.

Obesity and brain illness: from cognitive and psychological evidences to obesity paradox

Recent findings showed that obesity represents an additional risk factor to developing brain illness such as cognitive impairments and psychopathological disorders. However, some benefits of overweight in the elderly have been identified and an "obesity paradox" has been shown. Currently, it is still unknown how obesity and brain functioning could be linked, and the process by which body fat independently injures cognitive abilities and psychological well-being remains unclear. To establish the independent role of obesity on cognitive abilities and mental health, clarifying the role played by several factors and understanding their interaction is essential. In this review, we discuss the relationship between obesity and brain illness and underline the role played by confounders and other covariates to determine this link.

Decline in Weight and Incident Mild Cognitive Impairment: Mayo Clinic Study of Aging

IMPORTANCE

Unintentional weight loss has been associated with risk of dementia. Because mild cognitive impairment (MCI) is a prodromal stage for dementia, we sought to evaluate whether changes in weight and body mass index (BMI) may predict incident MCI.

OBJECTIVE

To investigate the association of change in weight and BMI with risk of MCI.

DESIGN, SETTING, AND PARTICIPANTS

A population-based, prospective study of participants 70 years of age or older from the Mayo Clinic Study of Aging, which was initiated on October 1, 2004. Maximum weight and height in midlife (40-65 years of age) were retrospectively ascertained from the medical records of participants using a medical records-linkage system. The statistical analyses were performed between January and November 2015.

MAIN OUTCOMES AND MEASURES

Participants were evaluated for cognitive outcomes of normal cognition, MCI, or dementia at baseline and prospectively assessed for incident events at each 15-month evaluation. The association of rate of change in weight and BMI with risk of MCI was investigated using proportional hazards models.

RESULTS

Over a mean follow-up of 4.4 years, 524 of 1895 cognitively normal participants developed incident MCI (50.3% were men; mean age, 78.5 years). The mean (SD) rate of weight change per decade from midlife to study entry was greater for participants who developed incident MCI vs those who remained cognitively normal (-2.0 [5.1] vs -1.2 [4.9] kg; P = .006). A greater decline in weight per decade was associated with an increased risk of incident MCI (hazard ratio [HR], 1.04 [95% CI, 1.02-1.06]; P < .001) after adjusting for sex, education, and apolipoprotein E (APOE) ε4 allele. A weight loss of 5 kg per decade corresponds to a 24% increase in risk of MCI (HR, 1.24). A higher decrease in BMI per decade was also associated with incident MCI (HR, 1.08 [95% CI, 1.03-1.13]; P = .003).

CONCLUSIONS AND RELEVANCE

These findings suggest that increasing weight loss per decade from midlife to late life is a marker for MCI and may help identify persons at increased risk for MCI.

Nonlinear associations between plasma cholesterol levels and neuropsychological function

OBJECTIVE

Although both high and low levels of total and low-density lipoprotein (LDL) cholesterol have been associated with poor neuropsychological function, little research has examined nonlinear effects. We examined quadratic relations of cholesterol to performance on a comprehensive neuropsychological battery.

METHOD

Participants were 190 older adults (53% men, ages 54-83) free of major medical, neurologic, and psychiatric disease. Measures of fasting plasma total and high-density lipoprotein (HDL) cholesterol were assayed, and LDL cholesterol was calculated. Participants completed neuropsychological measures of attention, executive function, memory, visuospatial judgment, and manual speed and dexterity. Multiple regression analyses examined cholesterol levels as quadratic predictors of each measure of cognitive performance, with age (dichotomized as <70 vs. 70+) as an effect modifier.

RESULTS

A significant quadratic effect of Total Cholesterol² × Age was identified for Logical Memory II (b = -.0013, p = .039), such that the 70+ group performed best at high and low levels of total cholesterol than at midrange total cholesterol (U-shaped) and the <70 group performed worse at high and low levels of total cholesterol than at midrange total cholesterol (inverted U shape). Similarly, significant U- and J-shaped effects of LDL Cholesterol² × Age were identified for Visual Reproduction II (b = -.0020, p = .026) and log of the Trail Making Test, Part B (b = .0001, p = .044). Quadratic associations between HDL cholesterol and cognitive performance were nonsignificant.

CONCLUSIONS

Results indicate differential associations between cholesterol and neuropsychological function across different ages and domains of function. High and low total and LDL cholesterol may confer both risk and benefit for suboptimal cognitive function at different ages. (PsycINFO Database Record

Muscle function and fat content in relation to sarcopenia, obesity and frailty of old age--An overview

BACKGROUND AND AIM

In western countries, the proportion of people over age 60 is increasing faster than any other group. This is linked to higher rates of obesity. Older age, co-morbidities and obesity are all associated with frailty syndrome. In the core of both frailty and sarcopenia there are dysfunction and deterioration of the muscle and the fat tissues. This overview interlinks the phenotypes presented in older adults such as sarcopenia and frailty-alone and with relation to obesity, muscle function and fat tissue accumulation.

RECENT FINDINGS

Observational studies have well described the loss of muscle mass and strength through the years of adult life, both components of frailty and sarcopenia. They have shown that these changes are associated with dysmetabolism and functional deterioration, independent of common explanatory variables. In the metabolic mechanism core of this link, insulin resistance and higher ectopic fat accumulation may play a role. Basic experiments have partially validated this hypothesis. Whether there is a synergistic effect of obesity and frailty phenotype on morbidity risk is still questionable and currently under investigation; however, few cohort studies have shown that the frail-obese or sarcopenic-obese group have higher probability for metabolic complications.

SUMMARY

Muscle mass loss and fat accumulation in the muscle in the elderly, with or without the presence of obesity, may explain some of the functional and metabolic defects shown in the frail, sarcopenic population.

Predictors of Long-Term Change in Adult Cognitive Performance: Systematic Review and Data from the Northern Finland Birth Cohort 1966

OBJECTIVE

Several social life events and challenges have an impact on cognitive development. Our goal was to analyze the predictors of change in cognitive performance in early midlife in a general population sample. Additionally, systematic literature review was performed.

METHOD

The study sample was drawn from the Northern Finland Birth Cohort 1966 at the ages of 34 and 43 years. Primary school performance, sociodemographic factors and body mass index (BMI) were used to predict change in cognitive performance measured by the California Verbal Learning Test, Visual Object Learning Test, and Abstraction Inhibition and Working Memory task. Analyses were weighted by gender and education, and p-values were corrected for multiple comparisons using Benjamini-Hochberg procedure (B-H).

RESULTS

Male gender predicted decrease in episodic memory. Poor school marks of practical subjects, having no children, and increase in BMI were associated with decrease in episodic memory, though non-significantly after B-H. Better school marks, and higher occupational class were associated with preserved performance in visual object learning. Higher vocational education predicted preserved performance in visual object learning test, though non-significantly after B-H. Likewise, having children predicted decreased performance in executive functioning but non-significantly after B-H.

CONCLUSIONS

Adolescent cognitive ability, change in BMI and several sociodemographic factors appear to predict cognitive changes in early midlife. The key advantage of present study is the exploration of possible predictors of change in cognitive performance among general population in the early midlife, a developmental period that has been earlier overlooked.

Retirement and cognitive development in the Netherlands: Are the retired really inactive?

This paper uses longitudinal data to analyze the relation between retirement and cognitive development in the Netherlands. Controlling for individual fixed effects and lagged cognition, we find that retirees face lower declines in their cognitive flexibility than those who remain employed, which appears to be persistent 6 years after retirement. However, the information processing speed of low-educated retirees declines faster. The magnitude of both changes in cognition is such that retirees appear 5-6 years younger in terms of cognitive flexibility, and older in terms of information processing speed. We show that these relationships between retirement and cognitive development cannot be explained by (1) feeling relieved from routine work, (2) changes in mood, (3) changes in lifestyle, and (4) changes in blood pressure. The decline in information processing speed after retirement particularly holds for the low educated. This could increase the social costs of an aging society.

Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions

It is of vital importance to understand how the foods which are making us fat also act to impair cognition. In this review, we compare the effects of acute and chronic exposure to high-energy diets on cognition and examine the relative contributions of fat (saturated and polyunsaturated) and sugar to these deficits. Hippocampal-dependent memory appears to be particularly vulnerable to the effects of high-energy diets and these deficits can occur rapidly and prior to weight gain. More chronic diet exposure seems necessary however to impair other sorts of memory. Many potential mechanisms have been proposed to underlie diet-induced cognitive decline and we will focus on inflammation and the neurotrophic factor, brain-derived neurotrophic factor (BDNF). Finally, given supplementation of diets with omega-3 and curcumin has been shown to have positive effects on cognitive function in healthy ageing humans and in disease states, we will discuss how these nutritional interventions may attenuate diet-induced cognitive decline. We hope this approach will provide important insights into the causes of diet-induced cognitive deficits, and inform the development of novel therapeutics to prevent or ameliorate such memory impairments.

Obesity and Aging: Consequences for Cognition, Brain Structure, and Brain Function

OBJECTIVES

This review focuses on the relationship between obesity and aging and how these interact to affect cognitive function. The topics covered are guided by the Scaffolding Theory of Aging and Cognition (STAC [Park and Reuter-Lorenz. Annu Rev Psychol 2009;60:173-96]-a conceptual model designed to relate brain structure and function to one's level of cognitive ability.

METHODS

The initial literature search was focused on normal aging and was guided by the key words, "aging, cognition, and obesity" in PubMed. In a second search, we added key words related to neuropathology including words "Alzheimer's disease," "vascular dementia," and "mild cognitive impairment."

RESULTS

The data suggest that being overweight or obese in midlife may be more detrimental to subsequent age-related cognitive decline than being overweight or obese at later stages of the life span. These effects are likely mediated by the accelerated effects obesity has on the integrity of neural structures, including both gray and white matter. Further epidemiological studies have provided evidence that obesity in midlife is linked to an increased risk for Alzheimer's disease and vascular dementia, most likely via an increased accumulation of Alzheimer's disease pathology.

CONCLUSIONS

Although it is clear that obesity negatively affects cognition, more work is needed to better understand how aging plays a role and how brain structure and brain function might mediate the relationship of obesity and age on cognition. Guided by the STAC and the STAC-R models, we provide a roadmap for future investigations of the role of obesity on cognition across the life span.

Rate of Cognitive Decline Before and After the Onset of Functional Limitations in Older Persons

BACKGROUND

Loss in physical function is indicative of deterioration in physiological health that may also be associated with deterioration in neurological health. The objective of this study was to examine whether the onset of functional limitations and their severity is associated with increases in cognitive decline among older adults.

METHODS

The study sample consists of 3825 (65% African Americans and 53% females) participants over the age of 65 with no functional limitations. Cognitive function was assessed using a standardized global cognitive score, and functional limitations using a summary measure of 8 Rosow-Breslau and Nagi limitations (ROS-B/Nagi). Cognitive decline before and after the onset of limitations were analyzed using a linear piecewise change point model.

RESULTS

During follow-up, 2682 (70%) participants reported limitations in ROS-B/Nagi measure. The rate of cognitive decline was 0.053-units per year before any limitations, and increased to 0.069-units per year after one or more limitations in ROS-B/Nagi measure. This was about 30% (95% Confidence Interval [CI]: 18 - 42%) increase in the rate of cognitive decline comparing before and after the onset of limitations in ROS-B/Nagi measure. Also, higher number of limitations in ROS-B/Nagi measure at the time of onset was associated with faster cognitive decline.

CONCLUSIONS

The rate of cognitive decline was significantly higher following functional limitations. This study suggests that self-reported measures of functional limitations may serve as an important marker of cognitive decline.

Gene-environment interaction of body mass index and apolipoprotein E ε4 allele on cognitive decline

Genetic variation alone may not account for common chronic disease susceptibility. Rather, an interaction between genetic and environmental factors may clarify the underlying disease mechanism. Hence, we tested whether body mass index (BMI) modified the genetic association of the apolipoprotein E ε4 allele with cognitive decline. The data came from a longitudinal population-based sample of 4055 participants interviewed at 3-year intervals from 1993 to 2012. Cognitive function was assessed using a standardized global cognitive score and BMI was assessed at baseline and classified as normal, overweight, and obese. There were 1374 (34%) participants with the ε4 allele. In normal BMI participants, cognitive decline was 0.048 units/y without the ε4 allele, and increased by an additional 0.031 units/y with the ε4 allele. In overweight participants, cognitive decline was 0.038 units/y without the ε4 allele, and increased by an additional 0.026 units/y with the ε4 allele. Finally, in obese participants, cognitive decline was 0.038 units/y without the ε4 allele, and increased by an additional 0.014 units/y with the ε4 allele. The association of ε4 allele with cognitive decline was significantly lower in obese participants compared with normal BMI participants (P=0.003), thereby suggesting significant gene-environment interaction on cognitive decline.

Physical activity, body mass index, and brain atrophy in Alzheimer's disease

The purpose of this study was to use a novel imaging biomarker to assess associations between physical activity (PA), body mass index (BMI), and brain structure in normal aging, mild cognitive impairment, and Alzheimer's dementia. We studied 963 participants (mean age: 74.1 ± 4.4 years) from the multisite Cardiovascular Health Study including healthy controls (n = 724), Alzheimer's dementia patients (n = 104), and people with mild cognitive impairment (n = 135). Volumetric brain images were processed using tensor-based morphometry to analyze regional brain volumes. We regressed the local brain tissue volume on reported PA and computed BMI, and performed conjunction analyses using both variables. Covariates included age, sex, and study site. PA was independently associated with greater whole brain and regional brain volumes and reduced ventricular dilation. People with higher BMI had lower whole brain and regional brain volumes. A PA-BMI conjunction analysis showed brain preservation with PA and volume loss with increased BMI in overlapping brain regions. In one of the largest voxel-based cross-sectional studies to date, PA and lower BMI may be beneficial to the brain across the spectrum of aging and neurodegeneration.

Genetic variation at the CELF1 (CUGBP, elav-like family member 1 gene) locus is genome-wide associated with Alzheimer's disease and obesity

Deviations from normal body weight are observed prior to and after the onset of Alzheimer's disease (AD). Midlife obesity confers increased AD risk in later life, whereas late-life obesity is associated with decreased AD risk. The role of underweight and weight loss for AD risk is controversial. Based on the hypothesis of shared genetic variants for both obesity and AD, we analyzed the variants identified for AD or obesity from genome-wide association meta-analyses of the GERAD (AD, cases = 6,688, controls = 13,685) and GIANT (body mass index [BMI] as measure of obesity, n = 123,865) consortia. Our cross-disorder analysis of genome-wide significant 39 obesity SNPs and 23 AD SNPs in these two large data sets revealed that: (1) The AD SNP rs10838725 (pAD  = 1.1 × 10(-08)) at the locus CELF1 is also genome-wide significant for obesity (pBMI  = 7.35 × 10(-09) ). (2) Four additional AD risk SNPs were nominally associated with obesity (rs17125944 at FERMT2, pBMI  = 4.03 × 10(-05), pBMI corr  = 2.50 × 10(-03) ; rs3851179 at PICALM; pBMI  = 0.002, rs2075650 at TOMM40/APOE, pBMI  = 0.024, rs3865444 at CD33, pBMI  = 0.024). (3) SNPs at two of the obesity risk loci (rs4836133 downstream of ZNF608; pAD  = 0.002 and at rs713586 downstream of RBJ/DNAJC27; pAD  = 0.018) were nominally associated with AD risk. Additionally, among the SNPs used for confirmation in both studies the AD risk allele of rs1858973, with an AD association just below genome-wide significance (pAD  = 7.20 × 10(-07)), was also associated with obesity (SNP at IQCK/GPRC5B; pBMI  = 5.21 × 10(-06) ; pcorr  = 3.24 × 10(-04)). Our first GWAS based cross-disorder analysis for AD and obesity suggests that rs10838725 at the locus CELF1 might be relevant for both disorders.

Perceived stress and change in cognitive function among adults 65 years and older

OBJECTIVE

Exposure to acute and chronic stress can affect learning and memory, but most evidence comes from animal studies or clinical observations. Almost no population-based studies have investigated the relation of stress to cognition or changes in cognition over time. We examined whether higher levels of perceived stress were associated with accelerated decline in cognitive function in older blacks and whites from a community-based population sample.

METHODS

Participants included 6207 black and white adults (65.7% black, 63.3% women) from the Chicago Health and Aging Project. Two to five in-home assessments were completed over an average of 6.8 years of follow-up and included sociodemographics, health behaviors, psychosocial measures, cognitive function tests, and health history. Perceived stress was measured by a six-item scale, and a composite measure of four tests of cognition was used to determine cognitive function at each assessment.

RESULTS

Mixed-effects regression models showed that increasing levels of perceived stress were related to lower initial cognitive scores (B = -0.0379, standard error = 0.0025, p < .001) and a faster rate of cognitive decline (stress × time interaction: B = -0.0015, standard error = 0.0004, p < .001). Results were similar after adjusting for demographic variables, smoking, systolic blood pressure, body mass index, chronic medical conditions, and psychosocial factors and did not vary by race, sex, age, or education.

CONCLUSIONS

Increasing levels of stress are independently associated with accelerated declines in cognitive function in black and white adults 65 years and older.

Nonlinear longitudinal trajectories of cholesterol and neuropsychological function

OBJECTIVE

Prior literature has identified inconsistent longitudinal associations between total cholesterol and cognitive decline. The authors examined prospective nonlinear relations of coincident trajectories of total cholesterol and cognitive function among persons free of stroke, dementia, and other neurological disease.

METHOD

Up to 1,601 participants from the Baltimore Longitudinal Study of Aging (aged 19-93, 51% male, 75% White) underwent fasting cholesterol measurement and neuropsychological assessment on up to 12 occasions (M = 3.2, SD = 2.1) over up to 19 years (M = 6.4, SD = 5.3) of follow-up. Mixed-effects regression analyses were adjusted for age, sex, race, education, systolic blood pressure, body mass index, cardiovascular disease, lipid-lowering medication use, smoking, alcohol use, and depressive symptoms.

RESULTS

Analyses revealed significant longitudinal associations between quadratic total cholesterol and performance on measures of global mental status, verbal learning, executive function, and language (all ps < .05). In general, higher total cholesterol was associated with poorer middle-aged or young-old (60-69 years) cognitive performance, but better old-old (80-89 years) cognitive performance. Linear models also revealed an association between lower total cholesterol and accelerated decline in visual memory performance.

CONCLUSIONS

Overall, results indicate nonlinear longitudinal relations of total cholesterol to cognitive decline. Whereas higher cholesterol levels were associated with cognitive decline in the middle-aged or young-old, lower cholesterol levels were related to cognitive decline among old-old participants.

The emerging role of dietary fructose in obesity and cognitive decline

The incidence of obesity has increased dramatically over the past several years, and in parallel, so has the prevalence of type 2 diabetes (T2D). Numerous studies have demonstrated that both obesity and T2D are associated with lower cognitive performance, cognitive decline, and dementia. Intake of dietary fructose has also increased. In fact, high-fructose corn syrup (HFCS) accounts for as much as 40% of caloric sweeteners used in the United States. Given the increase in the incidence of Alzheimer’s disease (AD), characterized by an age-related decline in memory and cognitive functioning, in this report we review the effects of obesity on cognitive performance and the impact of high fructose intake in promoting cognitive decline. The paper then considers the effects of omega-3 fatty acids (FAs), which have been linked to promising results in cognitive function including ameliorating the impact of a high-fructose diet.

Nutrition and neurodegeneration: epidemiological evidence and challenges for future research

The prevention of dementias, such as Alzheimer's disease (AD), is a growing public health concern, due to a lack of effective curative treatment options and a rising global prevalence. Various potential risk or preventive factors have been suggested by epidemiological research, including modifiable lifestyle factors such as diet. Current epidemiological data are in favour of a protective role of certain micronutrients (B vitamins related to homocysteine metabolism, the anti-oxidant vitamins C and E, flavonoids, polyunsatured omega-3 fatty acids, vitamin D) and macronutrients (fish) in the prevention of cognitive decline and dementia/AD. Some factors have been targeted by interventions tested in randomized controlled trials (RCTs), but many of the results are conflicting with observational evidence. Epidemiological analysis of the relations between nutrient consumption and cognitive decline is complex and it is highly unlikely that a single component plays a major role. In addition, since multiple factors across the life course influence brain function in late life, multidomain interventions might be more promising in the prevention of cognitive decline and dementia/AD. Designing such trials remains very challenging for researchers. The main objective of this paper is to review the epidemiologic data linking potential protective factors to cognitive decline or dementia/AD, focusing particularly on the roles of adiposity, caloric restriction, micro (group B vitamins related to homocysteine metabolism, the anti-oxidant vitamins C and E, flavonoids, polyunsatured omega-3 fatty acids, vitamin D) and macronutrients (fish). Limitations of the current data, divergence with results of interventional prevention studies and challenges for future research are discussed.

Trajectory classes of body mass index in a representative elderly community sample

BACKGROUND

It is unclear whether distinct weight-related trajectory classes, differing in course, demographics, and health characteristics, exist in the elderly population.

METHODS

Data came from the 10-year (1986-1996) Duke Established Populations for Epidemiologic Studies of the Elderly study of 3,861 black (54%) and white (46%) participants aged 65-105 years. Latent-class trajectories of body mass index (BMI: kg/m(2)) based on self-reported weight and height at baseline, 3, 6, and 10 years later were determined using generalized mixture models. Polytomous logistic regression was used to identify baseline demographic and health characteristics that distinguished the trajectories, and 10-year postbaseline data to confirm the findings.

RESULTS

We identified three trajectories: normal weight (BMI ~24, 27.6% of the sample), overweight (BMI ~26, 65.1%), and obese (BMI ~31, 7.3%). Demographic characteristics distinguished the three trajectories: highest odds of blacks, women, and less education in the obese trajectory, lowest in the normal-weight trajectory. Obese and overweight differed adversely from normal-weight trajectories, but not significantly from each other on cognitive impairment, hypertension, and diabetes. Depressive symptomatology was more prevalent in the obese; they were also younger. There was no association with cancer or heart disease.

CONCLUSION

Distinct trajectories and course of BMI were present in this older population. Weight loss increased with increase in BMI class. Although demographic characteristics distinguished all trajectory classes, adverse health characteristics distinguished the overweight and obese classes from the normal-weight class, but not from each other. Problems associated with education and health are present at study entry and should be addressed earlier in life.

Effects of early-life adversity on cognitive decline in older African Americans and whites

OBJECTIVES

Early-life adversity is related to adult health in old age but little is known about its relation with cognitive decline.

METHODS

Participants included more than 6,100 older residents (mean age = 74.9 [7.1] years; 61.8% African American) enrolled in the Chicago Health and Aging Project, a geographically defined, population-based study of risk factors for Alzheimer disease. Participants were interviewed at approximately 3-year intervals for up to 16 years. The interview included a baseline evaluation of early-life adversity, and administration of 4 brief cognitive function tests to assess change in cognitive function. We estimated the relation of early-life adversity to rate of cognitive decline in a series of mixed-effects models.

RESULTS

In models stratified by race, and adjusted for age and sex, early-life adversity was differentially related to decline in African Americans and whites. Whereas no measure of early-life adversity related to cognitive decline in whites, both food deprivation and being thinner than average in early life were associated with a slower rate of cognitive decline in African Americans. The relations were not mediated by years of education and persisted after adjustment for cardiovascular factors.

CONCLUSIONS

Markers of early-life adversity had an unexpected protective effect on cognitive decline in African Americans.