Insulin-resistance and metabolic syndrome are related to executive function in women in a large family-based study

Sex Disparity in the Association of Metabolic Syndrome with Cognitive Impairment

Background/Objectives: Metabolic syndrome (MS) is a constellation of several cardiometabolic risk factors. We investigated sex disparity in the associations between MS and cognitive impairment using cross-sectional data from Taiwan Biobank. Methods: We determined the associations of MS and its five components with cognitive impairment (mini-mental state examination, MMSE < 24) and the five domains of MMSE using logistic regression analyses. Results: A total of 7399 men and 11,546 women were included, and MS was significantly associated with cognitive impairment only in women (adjusted OR 1.48, 95% CI 1.29-1.71, p = 0.001) (p for interaction 0.005). In women, the association with MS was significant in orientation (adjusted OR 1.21, 95% CI 1.07-1.37, p = 0.003), memory (adjusted OR 1.12, 95% CI 1.01-1.25, p = 0.034) and design copying (adjusted OR 1.41, 95% CI 1.23-1.62, p = 0.001) (p value for interaction 0.039, 0.023, and 0.093, respectively). Among the components of MS, a large waist circumference (adjusted OR 1.25, 95% CI 1.08-1.46, p = 0.003), high fasting glucose (adjusted OR 1.16, 95% CI 1.00-1.34, p = 0.046), and low HDL cholesterol (adjusted OR 1.16, 95% CI 1.00-1.34, p = 0.049) were significantly associated with cognitive impairment in women. Conclusions: Our findings suggest that sex has a significant influence on the association between MS and cognitive dysfunction, especially in orientation and memory.

Appetite hormone dysregulation and executive dysfunction among adolescents with bipolar disorder and disruptive mood dysregulation disorder

Appetite hormone dysregulation may play a role in the pathomechanisms of bipolar disorder and chronic irritability. However, its association with executive dysfunction in adolescents with bipolar disorder and those with disruptive mood dysregulation disorder (DMDD) remains unclear. We included 20 adolescents with bipolar disorder, 20 adolescents with DMDD, and 47 healthy controls. Fasting serum levels of appetite hormones, including leptin, ghrelin, insulin, and adiponectin were examined. All participants completed the Wisconsin Card Sorting Test. Generalized linear models with adjustments for age, sex, body mass index, and clinical symptoms revealed that patients with DMDD had elevated fasting log-transformed insulin levels (p = .023) compared to the control group. Adolescents with DMDD performed worse in terms of the number of tries required to complete tasks associated with the first category (p = .035), and adolescents with bipolar disorder performed worse in terms of the number of categories completed (p = .035). A positive correlation was observed between log-transformed insulin levels and the number of tries required for the first category (β = 1.847, p = .032). Adolescents with DMDD, but not those with bipolar disorder, were more likely to exhibit appetite hormone dysregulation compared to healthy controls. Increased insulin levels were also related to executive dysfunction in these patients. Prospective studies should elucidate the temporal association between appetite hormone dysregulation, executive dysfunction, and emotional dysregulation.

Effects of combined dietary intervention and physical-cognitive exercise on cognitive function and cardiometabolic health of postmenopausal women with obesity: a randomized controlled trial

BACKGROUND

Postmenopausal women with obesity are markedly at risk of cognitive impairment and several health issues. Emerging evidence demonstrated that both diet and exercise, particularly physical-cognitive exercise are involved in cognitive and health benefits. However, the comparative effect of diet, exercise, and combined interventions in postmenopausal women with obesity on cognition and cardiometabolic health is still lacking. Identifying the effective health promotion program and understanding changes in cardiometabolic health linking these interventions to cognition would have important medical implications. This RCT aimed to examine the effect of single and combined interventions of diet and exercise on cognitive function and cardiometabolic health in postmenopausal women with obesity.

METHODS

Ninety-two postmenopausal women with obesity were randomly assigned to diet group (intermittent fasting 2 days/week, 3 months), exercise group (physical-cognitive exercise 3 days/week, 3 months), combined group, or control group (n = 23/group). All cognitive outcomes and cardiometabolic outcomes were measured at baseline and post-3 months. Primary outcomes were executive functions, memory, and plasma BDNF levels. Secondary outcomes were global cognition, attention, language domain, plasma adiponectin levels, IL-6 levels, metabolic parameters, and physical function.

RESULTS

At the end of the 3-month intervention, the exercise and combined group demonstrated significant memory improvement which was accompanied by significant improvements in plasma BDNF level, insulin levels, HOMA-IR, %body fat, and muscle strength when compared to controls (p < 0.05). Only the combined intervention group demonstrated a significant improvement in executive function and increased plasma adiponectin levels when compared to control (p < 0.05). Surprisingly, no cognitive improvement was observed in the diet group (p > 0.05). Significant reduction in cholesterol levels was shown in the diet and combined groups when compared to controls (p < 0.05). Among the three intervention groups, there were no significant differences in all cognitive outcomes and cardiometabolic outcomes (p > 0.05). However, all three intervention groups showed significant improvements in plasma BDNF levels, weight, BMI, WHR, fat mass, and predicted VO2 max, when compared to control (p < 0.05).

CONCLUSION

These findings suggest that combined physical-cognitive exercise and dietary intervention are promising interventions to improve cognition and obesity-related complications of postmenopausal women with obesity.

TRIAL REGISTRATION

NCT04768725 ( https://clinicaltrials.gov ) 24th February 2021.

Association Between Metabolic Risk Factors and Cognitive Impairment in Schizophrenia Based on Sex

OBJECTIVE

Sex differences have been observed in many aspects of schizophrenia, including cognitive deficits. Despite extensive research into the relationship between metabolic factors and cognitive deficits in schizophrenia, few studies have explored the potential sex difference in their association.

METHODS

We recruited 358 schizophrenia patients and 231 healthy controls. The participants underwent measurements of body mass index (BMI), waist circumference, blood pressure, triglycerides, high-density lipoprotein cholesterol, and fasting blood glucose. Metabolic risk factors included abdominal obesity, hypertension, hyperglycemia, and dyslipidemia. A collection of these metabolic risk factors has been defined as metabolic syndrome. These diagnoses were based on the criteria of the National Cholesterol Education Program's Adult Treatment Panel III. Cognitive performance was measured using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). A descriptive analysis, difference analysis, and linear regression model were used to identify the metabolic risk factors for cognitive function in schizophrenia.

RESULTS

Our findings revealed sex differences in the rate of abdominal obesity and hypertension in schizophrenic patients. Additionally, we observed sex differences in the association between metabolic risk factors and cognitive impairment in schizophrenia. Specifically, hyperglycemia was associated with the immediate memory index score of RBANS in male patients, while dyslipidemia was associated with language, attention, delayed memory index scores, and RBANS total score in female patients.

CONCLUSION

Our results suggest that sex should be considered when evaluating the impact of metabolic disorders on the cognitive function of schizophrenic patients. Moreover, our study identifies hyperglycemia and dyslipidemia as potential targets for precise treatment by sex stratification, which could benefit the improvement of cognitive impairment in schizophrenic patients.

Metabolic syndrome and cognitive deficits in the Greek cohort of Epirus Health Study

BACKGROUND

Metabolic syndrome is considered an important risk factor for cognitive decline and dementia. However, the evidence in middle-aged individuals is still conflicting. The aim of the study was to explore the association between metabolic syndrome and its individual components with cognitive function and to investigate possible interaction between sex, age and genetic predisposition for metabolic syndrome and Alzheimer's disease in a middle-aged Greek cohort.

METHODS

A total of 2,077 healthy adults (mean age: 46.7 years) were included in the primary cross-sectional analysis and 305 of them in secondary prospective analyses. Metabolic syndrome was defined by the revised National Cholesterol Education-Adult Treatment Panel III and the International Diabetes Federation criteria. Cognitive function was measured primarily with the Trail Making, Verbal fluency and Logical Memory test, and in secondary prospective analyses with online versions of Posner cueing task, an emotional recognition task, Corsi block-tapping task and Stroop task.

RESULTS

Multivariable linear regressions showed an association of metabolic syndrome with lower performance in attention (β=1.62 seconds, 95% CI=0.20, 3.04) and memory (β=-0.62 words, 95% CI=-1.19, -0.05) that could be driven by associations with elevated fasting glucose and abdominal obesity. Similar associations were observed in the secondary prospective analyses.

CONCLUSION

In summary, metabolic syndrome was associated with cognitive deficits in domains related with the cognitive profile of vascular cognitive impairment.

The Triglyceride-Glucose Index Is Associated with Longitudinal Cognitive Decline in a Middle-Aged to Elderly Population: A Cohort Study

BACKGROUND

To examine the effect of the triglyceride-glucose (TyG) index on longitudinal cognitive decline in a healthy middle-aged-to-elderly population.

METHODS

We conducted a population-based longitudinal study. A total of 1774 participants without cognitive impairment were enrolled in the 4-year follow-up. They were divided into four groups according to the quartile of the TyG index. Multivariable-adjusted Cox proportional hazard models were performed to examine the association between the TyG index and cognitive decline. Discrimination tests were used to evaluate the incremental predictive value of the TyG index beyond conventional risk factors.

RESULTS

During the follow-up, compared with those in the bottom quartile group, participants in the top TyG quartile group presented a 51% increase in the risk of cognitive decline (OR 1.51 (95% CI: 1.06-2.14)). As shown by discrimination tests, adding the TyG index into the conventional model resulted in a slight improvement in predicting the risk of cognitive decline (NRI 16.00% (p = 0.004)).

CONCLUSION

This study demonstrated that increasing values of the TyG index were positively associated with the risk of cognitive decline. Monitoring the TyG index may help in the early identification of individuals at high risk of cognitive deterioration.

Review of the effects of polycystic ovary syndrome on Cognition: Looking beyond the androgen hypothesis

Polycystic-ovary syndrome (PCOS) is the most common endocrine disorder affecting women of reproductive age, and many features associated with PCOS - such as elevated androgens, insulin resistance and inflammation - are known to affect cognition. However, effects of PCOS on cognition are not well-understood. Here we review the current literature on PCOS and cognition, note the extent of PCOS symptomatology studied in relation to cognitive outcomes, and identify key research gaps and common methodological concerns. Findings indicate a pattern of worse performance across cognitive domains and brain measures in women with PCOS relative to non-PCOS controls, as well as a lack of evidence for the common assumption that women with PCOS will have higher performance on tasks with a demonstrated male-advantage due to high testosterone levels. We suggest strategies for moving beyond the focus on elevated androgens, in favor of research practices that account for the nuances and heterogeneity of PCOS symptoms.

A multi-omics study of circulating phospholipid markers of blood pressure

High-throughput techniques allow us to measure a wide-range of phospholipids which can provide insight into the mechanisms of hypertension. We aimed to conduct an in-depth multi-omics study of various phospholipids with systolic blood pressure (SBP) and diastolic blood pressure (DBP). The associations of blood pressure and 151 plasma phospholipids measured by electrospray ionization tandem mass spectrometry were performed by linear regression in five European cohorts (n = 2786 in discovery and n = 1185 in replication). We further explored the blood pressure-related phospholipids in Erasmus Rucphen Family (ERF) study by associating them with multiple cardiometabolic traits (linear regression) and predicting incident hypertension (Cox regression). Mendelian Randomization (MR) and phenome-wide association study (Phewas) were also explored to further investigate these association results. We identified six phosphatidylethanolamines (PE 38:3, PE 38:4, PE 38:6, PE 40:4, PE 40:5 and PE 40:6) and two phosphatidylcholines (PC 32:1 and PC 40:5) which together predicted incident hypertension with an area under the ROC curve (AUC) of 0.61. The identified eight phospholipids are strongly associated with triglycerides, obesity related traits (e.g. waist, waist-hip ratio, total fat percentage, body mass index, lipid-lowering medication, and leptin), diabetes related traits (e.g. glucose, insulin resistance and insulin) and prevalent type 2 diabetes. The genetic determinants of these phospholipids also associated with many lipoproteins, heart rate, pulse rate and blood cell counts. No significant association was identified by bi-directional MR approach. We identified eight blood pressure-related circulating phospholipids that have a predictive value for incident hypertension. Our cross-omics analyses show that phospholipid metabolites in the circulation may yield insight into blood pressure regulation and raise a number of testable hypothesis for future research.

Does obesity-associated insulin resistance affect brain structure and function of adolescents differentially by sex?

Metabolic abnormalities affect the adolescent brain. For equivalent abnormalities in metabolism young people exhibit deficits in more cognitive domains than adults. We examine sex differences performance for adolescents with obesity/insulin resistance (IR) and evaluated how sex and IR effected frontal lobe structures and executive functioning. 125 adolescents underwent medical, cognitive, and brain-imaging assessments. Participants were categorized as insulin sensitive (IS) (QUICKI ≥ 0.350) or IR (QUICKI < 0.350). Degree of IR may affect brain and cognition differentially by sex. Females had positive associations between QUICKI and anterior cingulate cortex (ACC) volume, medial orbito-frontal cortex (OFC) thickness, and scores on the Stroop and Digit Symbol Substitution (DSST) tests. Females with IR tended to have thinner insular cortices. No such associations were found in males. In female adolescents, IR may negatively affect brain structure and function. No such effects were found for males. Although needing more development, hormonal effects and inflammation are potential contributors.

Metabolic Syndrome and Cognitive Function

PURPOSE OF REVIEW

Metabolic syndrome (MetS) is a cluster of cardiovascular disease risk factors that are related to several adverse health outcomes, including poor cognitive function. This review seeks to summarize and critically review select recent findings on the association between MetS and cognition.

RECENT FINDINGS

MetS was associated with lower domain-specific and global cognitive function in most cross-sectional studies, but findings from longitudinal studies are not consistent. The associations varied depending on age, sex, cognitive test, genetic susceptibility, and the duration of follow-up in prospective studies. MetS was associated with a higher risk of mild cognitive impairment (MCI) and progression from MCI to dementia, particularly vascular dementia. Among MetS components, high blood pressure, high waist circumference, and hyperglycemia were the strongest predictors of cognitive function. MetS is associated with higher risk of cognitive impairment. Research is needed on how preventing or treating MetS affects cognition.

The role of cognitive reserve in the relationship between metabolic syndrome and cognitive functioning

Metabolic syndrome (MetS) is a cluster of vascular risk factors that can impact cognition. Cognitive reserve (CR), specifically early operators of reserve (e.g., education), have not been explored in the relationship between MetS and cognition. Adults 45-90 years old (n = 149) underwent neuropsychological testing and evaluation for MetS. Exploratory and confirmatory factor analyses defined neuropsychological domains and created a CR score based on early operators of CR. Regression analyses examined the association among MetS, CR, and neuropsychological performance. CFA revealed two neuropsychological factors: Episodic Memory and Executive Functioning. Controlling for age and physical ability, MetS and CR were significant predictors of the Factors. With CR in the model, MetS became a non-significant predictor of Executive Functioning; CR and physical ability were the most significant predictors. CR and MetS significantly predicted Episodic Memory . The results are discussed in the context of neuroprotective factors and cognitive aging.

Is Midlife Metabolic Syndrome Associated With Cognitive Function Change? The Study of Women's Health Across the Nation

CONTEXT

Metabolic syndrome (MetS) affects cognitive function in late life, particularly in women. But longitudinal research is scarce on associations of MetS with cognitive function during midlife.

OBJECTIVE

To determine associations between MetS exposure and cognitive function trajectories in midlife women.

DESIGN AND SETTING

This is a 17-year prospective, longitudinal study of multiracial/ethnic women in 7 US communities, with annual/biennial assessments.

PARTICIPANTS

Participants were 2149 US women traversing menopause.

EXPOSURE

Exposure consisted of MetS assessments (median 4 assessments over 4 years).

MAIN OUTCOME MEASURES

Main outcome measures were assessments of cognitive function in 3 domains: perceptual speed (symbol digit modalities test, SDMT), episodic memory (East Boston Memory Test, EBMT), and working memory (Digit Span Backward Test, DSB).

RESULTS

By their first cognitive assessment (age 50.7 ± 2.9 years), 29.5% met the criteria for MetS. Women completed a median (interquartile range [IQR]) of 6 (IQR 4-7) follow-up cognitive assessments over 11.2 (IQR 9.2-11.5) years. Women with MetS, compared with those without, had a larger 10-year decline in SDMT z-score (estimate -0.087, 95% confidence interval, -0.150 to -0.024; P = 0.007), after adjustment for cognitive testing practice effects, sociodemographics, lifestyle, mood, and menopause factors. As such, MetS accelerated the 10-year loss of perceptual speed by 24%. MetS did not differentially affect the rate of decline in either immediate (P = 0.534) or delayed (P = 0.740) episodic memory or in working memory (P = 0.584).

CONCLUSIONS

In midlife women MetS exposure was associated with accelerated decline in perceptual speed, but not episodic or working memory.

Metabolic Syndrome and Cardiovascular Disease Impacts on the Pathophysiology and Phenotype of HIV-Associated Neurocognitive Disorders

Evidence from epidemiological studies on the general population suggests that midlife cardiovascular disease (CVD) and/or metabolic syndrome (MetS) are associated with an increased risk of cognitive impairment and dementia later in life. In the modern combined antiretroviral therapy (cART) era, as in the general population, CVD and MetS were strongly and independently associated with poorer cognitive performances of sustained immunovirologically controlled persons living with human immunodeficiency viruses (PLHIVs). Those findings suggest that CV/metabolic comorbidities could be implicated in the pathogenesis of HIV-associated neurocognitive disorders (HAND) and might be more important than factors related to HIV infection or its treatment, markers of immunocompetence, or virus replication. The association between CVD/MetS and cognition decline is driven by still not well-understood mechanisms, but risk might well be the consequence of increased brain inflammation and vascular changes, notably cerebral small-vessel disease. In this review, we highlight the correspondences observed between the findings concerning CVD and MetS in the general population and virus-suppressed cART-treated PLHIVs to evaluate the real brain-aging processes. Indeed, incomplete HIV control mainly reflects HIV-induced brain damage described during the first decades of the pandemic. Given the growing support that CVD and MetS are associated with HAND, it is crucial to improve early detection and assure appropriate management of these conditions.

Compensatory Hippocampal Connectivity in Young Adults With Early-Stage Type 2 Diabetes

CONTEXT

Middle-aged to elderly patients with type 2 diabetes mellitus (T2DM) exhibit reduced functional connectivity and brain atrophy underlying cognitive decrements; however, little is known about brain abnormalities in young patients.

OBJECTIVE

To detect brain anatomical and functional changes in young patients with T2DM during the early disease stage.

DESIGN

Case-control study.

SETTING

Tertiary referral hospital.

PARTICIPANTS

Thirty-five young patients with T2DM (<40 years of age) with no detectable microangiopathy and 32 nondiabetic control subjects.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Subjects underwent neuropsychological assessments and structural and resting-state functional MRI. Both voxel-based morphometry and resting-state functional connectivity analyses were performed.

RESULTS

No significant differences in brain volume were observed between the patients with T2DM and the controls after controlling for age, sex, education, and body mass index. Compared with the controls, the patients showed greater connectivity of the left hippocampus with the left inferior frontal gyrus and the left inferior parietal lobule. Moreover, the enhanced functional connectivity of left hippocampus with the left inferior frontal gyrus significantly correlated with disease severity (urinary albumin-to-creatinine ratio) (r = 0.613, P < 0.001) and executive function (completion time of Stroop Color and Word Test) (r = -0.461, P = 0.005) after false discovery rate correction.

CONCLUSIONS

Our findings suggest an adaptive compensation of brain function to counteract the insidious cognitive decrements during the early stage of T2DM. Additionally, the functional alterations occurring before changes in brain structure and peripheral microangiopathy might serve as early biomarkers related to cognitive decrements.

Type 2 diabetes and later cognitive function in older American Indians: The Strong Heart Study

OBJECTIVES

Insulin resistance is a substantial health issue for American Indians, with type 2 diabetes overrepresented in this population as compared with non-Hispanic whites. Insulin resistance and its related conditions in turn increase risk for dementia and cognitive impairment. The aim of the current study was to determine whether type 2 diabetes and insulin resistance at midlife was associated with later-life cognitive testing in a large sample of older American Indians, aged 65 and older.

METHODS

American Indian participants who underwent both fasting blood draw as part of the Strong Heart Study and had subsequent cognitive testing as part of the later adjunct Cerebrovascular Disease and its Consequences in American Indians study were included (n = 790). Regression models examined type 2 diabetes and impaired fasting glucose and subsequent cognitive test performance as part of a longitudinal study design. The relationship between a continuous measure of insulin resistance and later cognitive test performance was assessed using generalized estimating equations.

RESULTS

Controlling for demographic and clinical factors, verbal fluency and processing speed/working memory were significantly negatively associated with having type 2 diabetes and with insulin resistance, but not with impaired fasting glucose.

CONCLUSION

In this sample of American Indians, type 2 diabetes at midlife was associated with subsequent lower performance on measures of executive function. These results may have important implications for future implementation of diagnostic and intervention services in this population.

Metabolic Syndrome and Neurocognitive Deficits in HIV Infection

BACKGROUND

The adverse consequences of HIV and related comorbidities on the central nervous system remain prevalent in the era of combination antiretroviral therapy. Metabolic syndrome (MetS) is a common comorbidity in HIV and has been linked to increased neurocognitive impairment in the general population. We investigated the association between MetS and neurocognition among persons living with HIV (PLHIV).

METHODS

Participants included 109 PLHIV and 92 HIV-uninfected adults (HIV-) from the Multi-dimensional Successful Aging cohort study at the University of California San Diego (age: M = 50.8, SD = 8.0). Participants completed neuromedical, psychiatric, and neurocognitive assessments. Based on a comprehensive neurocognitive battery, we examined global neurocognitive deficits (based on the entire battery) and neurocognitive deficits in 7 domains (verbal fluency, learning, recall, executive function, working memory, speed of information processing, and fine motor skills). MetS was determined via the standard criteria by the National Cholesterol Education Program's Adult Treatment Panel-III. Covariates examined included demographics and psychiatric comorbidities (and HIV disease characteristics among PLHIV).

RESULTS

MetS had an independent significant effect on global neurocognitive deficits among PLHIV (P = 0.03) but not among their HIV- counterparts (P = 0.93). Among PLHIV, MetS was most strongly associated with the neurocognitive domains of learning, fine motor skills, and executive function. Diabetes and elevated triglycerides were the MetS components most strongly linked with increased global neurocognitive deficits in PLHIV.

CONCLUSIONS

The present findings underscore the need for early identification of PLHIV at risk for MetS and the implementation of preventive and treatment approaches to lessen the development of MetS and neurocognitive impairment among PLHIV.

Metabolic syndrome alters relationships between cardiometabolic variables, cognition and white matter hyperintensity load

Cardiometabolic risk factors influence white matter hyperintensity (WMH) development: in metabolic syndrome (MetS), higher WMH load is often reported but the relationships between specific cardiometabolic variables, WMH load and cognitive performance are uncertain. We investigated these in a Brazilian sample (aged 50–85) with (N = 61) and without (N = 103) MetS. Stepwise regression models identified effects of cardiometabolic and demographic variables on WMH load (from FLAIR MRI) and verbal recall performance. WMH volume was greater in MetS, but verbal recall performance was not impaired. Age showed the strongest relationship with WMH load. Across all participants, systolic blood pressure (SBP) and fasting blood glucose were also contributors, and WMH volume was negatively associated with verbal recall performance. In non-MetS, higher HbA1c, SBP, and number of MetS components were linked to poorer recall performance while higher triglyceride levels appeared to be protective. In MetS only, these relationships were absent but education exerted a strongly protective effect on recall performance. Thus, results support MetS as a construct: the clustering of cardiometabolic variables in MetS alters their individual relationships with cognition; instead, MetS is characterised by a greater reliance on cognitive reserve mechanisms. In non-MetS, strategies to control HbA1c and SBP should be prioritised as these have the largest impact on cognition.

Validation of a single factor representing the indicators of metabolic syndrome as a continuous measure of metabolic load and its association with health and cognitive function

The metabolic syndrome (MetS) is a cluster of risk factors for cardiovascular disease associated with reduced physical fitness, higher disease burden, and impaired cognitive functions. Little is known about the operation of these risk factors in older adults when considered comprehensively without relying on the cut-off values of the single MetS components. The three main aims of the current study were to: (i) establish a latent metabolic load factor (MetL), using confirmatory factor analysis (CFA), and representing a continuous measure of MetL, defined by indicators that are commonly used to separate MetS groups from healthy individuals; (ii) examine the associations of this MetL factor with objective health, and cognitive function in men and women; (iii) compare the magnitude of these associations to those observed for the individual indicators used to define the MetL factor as well to the classical categorized MetS vs. non-MetS groups. The current analysis is based on cross-sectional data from 1,609 participants of the Berlin Aging Study II (mean age = 68.5 years, SD (3.7); 50.1% female). We applied structural equation modeling (SEM) to establish a latent MetL factor defined by the five indicators commonly used to diagnose MetS. The latent MetL factor was associated with physician-assessed morbidity and kidney function (estimated glomerular filtration rate, eGFR) in both men and women, but not with hand grip strength and lung function (Forced Expiratory Volume in 1 Second (FEV1)). In addition, we found a negative association between MetL and fluid intelligence among men. A continuous latent variable approach representing the common variance of MetS indicators is well suited to foster our understanding of human aging as a systemic phenomenon in which risk factors are operating on either side of the normal versus pathological divide.

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.

White matter microstructure and cognitive decline in metabolic syndrome: a review of diffusion tensor imaging

Metabolic syndrome is a cluster of cardiovascular risk factors defined by the presence of abdominal obesity, glucose intolerance, hypertension and/or dyslipidemia. It is a major public health epidemic worldwide, and a known risk factor for the development of cognitive dysfunction and dementia. Several studies have demonstrated a positive association between the presence of metabolic syndrome and worse cognitive outcomes, however, evidence of brain structure pathology is limited. Diffusion tensor imaging has offered new opportunities to detect microstructural white matter changes in metabolic syndrome, and a possibility to detect associations between functional and structural abnormalities. This review analyzes the impact of metabolic syndrome on white matter microstructural integrity, brain structure abnormalities and their relationship to cognitive function. Each of the metabolic syndrome components exerts a specific signature of white matter microstructural abnormalities. Metabolic syndrome and its components exert both additive/synergistic, as well as, independent effects on brain microstructure thus accelerating brain aging and cognitive decline.

Brain amyloid load and its associations with cognition and vascular risk factors in FINGER Study

OBJECTIVE

To investigate brain amyloid pathology in a dementia-risk population defined as cardiovascular risk factors, aging, and dementia risk (CAIDE) score of at least 6 but with normal cognition and to examine associations between brain amyloid load and cognitive performance and vascular risk factors.

METHODS

A subgroup of 48 individuals from the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) main study participated in brain ¹¹C-Pittsburgh compound B (PiB)-PET imaging, brain MRI, and neuropsychological assessment at the beginning of the study. Lifestyle/vascular risk factors were determined as body mass index, blood pressure, total and low-density lipoprotein cholesterol, and glucose homeostasis model assessment. White matter lesions were visually rated from MRIs by a semiquantitative Fazekas score.

RESULTS

Twenty participants (42%) had a positive PiB-PET on visual analysis. The PiB-positive group performed worse in executive functioning tests, included more participants with APOE ε4 allele (50%), and showed slightly better glucose homeostasis compared to PiB-negative participants. PiB-positive and -negative participants did not differ significantly in other cognitive domain scores or other vascular risk factors. There was no significant difference in Fazekas score between the PiB groups.

CONCLUSIONS

The high percentage of PiB-positive participants provides evidence of a successful recruitment process of the at-risk population in the main FINGER intervention trial. The results suggest a possible association between early brain amyloid accumulation and decline in executive functions. APOE ε4 was clearly associated with amyloid positivity, but no other risk factor was found to be associated with positive PiB-PET.

The relationship between salivary C-reactive protein and cognitive function in children aged 11-14years: Does psychopathology have a moderating effect?

Elevated C-reactive protein (CRP), a non-specific biomarker of systemic bodily inflammation, has been associated with more pronounced cognitive impairments in adults with psychiatric disorders, particularly in the domains of memory and executive function. Whether this association is present in early life (i.e., the time at which the cognitive impairments that characterise these disorders become evident), and is specific to those with emerging psychiatric disorders, has yet to be investigated. To this end, we examined the association between salivary CRP and cognitive function in children aged 11-14years and explored the moderating effect of psychopathology. The study utilised data from an established longitudinal investigation of children recruited from the community (N=107) that had purposively over-sampled individuals experiencing psychopathology (determined using questionnaires). CRP was measured in saliva samples and participants completed assessments of cognition (memory and executive function) and psychopathology (internalising and externalising symptoms and psychotic-like experiences). Linear regression models indicated that higher salivary CRP was associated with poorer letter fluency (β=-0.24, p=0.006) and scores on the inhibition (β=-0.28, p=0.004) and inhibition/switching (β=-0.36, p<0.001) subtests of the colour-word interference test, but not with performance on any of the memory tasks (working, visual, and verbal memory tasks). Results were largely unchanged after adjustment for psychopathology and no significant interactions between CRP and psychopathology were observed on any cognitive measure. Our findings provide preliminary evidence that elevated salivary CRP is associated with poorer cognitive function in early life, but that this association is not moderated by concurrent psychopathology. These findings have implications for early intervention strategies that attempt to ameliorate cognitive deficits associated with emerging psychiatric disorders. Further research is needed to determine whether salivary CRP levels can be used as a valid marker of peripheral inflammation among healthy adolescents.

Insulin resistance is associated with reductions in specific cognitive domains and increases in CSF tau in cognitively normal adults

Growing evidence supports the hypothesis that type 2 diabetes (T2D) increases the risk of developing dementia. Experimental evidence from mouse models demonstrates that the induction of T2D/insulin resistance (IR) can promote the accumulation of Alzheimer's disease (AD) pathological features. However, the association of T2D with pathological and clinical phenotypes in humans is unclear. Here we investigate the relationship of indices of IR (HOMA-IR) and pancreatic β-cell function (HOMA-B) with cognitive performance across several domains (Verbal/Visual Episodic Memory, Executive Function, Language and a measure of Global cognition) and AD biomarkers (CSF Aβ42, T-tau/P-tau, hippocampal volume and neocortical Aβ-amyloid burden). We reveal that HOMA-IR (p < 0.001) incrementally increases across diagnostic groups, becoming significantly elevated in the AD group compared with cognitively normal (CN) adults. In CN adults, higher HOMA-IR was associated with poorer performance on measures of verbal episodic memory (p = 0.010), executive function (p = 0.046) and global cognition (p = 0.007), as well as with higher CSF T-tau (p = 0.008) and P-tau (p = 0.014) levels. No association was observed with CSF Aβ or imaging modalities. Together our data suggest that IR may contribute to reduced cognitive performance and the accumulation of CSF tau biomarkers in cognitively normal adults.

Glycemia but not the Metabolic Syndrome is Associated with Cognitive Decline: Findings from the European Male Ageing Study

OBJECTIVE

Previous research has indicated that components of the metabolic syndrome (MetS), such as hyperglycemia and hypertension, are negatively associated with cognition. However, evidence that MetS itself is related to cognitive performance has been inconsistent. This longitudinal study investigates whether MetS or its components affect cognitive decline in aging men and whether any interaction with inflammation exists.

METHODS

Over a mean of 4.4 years (SD ± 0.3), men aged 40-79 years from the multicenter European Male Ageing Study were recruited. Cognitive functioning was assessed using the Rey-Osterrieth Complex Figure (ROCF), the Camden Topographical Recognition Memory (CTRM) task, and the Digit Symbol Substitution Test (DSST). High-sensitivity C-reactive protein (hs-CRP) levels were measured using a chemiluminescent immunometric assay.

RESULTS

Overall, 1,913 participants contributed data to the ROCF analyses and 1,965 subjects contributed to the CTRM and DSST analyses. In multiple regression models the presence of baseline MetS was not associated with cognitive decline over time (p > 0.05). However, logistic ordinal regressions indicated that high glucose levels were related to a greater risk of decline on the ROCF Copy (β = -0.42, p < 0.05) and the DSST (β = -0.39, p < 0.001). There was neither a main effect of hs-CRP levels nor an interaction effect of hs-CRP and MetS at baseline on cognitive decline.

CONCLUSION

No evidence was found for a relationship between MetS or inflammation and cognitive decline in this sample of aging men. However, glycemia was negatively associated with visuoconstructional abilities and processing speed.

Insulin Resistance Predicts Cognitive Decline: An 11-Year Follow-up of a Nationally Representative Adult Population Sample

OBJECTIVE

The aim of this study was to examine whether insulin resistance, assessed by HOMA of insulin resistance (HOMA-IR), is an independent predictor of cognitive decline.

RESEARCH DESIGN AND METHODS

The roles of HOMA-IR, fasting insulin and glucose, HbA_1c, and hs-CRP as predictors of cognitive performance and its change were evaluated in the Finnish nationwide, population-based Health 2000 Health Examination Survey and its 11-year follow-up, the Health 2011 study (n = 3,695, mean age at baseline 49.3 years, 55.5% women). Categorical verbal fluency, word-list learning, and word-list delayed recall were used as measures of cognitive function. Multivariate linear regression analysis was performed and adjusted for previously reported risk factors for cognitive decline.

RESULTS

Higher baseline HOMA-IR and fasting insulin levels were independent predictors of poorer verbal fluency performance (P = 0.0002 for both) and of a greater decline in verbal fluency during the follow-up time (P = 0.004 for both). Baseline HOMA-IR and insulin did not predict word-list learning or word-list delayed recall scores. There were no interactions between HOMA-IR and apolipoprotein E ε4 (APOEε4) genotype, hs-CRP, or type 2 diabetes on the cognitive tests. Fasting glucose and hs-CRP levels at baseline were not associated with cognitive functioning.

CONCLUSIONS

Our results show that higher serum fasting insulin and insulin resistance predict poorer verbal fluency and a steeper decline in verbal fluency during 11 years in a representative sample of an adult population. Prevention and treatment of insulin resistance might help reduce cognitive decline later in life.

Age-Related Changes in Gustatory, Homeostatic, Reward, and Memory Processing of Sweet Taste in the Metabolic Syndrome: An fMRI Study

Age affects the human taste system at peripheral and central levels. Metabolic syndrome is a constellation of risk factors (e.g., abdominal obesity and hypertension) that co-occur, increase with age, and heighten risk for cardiovascular disease, diabetes, and cognitive decline. Little is known about how age, metabolic syndrome, and hunger state interact to influence how the brain processes information about taste. We investigated brain activation during the hedonic evaluation of a pleasant, nutritive stimulus (sucrose) within regions critical for taste, homeostatic energy regulation, and reward, as a function of the interactions among age, metabolic syndrome, and hunger condition. We scanned young and elderly adults, half with risk factors associated with metabolic syndrome twice: Once fasted overnight and once after a preload. Functional magnetic resonance imaging data indicated significant effects of age as well as interactive effects with metabolic syndrome and hunger condition. Age-related differences in activation were dependent on the hunger state in regions critical for homoeostatic energy regulation and basic as well as higher order sensory processing and integration. The effects of age and metabolic syndrome on activation in the insula, orbital frontal cortex, caudate, and the hypothalamus may have particularly important implications for taste processing, energy regulation, and dietary choices.

The Metabolic Syndrome Predicts Longitudinal Changes in Clock Drawing Test Performance in Older Nondemented Hypertensive Individuals

OBJECTIVES

The present study evaluated the metabolic syndrome (MetS) as independent predictor of 1-year longitudinal changes in cognitive function.

METHODS

104 stroke- and dementia-free older hypertensive subjects were studied. MetS was defined by NCEP ATP-III criteria. Cognitive function was assessed by the Clock Drawing Test (CDT); 1-year changes in cognitive function were expressed as annual changes in CDT performance. Brain magnetic resonance imaging studies (1.5T) were performed.

RESULTS

Participants with MetS exhibited greater cognitive decline than those without (-1.78 ± 1.47 versus -0.74 ± 1.44 CDT points, t = 3.348, df = 102, p < 0.001). MetS predicted cognitive decline (β = -0.327, t = -3.059, df = 96, p = 0.003) independently of its components, age, baseline cognition, neuroimaging findings, blood pressure levels, and duration of hypertension. With the exception of systolic blood pressure, none of the individual components of MetS explained 1-year changes in CDT performance.

CONCLUSIONS

MetS as an entity predicted accelerated 1-year decline in cognitive function, assessed by CDT, in a sample of older hypertensive subjects.

Association between adiposity and cognitive function in young men: Hormonal mechanisms

OBJECTIVE

To determine the association between adiposity, hormones, and cognition in young men with abdominal obesity.

METHODS

In this cross-sectional observational study, 53 nondiabetic men with abdominal obesity (mean body mass index, 37.3 kg/m(2) ; age, 22-45 years) and normal intelligence underwent detailed measures of body composition, hormonal profiles, and cognition. Age- and education-adjusted performance in five cognitive domains was examined.

RESULTS

Total fat percentage was negatively associated with visuospatial skills (P = 0.002) and visual memory (P = 0.012). Insulin resistance (homeostatic model assessment of insulin resistance) was also negatively associated with these domains (P = 0.05 and trend, P = 0.06, respectively). Total testosterone levels were negatively associated with executive function and verbal learning and memory (P = 0.04 for each), but free testosterone was not. Sex hormone-binding globulin (SHBG) was also inversely associated with performance in these domains (P = 0.015 and trend, P = 0.09, respectively). In a stepwise regression model including percentage fat, homeostatic model assessment of insulin resistance, SHBG, and free testosterone, SHBG was the only variable selected for executive function (P = 0.05) and showed a trend for verbal learning and memory (P = 0.09).

CONCLUSIONS

Adiposity and insulin resistance were associated with worse function in visual domains. An unexpected negative association is reported between SHBG and cognitive measures, which seemed to be independent of free testosterone levels.

Association between the Cardio-Ankle Vascular Index and Executive Function in Community-Dwelling Elderly People

AIM

The aim of this study was to investigate the cross-sectional association between arterial stiffness (AS) measured with the cardio-ankle vascular index (CAVI) and executive function in community-dwelling elderly people.

METHODS

Subjects were 140 community-dwelling elderly people who participated in the study at Kobe, Japan during the period of August-September 2014, of which 126 (mean age±SD: 73.2±6.1, female: 67.5%) met the inclusion criteria and completed the study. Age, sex, body mass index, global cognition, existence of chronic disease, medication, smoking history, and years of education were assessed. The degree of AS was assessed using CAVI. Executive function was assessed using the Category Word Fluency Test (CWFT), Letter Word Fluency Test (LWFT), and Digit Symbol Substitution Test (DSST). We used a correlation analysis and multiple linear regression analysis to investigate whether higher CAVI was independently associated with lower executive function.

RESULTS

In the univariate analysis, higher mean CAVI correlated with lower CWFT (rho=－0.21, p=0.020), LWFT (rho=－0.32, p＜0.001), and DSST (rho=－0.31, p＜0.001). In the multivariate analysis, higher mean CAVI was associated with lower LWFT (β=－0.21, p=0.046) after adjusting for confounding factors, although there was no association with CWFT (β=－0.05, p=0.61) and DSST (β=－0.06, p=0.51).

CONCLUSIONS

We found that high CAVI was associated with lower LWFT. These results suggest that arterial stiffness is associated with lower performance in phonemic fluency.

Obesity, metabolic profile, and inhibition failure: Young women under scrutiny

BACKGROUND

The prevalence of obesity, as well as evidence about this pathology as a risk factor for cognitive decline and dementia in the elderly, is increasing worldwide. Executive functions have been found to be compromised in most studies, although the specific results are dissimilar. Obese young women constitute an interesting study and intervention group, having been found to be unaffected by age and hormonal negative effects on cognition and considering that their health problems affect not only themselves but their families and offspring. The objective of the present study was to compare the executive performance of obese young women with that of a healthy control group.

METHODS

A cross-sectional study was done among premenopausal women from a public hospital in Buenos Aires. The sample comprised 113 participants (32 healthy controls and 81 obese women), who were evaluated for depressive and anxiety symptoms (Beck Depression Inventory-II and State-Trait Anxiety Inventory) and executive functioning (Trail-Making Test B, Stroop Color and Word Test, Wisconsin Card Sorting Test, and verbal fluency test). Statistical analysis was done by using the SPSS version 20.0 software.

RESULTS

Among executive functions, a significant difference was found between groups in inhibition (p<0.01). No correlation was found between psychopathologic measures and Stroop Test Interference results. We found slight correlations between Stroop Test Interference results, waist circumference, fat mass and HDL-cholesterol. In obese group, there was a negative slightly correlation between this cognitive test and 2h post-load glucose level.

CONCLUSIONS

Inhibition was decreased in our obese young women group, and glucose/lipid metabolism may be involved in this association. The cognitive impairment is comparable with that described in addictive conditions. Our conclusions support the concept of multidisciplinary management of obese patients from the time of diagnosis. Detecting and understanding cognitive dysfunction in this population is essential to providing appropriate treatment.

Regional Brain Glucose Hypometabolism in Young Women with Polycystic Ovary Syndrome: Possible Link to Mild Insulin Resistance

Objective

To investigate whether cerebral metabolic rate of glucose (CMR_glu) is altered in normal weight young women with polycystic ovary syndrome (PCOS) who exhibit mild insulin resistance.

Materials and methods

Seven women with PCOS were compared to eleven healthy female controls of similar age, education and body mass index. Regional brain glucose uptake was quantified using FDG with dynamic positron emission tomography and magnetic resonance imaging, and its potential relationship with insulin resistance assessed using the updated homeostasis model assessment (HOMA2-IR). A battery of cognitive tests was administered to evaluate working memory, attention and executive function.

Results

The PCOS group had 10% higher fasting glucose and 40% higher HOMA2-IR (p ≤ 0.035) compared to the Controls. The PCOS group had 9–14% lower CMR_glu in specific regions of the frontal, parietal and temporal cortices (p ≤ 0.018). A significant negative relation was found between the CMR_glu and HOMA2-IR mainly in the frontal, parietal and temporal cortices as well as in the hippocampus and the amygdala (p ≤ 0.05). Globally, cognitive performance was normal in both groups but scores on the PASAT test of working memory tended to be low in the PCOS group.

Conclusions

The PCOS group exhibited a pattern of low regional CMR_glu that correlated inversely with HOMA2-IR in several brain regions and which resembled the pattern seen in aging and early Alzheimer’s disease. These results suggest that a direct association between mild insulin resistance and brain glucose hypometabolism independent of overweight or obesity can exist in young adults in their 20s. Further investigation of the influence of insulin resistance on brain glucose metabolism and cognition in younger and middle-aged adults is warranted.

Insulin resistance is associated with poorer verbal fluency performance in women

AIMS/HYPOTHESIS

Type 2 diabetes is an independent risk factor for cognitive decline. Insulin resistance occurring during midlife may increase the risk of cognitive decline later in life. We hypothesised that insulin resistance is associated with poorer cognitive performance and that sex and APOE*E4 might modulate this association.

METHODS

The association of insulin resistance and APOE*E4 genotype on cognitive function was evaluated in a nationwide Finnish population-based study (n = 5,935, mean age 52.5 years, range 30-97 years). HOMA-IR was used to measure insulin resistance. Cognitive function was tested by word-list learning, word-list delayed-recall, categorical verbal fluency and simple and visual-choice reaction-time tests. Linear regression analysis was used to determine the association between HOMA-IR and the results of the cognitive tests.

RESULTS

Higher HOMA-IR was associated with poorer verbal fluency in women (p < 0.0001) but not in men (p = 0.56). Higher HOMA-IR was also associated with poorer verbal fluency in APOE*E4 -negative individuals (p = 0.0003), but not in APOE*E4 carriers (p = 0.28). Furthermore, higher HOMA-IR was associated with a slower simple reaction time in the whole study group (p = 0.02).

CONCLUSIONS/INTERPRETATION

To our knowledge, this is the first comprehensive, population-based study, including both young and middle-aged adults, to report that female sex impacts the association of HOMA-IR with verbal fluency. Our study was cross-sectional, so causal effects of HOMA-IR on cognition could not be evaluated. However, our results suggest that HOMA-IR could be an early marker for an increased risk of cognitive decline in women.

Brain health and shared risk factors for dementia and stroke

Impaired brain health encompasses a range of clinical outcomes, including stroke, dementia, vascular cognitive impairment, cognitive ageing, and vascular functional impairment. Conditions associated with poor brain health represent leading causes of global morbidity and mortality, with projected increases in public health burden as the population ages. Many vascular risk factors are shared predictors for poor brain health. Moreover, subclinical brain MRI markers of vascular damage are risk factors shared between stroke and dementia, and can be used for risk stratification and early intervention. The broad concept of brain health has resulted in a conceptual shift from vascular risk factors to determinants of brain health. Global campaigns to reduce cardiovascular diseases by targeting modifiable risk factors are necessary and will have a broad impact on brain health. Research is needed on the distinct and overlapping aetiologies of brain health conditions, and to define MRI markers to help clinicians identify patients who will benefit from aggressive prevention measures.

Executive dysfunction assessed by Clock-Drawing Test in older non-demented subjects with metabolic syndrome is not mediated by white matter lesions

AIMS

Metabolic syndrome (MetS) has been associated with greater occurrence of white matter hyperintensities (WMH). It remains uncertain whether MetS as a construct is associated with poorer cognitive performances. This study explores whether MetS is associated with poorer performances in global and domain-specific cognitive tests in older non-demented subjects independently of its individual components, WMH severity and other variables.

METHODS

MetS was diagnosed according to the National Cholesterol Education Program Adult Treatment Panel III definition. Brain magnetic resonance studies (1.5T) were performed. Deep and periventricular WMH were graded using the Fazekas scale. Subjects underwent the Mini-Mental State Examination, the Babcock Short Story Recall test and the Clock-Drawing Test (CDT).

RESULTS

Eighty community-dwellers aged 67-91 years were studied. Subjects with MetS (n = 35) had more severe WMH, and poorer performances on the CDT (P = 0.003) and the Babcock Short Story Recall test (P = 0.027). After multiple adjustment, MetS was inversely associated with CDT scores (B = -1.285; 95% confidence interval = -1.996--0.575; P = 0.001) but not with episodic memory. Results were not affected by WMH severity. Interestingly, none of the individual components of MetS predicted poorer cognitive performances.

CONCLUSIONS

Impairment in executive functions assessed by CDT may represent an early and specific sign of cognitive decline in older individuals with MetS. Future longitudinal studies are needed to better establish the predictive role of MetS on dementia and to demonstrate the possibility of dementia prevention by targeting MetS.

Relationship between Insulin-Resistance Processing Speed and Specific Executive Function Profiles in Neurologically Intact Older Adults

This study investigated the relationship between insulin-resistance and constituent components of executive function in a sample of neurologically intact older adult subjects using the homeostasis model assessment (HOMA-IR) and latent factors of working memory, cognitive control and processing speed derived from confirmatory factor analysis. Low-density lipoprotein (LDL), mean arterial pressure (MAP), along with body mass index (BMI) and white matter hypointensity (WMH) were used to control for vascular risk factors, adiposity and cerebrovascular injury. The study included 119 elderly subjects recruited from the University of California, San Francisco Memory and Aging Center. Subjects underwent neuropsychological assessment, fasting blood draw and brain magnetic resonance imaging (MRI). Partial correlations and linear regression models were used to examine the HOMA-IR-executive function relationship. Pearson correlation adjusting for age showed a significant relationship between HOMA-IR and working memory (rp = -.18; p = .047), a trend with cognitive control (rp = -.17; p = .068), and no relationship with processing speed (rp = .013; p = .892). Linear regression models adjusting for demographic factors (age, education, and gender), LDL, MAP, BMI, and WMH indicated that HOMA-IR was negatively associated with cognitive control (r = -.256; p = .026) and working memory (r = -.234; p = .054). These results suggest a greater level of peripheral insulin-resistance is associated with decreased cognitive control and working memory. After controlling for demographic factors, vascular risk, adiposity and cerebrovascular injury, HOMA-IR remained significantly associated with cognitive control, with working memory showing a trend. These findings substantiate the insulin-resistance-executive function hypothesis and suggest a complex interaction, demonstrated by the differential impact of insulin-resistance on processing speed and specific aspects of executive function.

Is there an association between metabolic syndrome and cognitive function in very old adults? The Newcastle 85+ Study

OBJECTIVES

To determine, using data from the Newcastle 85+ Study, whether there is an association between modern diagnostic criteria for metabolic syndrome (MetS) and cognitive function in very old adults (≥85) and whether inflammation, physical activity, or diabetes mellitus status affects this association.

DESIGN

Longitudinal, population-based cohort study.

SETTING

Newcastle and North Tyneside, United Kingdom.

PARTICIPANTS

Community-dwelling and institutionalized men and women recruited through general practices (N = 845).

MEASUREMENTS

MetS was defined according to the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) criteria. Cross-sectional and prospective (up to 5 years of follow-up) associations between MetS and global cognitive function (assessed using the Mini-Mental State Examination (MMSE)) and between MetS and attention and episodic memory (assessed using the Cognitive Drug Research battery) were performed.

RESULTS

MetS was not associated with cognitive function at baseline or cognitive change over time. Lack of association was not because MetS was predictive of subsequent mortality. Of the individual components of the MetS criteria, high blood pressure was associated with better cognitive function at baseline (MMSE: β (standard error (SE)) = -0.716 (0.152), P < .001), and low high-density lipoprotein cholesterol was associated with poorer global cognitive function at baseline (MMSE: 0.436 (0.131), P = .001).

CONCLUSION

The association between MetS and cognitive decline, which has been described in younger populations (<75), was not apparent in this population of individuals aged 85 and older at baseline.

The association of metabolic syndrome and aging with cognition in Asian men

BACKGROUND

The present cross-sectional study examined the associations of individual metabolic factors and age with the short-term memory and perceptual capacity in 472 healthy Asian men.

METHODS

The symbol digit and digit span tests from the Swedish Performance Evaluation System were used to assess the perceptual capacity and memory cognitive domains. Linear regression with the stepwise method, and multivariate analyses of the General Linear Model with the Bonferroni correction for multiple comparisons were carried out with the SPSS 21.0 package.

RESULTS

High blood pressure and HDL were not significantly associated with either short-term memory or perceptual capacity. Age and glucose level were negatively associated but regular physical exercise was positively associated with perceptual capacity. On the other hand, high triglyceride level (TG) was positively associated but high waist/height ratio was negatively associated with short-term memory. When men without any component of the metabolic syndrome (MetS) were compared with men with one, two or three or more components of MetS, no significant differences in cognitive performance were noted.

CONCLUSION

Not all the metabolic factors were significantly associated with short-term memory or the perceptual capacity domains. Those that were did not show a sufficiently consistent pattern of association to support a role for MetS as a whole in cognitive decline with aging. It may not be meaningful to evaluate the association of MetS as a whole with cognition.

Metabolic syndrome is associated with poor memory and executive performance in elderly community residents: the PROOF study

OBJECTIVE

Aging is associated with a loss of cognitive performance and an increasing occurrence of cardiovascular events. Moreover, cardiovascular risk factors are linked to cognitive impairment and dementia. Whereas individual components of metabolic syndrome (Met S) have been reported to be linked to cognitive decline and dementia, there are very few studies on Met S as a whole. The present study aims to assess the relationship between Met S and its components and cognitive functioning in a cohort of elderly non-demented community residents.

DESIGN

Population-based cohort study (PROOF study). Cross-sectional analysis.

PARTICIPANTS

Dementia-free community-dwellers aged 65.

MEASURES

The PROOF participants underwent an extensive neuropsychological battery at baseline. Summary cognitive measures including memory, attention, and executive performance were created by converting the individual test results to Z scores and computing the average scores within each domain. Each of the three cognitive scores was individually compared between groups as a function of Met S. The cognitive scores and the covariates which were significant in univariate analyses were then included in logistic regression models.

RESULTS

A significant association was observed between the presence of metabolic syndrome, poor memory, and executive function even after adjusting for confounding factors (memory: odds ratio: 1.77, p = 0.008; executive functions: odds ratio: 1.91, p = 0.002).

CONCLUSIONS

Our study showed that in a sample of elderly community dwellers, Met S was associated with poor memory and executive performance. These results underline the importance of detecting and managing metabolic syndrome components to prevent cognitive impairment and dementia.

Midlife metabolic syndrome and neurocognitive function in a mixed Asian sample

BACKGROUND

An association between metabolic syndrome (MetS) and disturbances in neurocognitive function has been identified in Caucasians but the nature and extent of impaired cognition in Asian MetS patients, who may be at greater risk of degenerative cognitive decline, remains unspecified.

METHODS

A cross-sectional study was conducted at the National University Hospital of Singapore. Participants were recruited from a diabetes clinic at the National University Hospital. Fifty-three patients who met MetS criteria and 44 clinical controls were recruited. All participants were 55 years and above and community ambulant. Neurocognitive function was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). CANTAB performances between MetS and control groups were examined with analysis of variance (ANOVA) and the relative contributions of vascular risk, and intrademographic factors on CANTAB scores were dilineated with stepwise regression analyses.

RESULTS

Participants with MetS consistently performed significantly worse than controls across all CANTAB subtests. Education and Chinese race were found to be potential protective factors.

CONCLUSIONS

Executive and memory impairment is present in Asian patients with midlife MetS who may be particularly vulnerable to the detrimental impact of MetS in midlife.

The impact of glucose disorders on cognition and brain volumes in the elderly: the Sydney Memory and Ageing Study

Type 2 diabetes predicts accelerated cognitive decline and brain atrophy. We hypothesized that impaired fasting glucose (IFG) and incident glucose disorders have detrimental effects on global cognition and brain volume. We further hypothesized that metabolic and inflammatory derangements accompanying hyperglycaemia contribute to change in brain structure and function. This was a longitudinal study of a community-dwelling elderly cohort with neuropsychological testing (n = 880) and brain volumes by magnetic resonance imaging (n = 312) measured at baseline and 2 years. Primary outcomes were global cognition and total brain volume. Secondary outcomes were cognitive domains (processing speed, memory, language, visuospatial and executive function) and brain volumes (hippocampal, parahippocampal, precuneus and frontal lobe). Participants were categorised as normal, impaired fasting glucose at both assessments (stable IFG), baseline diabetes or incident glucose disorders (incident diabetes or IFG at 2 years). Measures included inflammatory cytokines and oxidative metabolites. Covariates were age, sex, education, non-English speaking background, smoking, blood pressure, lipid-lowering or antihypertensive medications, mood score, apolipoprotein E genotype and baseline cognition or brain volume. Participants with incident glucose disorders had greater decline in global cognition and visuospatial function compared to normal, similar to that observed in baseline diabetes. Homocysteine was independently associated with the observed effect of diabetes on executive function. Apolipoprotein E genotype did not influence the observed effects of diabetes on cognition. Incident glucose disorders and diabetes were also associated with greater 2-year decline in total brain volume, compared to normal (40.0 ± 4.2 vs. 46.7 ± 5.7 mm(3) vs. 18.1 ± 6.2, respectively, p < 0.005). Stable IFG did not show greater decline in global cognition or brain volumes compared to normal. Incident glucose disorders, like diabetes, are associated with accelerated decline in global cognition and brain volumes in non-demented elderly, whereas stable IFG is not. Preventing deterioration in glucose metabolism in the elderly may help preserve brain structure and function.

Factors associated with cognitive decline in older adults with type 2 diabetes mellitus during a 6-year observation

AIMS

Type 2 diabetes mellitus (T2DM) is a risk for cognitive decline in older adults. The current study was carried out to determine the factors associated with cognitive decline.

METHODS

The older T2DM patients (aged ≥65 years, mean age 79.2 ± 5.1 years) were observed for 6 years, and the mean values in clinical indicators of participants with and without cognitive decline over a 6-year period were compared. Then, multiple logistic analysis was carried out to determine the factors associated with cognitive decline. Separate analyses were also carried out for each of five cognitive assessments (Mini-Mental State Examination, word immediate and delayed recall, Stroop test, digit symbol substitution).

RESULTS

In the composite of several cognitive assessments, higher age and a lower level of high-density lipoprotein cholesterol were associated with cognitive decline in older T2DM patients. Lower systolic blood pressure was associated with a decline in delayed word list recall. Higher plasma insulin level was associated with a decline in the Stroop test performance.

CONCLUSION

Lower high-density lipoprotein cholesterol was significantly associated with general cognitive decline in older T2DM patients during our 6-year observation. Several other factors were also associated with cognitive assessments of various cognitive domains.

The metabolic syndrome and cognitive decline in the Atherosclerosis Risk in Communities study (ARIC)

BACKGROUND

Midlife metabolic syndrome (MetS) may impact cognitive health as a construct independently of hypertension, hyperlipidemia and other components.

METHODS

10,866 participants aged 45-64 years at baseline were assessed for MetS and completed cognitive testing at two later time points (3 and 9 years from the baseline visit).

RESULTS

MetS is associated with increased odds of low cognitive performance in the domains of executive function and word fluency, but not with 6-year cognitive decline. Individual MetS components explained this association (hypertension, diabetes, low HDL, elevated triglycerides and increased waist circumference).

CONCLUSIONS

A focus on the individual risk factors as opposed to MetS during midlife is important to reduce the incidence of cognitive impairment in later life.

Executive functioning and the metabolic syndrome: a project FRONTIER study

Decrements in cognitive functioning have been linked to the metabolic syndrome (MetS), a risk factor for cardiovascular disease defined by the presence of three of the following: elevated blood pressure, increased waist circumference, elevated blood glucose, elevated triglycerides, and low high-density lipoprotein cholesterol. We examined the relationship between four measures of executive functioning (EF) and MetS as diagnosed by National Heart, Lung, and Blood Institute-American Heart Association criteria. MetS was examined in a rural population of 395 persons with a mean age of 61.3 years, 71.4% women, 37.0% Hispanic, 53.7% White non-Hispanic. There was a 61.0% prevalence of MetS. We derived a factor score from the four executive function measures which was used to compare those with and without the syndrome, as well as any additive effects of components of the syndrome. Those with MetS exhibited significantly poorer performance than those without the syndrome. However, there was no additive effect, having more components of the syndrome was not related to lower performance. The presence of MetS was associated with poorer EF in this rural cohort of community dwelling volunteers.

Metabolic and endocrine correlates of cognitive function in healthy young women

OBJECTIVE

Obesity has been associated with cognitive decline in longitudinal studies of older individuals. We hypothesized that the cognitive sequelae of obesity may be detectable in the reproductive years. In addition, we explored the hypothesis that these associations may be mediated by the hormonal milieu.

DESIGN AND METHODS

Of 49 young healthy lean and overweight women aged 20-45, we investigated the association between performance on a battery of cognitive tests, body composition parameters [body mass index, total fat, abdominal (visceral, subcutaneous, and total) adipose tissue, and muscle], and hormone levels (insulin, adiponectin, leptin, insulin-like growth factor 1 (IGF-1), estrogen, testosterone, and vitamin D).

RESULTS

We found a significant negative association between both visceral adiposity and muscle, and performance in the domain of verbal learning and memory, after controlling for age and education. Other body composition parameters showed similar trends (0.05 < P < 0.10). Additionally, the degree of insulin resistance was negatively associated with executive function domain. None of the associations between the other hormones examined (adipokines, IGF-1, gonadal hormones, and vitamin D) and cognitive function were significant.

CONCLUSION

These preliminary findings suggest a possible association between obesity and cognitive function in healthy young women of reproductive age. More research is warranted into the potential modulatory effect of insulin resistance on this association.

Metabolic reserve as a determinant of cognitive aging

Mild cognitive impairment (MCI) and Alzheimer's disease (AD) represent points on a continuum of cognitive performance in aged populations. Cognition may be impaired or preserved in the context of brain aging. One theory to account for memory maintenance in the context of extensive pathology involves 'cognitive reserve', or the ability to compensate for neuropathology through greater recruitment of remaining neurons. In this review, we propose a complementary hypothesis of 'metabolic reserve', where a brain with high metabolic reserve is characterized by the presence of neuronal circuits that respond adaptively to perturbations in cellular and somatic energy metabolism and thereby protects against declining cognition. Lifestyle determinants of metabolic reserve, such as exercise, reduced caloric intake, and intake of specific dietary components can promote neuroprotection, while pathological states arising from sedentary lifestyles and excessive caloric intake contribute to neuronal endangerment. This bidirectional relationship between metabolism and cognition may be mediated by alterations in central insulin and neurotrophic factor signaling and glucose metabolism, with downstream consequences for accumulation of amyloid-β and hyperphosphorylated tau. The metabolic reserve hypothesis is supported by epidemiological findings and the spectrum of individual cognitive trajectories during aging, with additional data from animal models identifying potential mechanisms for this relationship. Identification of biomarkers for metabolic reserve could assist in generating a predictive model for the likelihood of cognitive decline with aging.