Diabetes and cognitive systems in older black and white persons

The MindMoves Trial: Cross-Sectional Analyses of Baseline Vascular Risk and Cognition in Older Women with Cardiovascular Disease

Background

Vascular diseases, including atherosclerotic cardiovascular disease (ASCVD) and stroke, increase the risk of Alzheimer's disease and cognitive impairment. Serum biomarkers, such as brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and insulin-like growth factor 1 (IGF-1), may be indicators of cognitive health.

Objective

We examined whether vascular risk was associated with levels of cognition and serum biomarkers in older women with cardiovascular disease (CVD).

Methods

Baseline data from a lifestyle trial in older women (n = 253) with CVD (NCT04556305) were analyzed. Vascular risk scores were calculated for ASCVD (ASCVD risk estimator) and stroke (CHA2DS2-VASc) based on published criteria. Cognition-related serum biomarkers included BDNF, VEGF, and IGF-1. Cognition was based on a battery of neuropsychological tests that assessed episodic memory, semantic memory, working memory, and executive function. A series of separate linear regression models were used to evaluate associations of vascular risk scores with outcomes of cognition and serum biomarkers. All models were adjusted for age, education level, and racial and ethnic background.

Results

In separate linear regression models, both ASCVD and CHA2DS2-VASc scores were inversely associated with semantic memory (β= -0.22, p = 0.007 and β= -0.15, p = 0.022, respectively), with no significant findings for the other cognitive domains. There were no significant associations between vascular risk scores and serum biomarkers.

Conclusions

Future studies should prospectively examine associations between vascular risk and cognition in other populations and additionally consider other serum biomarkers that may be related to vascular risk and cognition.

Race and sex differences in the association between lifespan glycemic status and midlife cognitive function: the Bogalusa heart study

Introduction

Glycemic markers throughout life are associated with increased risk of midlife cognitive decline, yet it is unclear whether these associations differ by race and sex.

Methods

This study used cross-sectional analysis of prospectively maintained cohort. 1,295 participants in the Bogalusa Heart Study, a biracial epidemiological cohort located in a micropolitan area core setting, provided fasting plasma insulin (FPI) and glucose (FPG) biannually from 1973 to 2016. Memory, executive function (EF), attention, working memory (WM), and global cognition (GC), collected 2013-2016. Glycemic markers (i.e., FPG, FPI, and HOMA-IR) averaged within lifespan epochs (≤ 20 years, childhood/adolescence (C/A); 21-40 years, early adulthood (EA); and 40-58 years, midlife). Linear regression models were analyzed for each epoch and separate models were analyzed with sex and race, education as a covariate.

Results

Sample was 59% women, 34% African American (AA). Among women, higher C/A FPG was associated with poorer memory and poorer GC. Higher EA FPG was associated with poorer WM. Among men, higher EA HOMA-IR was associated with worse attention. Higher C/A HOMA-IR and FPI were associated with better memory, as was higher EA FPI. Among AA, higher C/A FPG was associated with worse attention, EF, and GC. Higher EA HOMA-IR was associated with worse attention. Higher midlife FPI and C/A HOMA-IR were associated with worse WM and EF among White Americans (WAs).

Discussion

Markers indicative of hyperglycemia at different epochs were associated with worse midlife cognition in women, AAs, and WAs; but not in men. Differences in the relationship between lifespan glycemic exposures and midlife cognition could reflect broader health disparities.

Genome-Wide Mapping Implicates 5-Hydroxymethylcytosines in Diabetes Mellitus and Alzheimer's Disease

BACKGROUND

Diabetes mellitus (DM) is a recognized risk factor for dementia. Because DM is a potentially modifiable condition, greater understanding of the mechanisms linking DM to the clinical expression of Alzheimer's disease dementia may provide insights into much needed dementia therapeutics.

OBJECTIVE

In this feasibility study, we investigated DM as a dementia risk factor by examining genome-wide distributions of the epigenetic DNA modification 5-hydroxymethylcytosine (5hmC).

METHODS

We obtained biologic samples from the Rush Memory and Aging Project and used the highly sensitive 5hmC-Seal technique to perform genome-wide profiling of 5hmC in circulating cell-free DNA (cfDNA) from antemortem serum samples and in genomic DNA from postmortem prefrontal cortex brain tissue from 80 individuals across four groups: Alzheimer's disease neuropathologically defined (AD), DM clinically defined, AD with DM, and individuals with neither disease (controls).

RESULTS

Distinct 5hmC signatures and biological pathways were enriched in persons with both AD and DM versus AD alone, DM alone, or controls, including genes inhibited by EGFR signaling in oligodendroglia and those activated by constitutive RHOA. We also demonstrate the potential diagnostic value of 5hmC profiling in circulating cfDNA. Specifically, an 11-gene weighted model distinguished AD from non-AD/non-DM controls (AUC = 91.8%; 95% CI, 82.9-100.0%), while a 4-gene model distinguished DM-associated AD from AD alone (AUC = 87.9%; 95% CI, 77.5-98.3%).

CONCLUSION

We demonstrate in this small sample, the feasibility of detecting and characterizing 5hmC in DM-associated AD and of using 5hmC information contained in circulating cfDNA to detect AD in high-risk individuals, such as those with diabetes.

Cognitive Outcome 1 Year After Mild Traumatic Brain Injury: Results From the TRACK-TBI Study

BACKGROUND AND OBJECTIVES

The objectives of this study were to develop and establish concurrent validity of a clinically relevant definition of poor cognitive outcome 1 year after mild traumatic brain injury (mTBI), to compare baseline characteristics across cognitive outcome groups, and to determine whether poor 1-year cognitive outcome can be predicted by routinely available baseline clinical variables.

METHODS

Prospective cohort study included 656 participants ≥17 years of age presenting to level 1 trauma centers within 24 hours of mTBI (Glasgow Coma Scale score 13-15) and 156 demographically similar healthy controls enrolled in the Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study. Poor 1-year cognitive outcome was defined as cognitive impairment (below the ninth percentile of normative data on ≥2 cognitive tests), cognitive decline (change score [1-year score minus best 2-week or 6-month score] exceeding the 90% reliable change index on ≥2 cognitive tests), or both. Associations of poor 1-year cognitive outcome with 1-year neurobehavioral outcomes were performed to establish concurrent validity. Baseline characteristics were compared across cognitive outcome groups, and backward elimination logistic regression was used to build a prediction model.

RESULTS

Mean age of participants with mTBI was 40.2 years; 36.6% were female; 76.6% were White. Poor 1-year cognitive outcome was associated with worse 1-year functional outcome, more neurobehavioral symptoms, greater psychological distress, and lower satisfaction with life (all p < 0.05), establishing concurrent validity. At 1 year, 13.5% of participants with mTBI had a poor cognitive outcome vs 4.5% of controls (p = 0.003). In univariable analyses, poor 1-year cognitive outcome was associated with non-White race, lower education, lower income, lack of health insurance, hyperglycemia, preinjury depression, and greater injury severity (all p < 0.05). The final multivariable prediction model included education, health insurance, preinjury depression, hyperglycemia, and Rotterdam CT score ≥3 and achieved an area under the curve of 0.69 (95% CI 0.62-0.75) for the prediction of a poor 1-year cognitive outcome, with each variable associated with >2-fold increased odds of poor 1-year cognitive outcome.

DISCUSSION

Poor 1-year cognitive outcome is common, affecting 13.5% of patients with mTBI vs 4.5% of controls. These results highlight the need for better understanding of mechanisms underlying poor cognitive outcome after mTBI to inform interventions to optimize cognitive recovery.

Plasma Cholesterol Levels as Potential Nutritional Biomarkers for Lewy Body Dementia

BACKGROUND

The relationship between cholesterol level and the risk of developing Alzheimer's disease has been well established, but the relationship between cholesterol level and Lewy body dementia (LBD) is still not well known.

OBJECTIVE

The aim of this case-control study was to explore the association between blood cholesterol levels and LBD in Chinese older adults.

METHODS

A total of 65 patients with LBD and 110 older adult controls were enrolled during the study period. The levels of triglyceride, total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and fasting glucose were measured separately. The associations between LBD, blood cholesterol levels, and fasting glucose levels were assessed using multiple binary logistic regression analyses adjusted for multiple covariates.

RESULTS

Increased plasma LDL-C levels and lower HDL-C levels were independently associated with the risk of LBD in models adjusted for age, sex, education, alcohol use status, smoking status, and vascular disorders. Higher fasting glucose levels may be associated with the risk of LBD.

CONCLUSION

The results of this study suggest that elevated levels of LDL-C and reduced levels of HDL-C were associated with LBD development and therefore are potential nutritional risk factors for LBD. Adjusting diet and individualized and effective cholesterol-lowering therapy in high-risk adults may aid in the prevention or management of LBD.

Influence of endogenous estrogen on a network model of female brain integrity

Recent reports document sex differences in midlife brain integrity and metabolic health, such that more relationships are detectable between metabolic syndrome (MetS) components and markers of brain health in females than in males. Midlife is characterized by a rapid decrease in endogenous estrogen levels for women which is thought to increase risk for cardiometabolic disease and neurocognitive decline. Our study used network models, designed to explore the interconnectedness and organization of relationships among many variables at once, to compare the influence of endogenous estrogen and chronological age on a network of brain and metabolic health in order to investigate the utility of estrogen as a biomarker for brain vulnerability. Data were analyzed from 82 females (ages 40-62). Networks consisted of known biomarkers of risk for late-life cognitive decline: the five components of MetS; Brain-predicted age difference calculated on gray and white matter volume; white matter hyperintensities; Default Mode Network functional connectivity; cerebral concentrations of N-acetyl aspartate, glutamate and myo-inositol; and serum concentrations of estradiol. A second network replaced estradiol with chronological age. Expected influence (EI) of estradiol on the network was -1.190, relative to chronological age at -0.524, indicating that estradiol had a stronger expected influence over the network than age. A negative expected influence indicates that higher levels of estradiol would be expected to decrease the number of relationships in the model, which is thought to indicate lower risk. Overall, levels of estradiol appear more influential than chronological age at midlife for relationships between brain integrity and metabolic health.

Metabolic Syndrome and Cognitive Function in Midlife

OBJECTIVE

Metabolic syndrome (MetS) is a cluster of cardiovascular risk factors associated with cognitive decline. We investigated the relationship between MetS and cognition in middle-aged adults. We hypothesized that higher numbers of MetS components will relate to poorer performance on executive function (EF) tasks as frontal lobe regions critical to EF are particularly vulnerable to cardiovascular disease.

METHODS

197 adults (ages 40-60) participated. MetS was evaluated using established criteria. Composite scores for cognitive domains were computed as follows: Global cognitive function (subtests from the Wechsler Abbreviated Scale of Intelligence, 2nd Edition), EF (Stroop Color Word, Digit Span Backward, and Trails A and B), and memory (California Verbal Learning Test, 2 Edition).

RESULTS

Higher number of MetS components was related to weaker EF-F(4, 191) = 3.94, p = .004, MetS components ß = -.14, p = .044. A similar relationship was detected for tests of memory-F(4, 192) = 7.86, p < .001, MetS components ß = -.15, p = .032. Diagnosis of MetS was not significantly associated with EF domain score (ß = -.05, p = .506) but was significantly associated with memory scores-F(4, 189) = 8.81, p < .001, MetS diagnosis ß = -.19, p = .006.

CONCLUSIONS

Our findings support prior research linking MetS components at midlife to executive dysfunction and demonstrate that MetS, and its components are also associated with poorer memory function. This suggests that cognitive vulnerability can be detected at midlife. Interventions for MetS at midlife could alter cognitive outcomes.

Network Modeling Sex Differences in Brain Integrity and Metabolic Health

Hypothesis-driven studies have demonstrated that sex moderates many of the relationships between brain health and cardiometabolic disease, which impacts risk for later-life cognitive decline. In the present study, we sought to further our understanding of the associations between multiple markers of brain integrity and cardiovascular risk in a midlife sample of 266 individuals by using network analysis, a technique specifically designed to examine complex associations among multiple systems at once. Separate network models were constructed for male and female participants to investigate sex differences in the biomarkers of interest, selected based on evidence linking them with risk for late-life cognitive decline: all components of metabolic syndrome (obesity, hypertension, dyslipidemia, and hyperglycemia); neuroimaging-derived brain-predicted age minus chronological age; ratio of white matter hyperintensities to whole brain volume; seed-based resting state functional connectivity in the Default Mode Network, and ratios of N-acetyl aspartate, glutamate and myo-inositol to creatine, measured through proton magnetic resonance spectroscopy. Males had a sparse network (87.2% edges = 0) relative to females (69.2% edges = 0), indicating fewer relationships between measures of cardiometabolic risk and brain integrity. The edges in the female network provide meaningful information about potential mechanisms between brain integrity and cardiometabolic health. Additionally, Apolipoprotein ϵ4 (ApoE ϵ4) status and waist circumference emerged as central nodes in the female model. Our study demonstrates that network analysis is a promising technique for examining relationships between risk factors for cognitive decline in a midlife population and that investigating sex differences may help optimize risk prediction and tailor individualized treatments in the future.

Racial/Ethnic Disparities in Young Adulthood and Midlife Cardiovascular Risk Factors and Late-life Cognitive Domains: The Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) Study

BACKGROUND

Midlife cardiovascular risk factors (CVRF) increase dementia risk. Less is known about whether CVRF identified before midlife impact late-life cognition in diverse populations.

METHODS

Linear regression models examined hypertension, hyperlipidemia, and overweight/obesity at ages 30 to 59 with late-life executive function, semantic memory, verbal episodic memory, and global cognition in a cohort of Asians, blacks, Latinos, and whites (n=1127; mean age=75.8, range=65 to 98). Models adjusted for age at CVRF, age at cognitive assessment, sex, race/ethnicity, participant education, and parental education.

RESULTS

Overall, 34% had 1 CVRF at ages 30 to 59; 19% had 2+. Blacks (26%) and Latinos (23%) were more likely to have 2+ CVRF than Asians (14%) or whites (13%). Having 2+ CVRF was associated with lower global cognition [β=-0.33; 95% confidence interval (CI)=-0.45, -0.21], executive function (β=-0.26; 95% CI=-0.39, -0.13), verbal episodic memory (β=-0.34; 95% CI=-0.48, -0.20), and semantic memory (β=-0.20; 95% CI=-0.33, -0.07). Interaction by age (P=0.06) indicated overweight/obesity was negatively associated with executive function at ages 30 to 39 but not at ages 40 to 59. Race/ethnic-specific effects showed disparities in CVRF prevalence impact population disparities in late-life cognition.

CONCLUSION

Being overweight/obese in early adulthood and having 2+ CVRF in early adulthood/midlife are modifiable targets to redress racial/ethnic disparities in cognitive impairment and dementia.

The bile acid TUDCA improves glucose metabolism in streptozotocin-induced Alzheimer's disease mice model

Alzheimer's disease (AD) is a neurodegenerative disorder and the major cause of dementia. According to predictions of the World Health Organization, more than 150 million people worldwide will suffer from dementia by 2050. An increasing number of studies have associated AD with type 2 diabetes mellitus (T2DM), since most of the features found in T2DM are also observed in AD, such as insulin resistance and glucose intolerance. In this sense, some bile acids have emerged as new therapeutic targets to treat AD and metabolic disorders. The taurine conjugated bile acid, tauroursodeoxycholic (TUDCA), reduces amyloid oligomer accumulation and improves cognition in APP/PS1 mice model of AD, and also improves glucose-insulin homeostasis in obese and type 2 diabetic mice. Herein, we investigated the effect of TUDCA upon glucose metabolism in streptozotocin-induced AD mice model (Stz). The Stz mice that received 300 mg/kg TUDCA during 10 days (Stz + TUDCA), showed improvement in glucose tolerance and insulin sensitivity, reduced fasted and fed glycemia, increased islet mass and β-cell area, as well as increased glucose-stimulated insulin secretion, compared with Stz mice that received only PBS. Stz + TUDCA mice also displayed lower neuroinflammation, reduced protein content of amyloid oligomer in the hippocampus, improved memory test and increased protein content of insulin receptor β-subunit in the hippocampus. In conclusion, TUDCA treatment enhanced glucose homeostasis in the streptozotocin-induced Alzheimer's disease mice model, pointing this bile acid as a good strategy to counteract glucose homeostasis disturbance in AD pathology.

Association of Low Systolic Blood Pressure with Postmortem Amyloid-β and Tau

BACKGROUND

Vascular mechanisms may contribute to the accumulation of AD pathology.

OBJECTIVE

We examined whether the burden of vascular risk factors proximate to death is associated with amyloid-β and tau levels or modified their known association.

METHODS

We examined the brains of 1, 585 participants from two longitudinal community-based studies of older adults. Amyloid-β and tau were quantified by postmortem examination. The burden of vascular risk factors was summarized by calculating the Framingham general cardiovascular risk score (FRS) proximate to death. Using linear regressions, we examined the association of the FRS with the amyloid-β and tau levels and examined if the FRS modified the association of the amyloid-β with tau.

RESULTS

On average, participants were nearly 90 years old and two-thirds were women. The FRS was not associated with amyloid-β (Spearman r  = -0.00, p  = 0.918) or tau (r = 0.01, p = 0.701). However, the FRS as a whole (estimate = -0.022, SE = 0.008, p = 0.009), and specifically the systolic blood pressure (SBP) component (estimate = -0.033, SE = 0.012, p = 0.009), modified the association of the amyloid-β with tau. Further analysis showed that the association between amyloid-β and tau was stronger at lower levels of SBP.

CONCLUSION

Late-life vascular risk scores were not related to postmortem levels of amyloid-β or tau. However, lower levels of vascular risk scores and SBP were associated with a stronger association between amyloid-β and tau. These data suggest that vascular risk factors may modify the relation of AD pathology markers to one another.

Metabolic syndrome components moderate the association between executive function and functional connectivity in the default mode network

Middle aged individuals with Metabolic Syndrome are at high risk for cognitive decline. Dyssynchrony in the resting state Default Mode Network is one early indicator of brain vulnerability. We set out to explore the relationship between default mode resting state functional connectivity and cognitive performance in both memory and executive domains at midlife in the presence of Metabolic Syndrome components. Seed-based Correlation Analyses were performed between the seed voxel in the posterior cingulate cortex and the medial prefrontal cortex on 200 participants (ages 40-61). Executive domain scores were significantly predicted by the interaction between number of Metabolic Syndrome components and resting state connectivity in the Default Mode Network (p = .004) such that connectivity was negatively related to executive function at higher numbers of Metabolic Syndrome components. Results were not significant for memory. Our findings indicate that clusters of cardiovascular disease risk factors alter functional relationships in the brain and highlights the need to continue exploring how compensatory techniques might operate to support cognitive performance at midlife.

The Relation of Diabetes to Memory Function

PURPOSE OF REVIEW

Research has consistently shown that type 2 diabetes (T2D) is associated with increased risk of all-cause dementia. Because one of the most common clinical presentations of early stage dementia is memory impairment, we examined the relationship of T2D with memory function, using the recently published scientific literature.

RECENT FINDINGS

We conducted a structured review to identify studies of "T2D and memory" published since 2015. After review of the 129 articles retrieved, we identified 14 studies meeting the inclusion and exclusion criteria. Among the eight studies with a single assessment of memory function in time (mostly cross-sectional), six found an association of T2D with lower memory function, but mostly in select subgroups of persons. Separately, six studies included repeated measures of memory (longitudinal design). Four out of six longitudinal studies found that T2D was related with a faster decline in memory, while two did not. Among the four studies showing a relation with memory decline, two had sample sizes of 9000-10,000 persons. Further, three longitudinal studies controlled for hypertension and stroke as covariates, and results suggested that common vascular risk factors and diseases do not account for the relation. While mechanistic studies clearly support a role for cerebrovascular disease in the relation of T2D with cognition, emerging data suggest that insulin resistance in the brain itself may also play a role. Most, but not all, recently published studies suggest that T2D is associated with a lower level and faster decline in memory function. This association does not appear to be fully accounted for by common vascular processes. More research will clarify the mechanisms linking T2D to memory and dementia.

The Contribution of Kidney Disease to Cognitive Impairment in Patients with Type 2 Diabetes

PURPOSE OF REVIEW

This review focuses on the relationships between diabetes, cognitive impairment, and the contribution of kidney disease.

RECENT FINDINGS

We review the independent contributions of parameters of kidney disease, including albuminuria, glomerular filtration, bone/mineral metabolism, and vitamin D synthesis, on cognitive performance in patients with diabetes. Potential pathophysiologic mechanisms underlying these associations are discussed highlighting gaps in existing knowledge. Finally, effects of the dialysis procedure on the brain and cognitive performance are considered. Emphasis is placed on novel non-invasive screening tools with the potential to preserve cerebral perfusion during hemodialysis and limit cognitive decline in patients with diabetic ESKD. Patients with type 2 diabetes and advanced chronic kidney disease suffer a higher prevalence of cognitive impairment. This is particularly true in patients with diabetes and end-stage kidney disease (ESKD).

Atrophy patterns of hippocampal subfields in T2DM patients with cognitive impairment

PURPOSE

To identify the volume changes of hippocampus subfields in T2DM patients with cognitive impairment and to determine how these atrophy patterns associate with impairments in different cognitive domain.

METHODS

A total of 117 individuals were recruited, including T2DM patients with cognitive impairment (T2DM-CI) (n = 34), T2DM patients without cognitive impairment (T2DM-non-CI) (n = 36) and normal controls (NC) (n = 47). All subjects went through a 3.0 T magnetic resonance (MR) scan and a neuropsychological assessment. Hippocampal subfield volumes were processed using the FreeSurfer 6.0.0 and compared among the three groups. Partial correlation analyses were used to estimate the relationship between cognitive function and hippocampal subfield volume, with age, sex, education, and eTIV (estimated total intracranial volume) as covariants.

RESULTS

The total hippocampal volume had a reduction trend among the three groups, and the significantly statistical difference only was found between T2DM-CI group and NC group. Regarding the hippocampal subfields, the volumes of left subiculum, left presubiculum, left fimbria, right CA1 and right molecular layer HP decreased significantly in the T2DM-CI group (P < 0.05/12). Partial correlation analyses showed that the volumes of the left subiculum, left fimbria, and left presubiculum were significantly related to executive function. The right hippocampal CA1 volume was significantly correlated with memory in the T2DM-CI group (P < 0.05). But in T2DM-non-CI group, the correlation between the left fimbria volume and the memory, the left subiculum volume and MoCA were different with the T2DM-CI group and NC group (P < 0.05).

CONCLUSIONS

The smaller the volume of left presubiculum, the worse the executive function, and the atrophy of the right CA1 was related to memory impairment in T2DM-CI group. However the result was the opposite in T2DM-non-CI group. There might be a compensation mechanism of hippocampus of T2DM patients before cognitive impairment.

Exercise Training Induced Changes In Nuclear Magnetic Resonance-Measured Lipid Particles In Mild Cognitively Impaired Elderly African American Volunteers: A Pilot Study

Purpose

Poor cardiorespiratory fitness (CRF) is linked to cognitive deterioration, but its effects on lipid heterogeneity and functional properties in older African American (AA) subjects with mild cognitive impairment (MCI) need elucidation. This study determined whether exercise training-induced changes in blood lipid particle sizes (LPS) were associated with CRF determined by VO₂Max in elderly AAs with MCI. Given the pivotal role of brain-derived neurotrophic factor (BDNF) on glucose metabolism, and therefore, “diabetic dyslipidemia”, we also determined whether changes in LPS were associated with the levels of serum BDNF.

Methods

This analysis included 17 of the 29 randomized elderly AAs with MCI who had NMR data at baseline and after a 6-month training. We used Generalized Linear Regression (GLM) models to examine cardiorespiratory fitness (VO₂Max) effects on training-induced change in LPS in the stretch and aerobic groups. Additionally, we determined whether the level of BDNF influenced change in LPS.

Results

Collectively, mean VO₂Max (23.81±6.17) did not differ significantly between aerobic and stretch groups (difference=3.17±3.56, P=0.495). Training-related changes in very low-density lipoprotein, chylomicrons, and total low-density lipoprotein (LDL) particle sizes correlated significantly with VO₂Max, but not after adjustment for age and gender. However, increased VO₂Max significantly associated with reduced total LDL particle size after similar adjustments (P = 0.046). While stretch exercise associated with increased protective large high-density lipoprotein particle size, the overall effect was not sustained following adjustments for gender and age. However, changes in serum BDNF were associated with changes in triglyceride and cholesterol transport particle sizes (P < 0.051).

Conclusion

Promotion of stretch and aerobic exercise to increase CRF in elderly AA volunteers with MCI may also promote beneficial changes in lipoprotein particle profile. Because high BDNF concentration may reduce CVD risk, training-related improvements in BDNF levels are likely advantageous. Large randomized studies are needed to confirm our observations and to further elucidate the role for exercise therapy in reducing CVD risk in elderly AAs with MCI.

Type 2 diabetes and cognitive dysfunction in minorities: a review of the literature

OBJECTIVES

The purpose of this review was to summarize the current status of knowledge regarding cognitive dysfunction and diabetes in minorities. Literature on the interaction of cognitive dysfunction and diabetes was analyzed to (a) examine the number and characteristics of studies in minority populations; (b) identify tests used to assess cognitive function in diabetes; (c) consider the impact of diabetes on cognitive function; and (d) assess the moderators of the association between diabetes and cognitive function.

DESIGN

A literature review and thematic analysis was conducted. Studies were mapped to describe their design, target population, instruments used, and the physiologic, psychosocial, and socioeconomic findings related to cognitive function and diabetes. Twelve studies met the inclusion criteria.

RESULTS

Hispanics were studied more than any other ethnic group. Rates and degree of cognitive dysfunction were more prevalent in minorities than non-Hispanic whites. Overall, 28 different tests were administered to evaluate cognitive function. There was some variation among findings regarding the relationship of cognitive function and diabetes. Risk for cognitive decline was associated with the diagnosis of diabetes alone, regardless of whether the diabetes was treated or untreated. Higher rates of discrimination were associated with greater cognitive decline Conclusion: Given the context of minority health, there is a potential for higher negative health impact due to the increased prevalence of diabetes and cognitive dysfunction and other related health disparities. Reduction of physiological risk factors for diabetes, consistency in assessment, as well as elimination of structural barriers such as access to care should be helpful in decreasing the incidence of both diabetes and cognitive decline. More research is needed to determine whether the observed differences are modifiable and to identify factors involved in the interaction of diabetes and cognitive decline-not only physiological factors, but factors related to socioeconomic status and quality of life.

Body Mass Index and Decline in Cognitive Function in Older Black and White Persons

Background

While body mass index (BMI) is higher in black compared to white persons, little is known about BMI and change in cognition in cohorts with a large proportion of blacks. We examine relations of BMI with decline in global cognition and five cognitive domains, in older blacks and whites, and determine whether relations differ by race.

Methods

Participants were 2,134 persons without baseline dementia (33% black; 75% women; mean age =77.9 [range 53-100] and education = 14.7 years, Mini-Mental State Examination = 28.0), enrolled in one of two longitudinal, community-based cohort studies of aging (Minority Aging Research Study; Rush Memory and Aging Project). Summary scores of global cognition and five domains were based on 19 neuropsychological tests administered annually. Mixed-effects models, controlling for age, sex, education, and race, were used to examine the relation of baseline BMI to change in cognition.

Results

Baseline BMI = 28.4 units (30.3 in blacks [95% confidence interval (CI): 27.2-27.7]; 27.4 in whites [95% CI: 29.8-30.7]). During a mean annual follow-up of 6 years (SD = 4), lower baseline BMI was related to faster decline in global cognition (p = .002), and semantic memory (p < .001) and episodic memory (p = .004), but not working memory, perceptual speed, or visuospatial ability (all p > .08). The relationship of BMI with change in cognition was not modified by race (all p > .09).

Conclusions

Late-life lower BMI relates to faster rates of decline in cognition, specifically semantic memory and episodic memory, in both blacks and whites. The effect of BMI on cognition appears to be similar in both racial groups.

Hyperglycemia induced the Alzheimer's proteins and promoted loss of synaptic proteins in advanced-age female Goto-Kakizaki (GK) rats

Although both type 2 diabetes mellitus (T2DM) and aging are related with Alzheimer's disease (AD), the effects of aging on the Alzheimer's proteins and the synaptic markers in T2DM have not been investigated. This study, we hypothesized that T2DM rats with advanced-age, aggravates the reduction of synaptic proteins and an increase in the Alzheimer's protein markers. Goto-Kakizaki rats (GK) were used as a T2DM group and wild-type rats (WT) were used as a control group. Rats in each group were categorized by age into young-adult (7 months) and advanced-age rats (12.5 months). Blood was collected in all rats to determine plasma glucose and insulin levels. The brains were used for determining the level of Alzheimer's and synaptic proteins. Our data demonstrated that GK rats had a decreased body weight and increased blood glucose levels, compared to their age-matched WT. p-Tau was increased in both advanced-age WT and GK, compared to their young-adult rats. Moreover, amyloid-beta (Aβ) level was higher in advanced-age GK than their age-matched WT. The synaptic proteins were decreased in advanced-age GK, compared to young-adult GK rats. However, no difference in the level of Alzheimer's proteins and synaptic proteins in the brains of young-adult GK compared to age-matched WT was found. Our data suggested that aging contributes to the pathogenesis of AD and the reduction of synaptic proteins to greater extent in a diabetic than in a healthy condition.

Perceived cognitive deficits are associated with diabetes self-management in a multiethnic sample

Background

People with diabetes have almost twice the risk of developing cognitive impairment or dementia as do those without diabetes, and about half of older adults with diabetes will become functionally disabled or cognitively impaired. But diabetes requires complex self-management: patients must learn about the implications of their disease; manage their diets, physical activity, and medication; and monitor their blood glucose. Difficulties with cognition can hinder these activities.

Methods

The purpose of this study was to explore perceptions of cognitive ability in a multiethnic sample of persons with type 2 diabetes (T2DM). One hundred twenty participants completed surveys assessing perceived memory, executive function, diabetes self-management, and quality of life. Scores on the surveys were examined along with hemoglobin A1C levels and demographics.

Results

Scores for executive function were positively associated with self-reports of dietary adherence and blood glucose monitoring. Perceived memory ability was a significant predictor of quality of life, and executive function was a significant predictor of A1C.

Conclusions

Patients’ perceptions of their cognitive difficulties may assist health care providers in detection of patients’ deficiencies in performing diabetes self-management tasks. The relationships between cognitive difficulties and self-management found in this descriptive study suggest that research on the processes leading to cognitive changes in T2DM is needed, as are studies on how those processes affect diabetes self-management.

Diabetes, Hemoglobin A1C, and Regional Alzheimer Disease and Infarct Pathology

We examined the relationship of diabetes and hemoglobin A1C (A1C) to 2 common causes of dementia. The study included 1228 subjects who underwent annual clinical evaluations and a brain autopsy at death, as part of a Rush longitudinal cohort study of aging. A total of 433 subjects had A1C data available. Neuropathologic evaluations documented the size and location of infarcts. Modified silver stain-based Alzheimer disease (AD) measures included global and regional scores. We used regression analyses to examine associations of diabetes and A1C with overall and regional neuropathology. Diabetes [odds ratio (OR)=0.94; 95% confidence interval (CI), 0.73-1.20) and A1C (OR=0.83; 95% CI, 0.62-1.10) were not associated with global AD pathology across the brain, nor with overall or individual measures of neuropathology in mesial temporal or neocortical regions separately (all P>0.05). Diabetes was associated with a higher odds of any infarct (OR=1.43; 95% CI, 1.07-1.90), and particularly with gross (OR=1.53; 95% CI, 1.14-2.06) but not microinfarcts (P=0.06), and subcortical (OR=1.79; 95% CI, 1.34-2.39) but not cortical infarcts (P=0.83). In summary, we found no relationship of diabetes or A1C with global or regional AD pathology, including in the mesial temporal lobe. Diabetes is associated with gross subcortical infarcts. Our results suggest that the diabetes-dementia link is based on subcortical vascular pathology and not on regional AD pathology.

Cognitive decline following incident and preexisting diabetes mellitus in a population sample

OBJECTIVE

To examine if incident and preexisting diabetes mellitus (DM) were associated with cognitive decline among African Americans (AAs) and European Americans (EAs).

METHODS

Based on a prospective study of 7,740 older adults (mean age 72.3 years, 64% AA, 63% female), DM was ascertained by hypoglycemic medication use and Medicare claims during physician or hospital visits, and cognition by performance on a brief battery for executive functioning, episodic memory, and Mini-Mental State Examination (MMSE). Decline in composite and individual tests among those with incident DM, with preexisting DM, and without DM was studied using a linear mixed effects model with and without change point.

RESULTS

At baseline, 737 (15%) AAs and 269 (10%) EAs had preexisting DM. Another 721 (17%) AAs and 289 (12%) EAs had incident DM in old age. Following incident DM, cognitive decline increased by 36% among AAs and by 40% among EAs compared to those without DM. No significant difference was observed between AAs and EAs (p = 0.64). However, cognitive decline increased by 17% among AAs with preexisting DM compared to those without DM, but no increased decline was observed among EAs with preexisting DM. In secondary analyses, faster decline in executive functioning and episodic memory was observed following incident DM.

CONCLUSIONS

In old age, faster cognitive decline was present among AAs and EAs following incident DM, compared to cognitive decline prior to DM, and among those without DM. This underscores the need for stronger prevention and control of DM in old age.

Factors related to racial differences in late-life level of cognitive function

OBJECTIVE

The study aim was to identify factors associated with racial differences in level of cognitive function in old age.

METHOD

Older Black (n = 5,950) and White (n = 3,469) residents of a geographically defined urban community were randomly split into exploratory and confirmatory subgroups. A global measure of cognition was derived from 4 brief performance tests, and potential correlates of cognition (candidates) were selected from demographic, health-related, and experiential measures. In the exploratory subgroup, using a stepwise search algorithm, we examined the cognitive difference by race and then allowed candidate measures and Race × Candidate Measure interactions to enter the model.

RESULTS

The cognitive score in the exploratory subgroup (M = 0.257, SD = 0.714) was a mean of 0.403 unit lower in Black persons than White persons (SE = 0.021, p < .001), and race accounted for 7% of cognitive variability. After the candidate selection process, 16 measures were retained, including 12 candidate measures and the 2-way interactions of race with education, age, reading/cognitive activity, and neuroticism. In this model, which accounted for 45% of the variability in global cognition, race was no longer associated with global cognition (coefficient = 0.012, SE = 0.110, p = .912). Findings were replicated in the confirmatory subgroup.

CONCLUSION

These cross-sectional analyses suggest that consideration of demographic, health-related, and experiential factors greatly attenuates racial differences in late-life level of cognition. (PsycINFO Database Record

Brain Aging in African-Americans: The Atherosclerosis Risk in Communities (ARIC) Experience

Reported rates of dementia differ by race, although most studies have not focused on carefully measured outcomes, confounding by education or other demographic factors, nor have they studied other outcomes other than dementia. In this review we will discuss the experience in the Atherosclerosis Risk in Communities (ARIC) study evaluating racial disparities relating to stroke, subclinical brain infarction, leukoaraiosis, as well as cognitive change and dementia. ARIC is a biracial cohort of 15,792 participants from four U.S. communities, initially recruited in 1987-1989, and seen at a total of 5 in-person visits (most recently seen in 2011-2013) with annual follow-up phone calls. We will provide evidence from ARIC studies that disproportionate rates of vascular risk factors explain at least some of these observed disparities by race, but particular risk factors, including diabetes, may differentially affect the brain in African-American versus white participants. In addition, we will review some of the disparities by race in studies focusing on the genetics of stroke, small vessel disease, and dementia.

Memory and executive functions in persons with type 2 diabetes: a meta-analysis

Literature suggests that persons with type 2 diabetes mellitus (T2DM) are at risk for cognitive impairment, hence dementia. Common domains reported to be affected in those with T2DM are memory and executive functions. The extent of influence of T2DM on these domains has varied among studies. A systematic review and meta-analysis was carried out to understand whether sub-domains contributed to the variations observed in published research. We searched 'PubMed', 'ScienceDirect', 'SciVerseHub', 'Psychinfo', 'Proquest' 'Ebsco' and 'J-gate Plus' databases for published studies on cognition and T2DM among persons aged 50 years and older. Memory, executive functions and processing speed domain and sub-domain scores were extracted; effect sizes (Cohen's d) were calculated and analysed. Eight hundred seventeen articles were found. After various levels of filtering, 15 articles met the inclusion criteria for quantitative analyses. The analyses indicated that in comparison to controls, persons with T2DM showed decrements in episodic memory (d = -0.51), logical memory (d = -0.24), sub-domain of executive functions which included phonemic fluency (d = -0.35) and cognitive flexibility (d = 0.52), and speed of processing (d = -0.22). We found no difference in the sub-domains of verbal short-term memory and working memory. The meta-analysis revealed a detrimental effect of T2DM on cognitive sub-domains, namely, episodic memory and cognitive flexibility. There was a trend for the logical memory, phonemic fluency and processing speed to be affected. The analysis indicates that T2DM is a detrimental factor on certain cognitive sub-domains, rendering the person vulnerable to subsequent dementia. Copyright © 2016 John Wiley & Sons, Ltd.

Diabetes is associated with cerebrovascular but not Alzheimer's disease neuropathology

INTRODUCTION

The relationship of diabetes to specific neuropathologic causes of dementia is incompletely understood.

METHODS

We used logistic regression to evaluate the association between diabetes and infarcts, Braak neurofibrillary tangle stage, and neuritic plaque score in 2365 autopsied persons. In a subset of >1300 persons with available cognitive data, we examined the association between diabetes and cognition using Poisson regression.

RESULTS

Diabetes increased odds of brain infarcts (odds ratio [OR] = 1.57, P < .0001), specifically lacunes (OR = 1.71, P < .0001), but not Alzheimer's disease neuropathology. Diabetes plus infarcts was associated with lower cognitive scores at end of life than infarcts or diabetes alone, and diabetes plus high level of Alzheimer's neuropathologic changes was associated with lower mini-mental state examination scores than the pathology alone.

DISCUSSION

This study supports the conclusions that diabetes increases the risk of cerebrovascular but not Alzheimer's disease pathology, and at least some of diabetes' relationship to cognitive impairment may be modified by neuropathology.

Change in Cognitive Abilities in Older Latinos

The aim of this study was to compare patterns of cognitive decline in older Latinos and non-Latinos. At annual intervals for a mean of 5.7 years, older Latino (n=104) and non-Latino (n=104) persons of equivalent age, education, and race completed a battery of 17 cognitive tests from which previously established composite measures of episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability were derived. In analyses adjusted for age, sex, and education, performance declined over time in each cognitive domain, but there were no ethnic group differences in initial level of function or annual rate of decline. There was evidence of retest learning following the baseline evaluation, but neither the magnitude nor duration of the effect was related to Latino ethnicity, and eliminating the first two evaluations, during which much of retest learning occurred, did not affect ethnic group comparisons. Compared to the non-Latino group, the Latino group had more diabetes (38.5% vs. 25.0; χ2[1]=4.4; p=.037), fewer histories of smoking (24.0% vs. 39.4%, χ2[1]=5.7; p=.017), and lower childhood household socioeconomic level (-0.410 vs. -0.045, t[185.0]=3.1; p=.002), but controlling for these factors did not affect results. Trajectories of cognitive aging in different abilities are similar in Latino and non-Latino individuals of equivalent age, education, and race. (JINS, 2016, 22, 58-65).

Executive Function in Adults With Type 2 Diabetes: A Meta-Analytic Review

OBJECTIVE

To examine the extent to which Type 2 diabetes mellitus (T2DM) is associated with impairments in executive function (EF).

METHODS

Medline, PsychoInfo, and Scopus databases and published references were used to identify articles examining the association between T2DM status (case versus control) and EF decrements. Results from studies were converted to standardized mean differences and compared using random-effects models. Moderator analysis was conducted for age, sex, and diabetes duration using maximum likelihood estimation.

RESULTS

Sixty studies (59 articles) including 9815 individuals with T2DM and 69,254 controls were included. Findings indicated a small but reliable association between T2DM status and EF decrements (d = -0.248, p < .001), observed across all aspects of EF examined: verbal fluency, mental flexibility, inhibition, working memory, and attention. Disease duration significantly moderated the effect of T2DM status on EF.

CONCLUSIONS

T2DM is associated with a mild-to-moderate EF decrements. Such decrements are stronger among those with shorter disease duration.

Depressive symptoms and cognitive decline in older african americans: two scales and their factors

OBJECTIVE

Depressive symptoms are common in older adults, and researchers have explored the possibility of a link between depressive symptoms and cognitive decline, with mixed results. Most studies use total score of the Center for Epidemiological Studies Depression Scale (CES-D) with predominately non-Hispanic white participants. We sought to examine the relationship between the four factors of the CES-D and cognitive decline in older African Americans. Generalizability was determined using the Geriatric Depression Scale (GDS) and its factors.

METHODS

Participants without dementia from the Minority Aging Research Study (N = 298, mean age: 74 ± 5.68) underwent annual clinical evaluations (mean years: 5 ± 1.9), including depression assessment and cognitive testing, from which global and specific measures were derived. Cognitive decline was examined with linear mixed models adjusted for demographic variables and indicators of vascular risk.

RESULTS

Total CES-D score was not related to baseline cognition or change over time, whereas total GDS score was related to decline in semantic and working memory. In examining CES-D factors, lack of positive affect (e.g., anhedonia) was related to decline in global cognition, episodic memory, and perceptual speed. Similarly for the GDS, anhedonia was associated with decline in semantic memory, and increased negative affect was associated with decline in global cognition and episodic, semantic, and working memory.

CONCLUSION

Results suggest that depressive symptoms, particularly anhedonia and negative affect, are related to cognitive decline in older African Americans.

Cognitive aging in older Black and White persons

During a mean of 5.2 years of annual follow-up, older Black (n = 647) and White (n = 647) persons of equivalent age and education completed a battery of 17 cognitive tests from which composite measures of 5 abilities were derived. Baseline level of each ability was lower in the Black subgroup. Decline in episodic and working memory was not related to race. Decline in semantic memory, perceptual speed, and visuospatial ability was slower in Black persons than White persons, and in semantic memory and perceptual speed this effect was stronger in older than younger participants. Racial differences persisted after adjustment for retest effects. The results suggest subtle cognitive aging differences between Black persons and White persons.

Hyperactivation of working memory-related brain circuits in newly diagnosed middle-aged type 2 diabetics

Type 2 diabetes mellitus (T2DM) is well known for its adverse impacts on brain and cognition, which leads to multidimensional cognitive deficits and wildly spread cerebral structure abnormalities. However, existing literatures are mainly focused on patients with advanced age or extended T2DM duration. Therefore, it remains unclear whether and how brain function would be affected at the initial onset stage of T2DM in relatively younger population. In current study, twelve newly diagnosed middle-aged T2DM patients with no previous diabetic treatment history and twelve matched controls were recruited. Brain activations during a working memory task, the digit n-back paradigm (0-, 1- and 2-back), were obtained with functional magnetic resonance imaging and tested by repeated measures ANOVA. Whereas patients performed the n-back task comparably well as controls, significant load-by-group interactions of brain activation were found in the right dorsolateral prefrontal cortex (DLPFC), left middle/inferior frontal gyrus, and left parietal cortex, where patients exhibited hyperactivation in the 2-back, but not the 0-back or 1-back condition compared to controls. Furthermore, the severity of chronic hyperglycemia, estimated by glycosylated hemoglobin (HbA1c) level, was entered into partial correlational analyses with task-related brain activations, while controlling for the real-time influence of glucose, estimated by instant plasma glucose level measured before scanning. Significant positive correlations were found between HbA1c and brain activations in the anterior cingulate cortex and bilateral DLPFC only in patients. Taken together, these findings suggest there might be a compensatory mechanism due to brain inefficiency related to chronic hyperglycemia at the initial onset stage of T2DM.

Associations Between Diabetes and Cognitive Function in Socioeconomically Diverse African American and White Men and Women

OBJECTIVES

To examine whether race and poverty (income <125% of the federal poverty limit), modifies associations between diabetes and cognition in a biracial, urban-dwelling sample.

METHODS

Cross-sectional data for 2066 participants (mean age = 47.6 years, 56.8% women, 56.2% African American, 38.6% below poverty) from the first wave of the Healthy Aging in Neighborhoods of Diversity across the Life Span study were used for analyses. Eleven tests measured cognitive function. Interactions among diabetes, race, and poverty status with cognition were assessed in multiple regression analyses.

RESULTS

Significant interactions among diabetes, race, and poverty status were observed. Among African Americans below poverty, diabetic individuals performed lower than nondiabetic individuals on California Verbal Learning Test Free Recall Short Delay (z = -0.444 [0.123] versus z = -0.137 [0.045]) and Long Delay (z = -0.299 [0.123] versus z = -0.130 [0.045]), Digit Span Backward (z = -0.347 [0.109] versus z = -0.072 [0.041]), and the Brief Test of Attention (z = -0.452 [-0.099] versus z = -0.099 [0.047]), and higher on Category Fluency (z = 0.114 [0.117] versus z = -0.118 [0.044]). No consistent differences between diabetic and nondiabetic individuals were found for African American and white participants above poverty.

CONCLUSIONS

Diabetes was associated with poorer verbal memory, working memory, and attention among African Americans living in poverty. Diabetic African Americans below poverty may have increased risk of cognitive deficit at a younger age. Improving health literacy, doctor-patient communication, and multidisciplinary medical care for impoverished individuals may reduce differences. Additional research is needed to clarify mechanisms underlying these associations.

Glucose intolerance, insulin resistance, and pathological features of Alzheimer disease in the Baltimore Longitudinal Study of Aging

IMPORTANCE

Peripheral glucose homeostasis has been implicated in the pathogenesis of Alzheimer disease (AD). The relationship among diabetes mellitus, insulin, and AD is an important area of investigation. However, whether cognitive impairment seen in those with diabetes is mediated by excess pathological features of AD or other related abnormalities, such as vascular disease, remains unclear.

OBJECTIVE

To investigate the association between serial measures of glucose intolerance and insulin resistance and in vivo brain β-amyloid burden, measured with carbon 11–labeled Pittsburgh Compound B (11C-PiB), and AD pathology at autopsy.

DESIGN

Scores calculated from the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) and Braak criteria were correlated with measures of hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance in 197 participants who underwent autopsy after death and who had undergone 2 or more oral glucose tolerance tests (OGTT) using grouped analyses and a continuous mixed-models analysis. The same measures of glucose intolerance and insulin resistance were also correlated with brain 11C-PiB retention in an additional 53 living subjects from the Baltimore Longitudinal Study of Aging neuroimaging study.

SETTING

Prospective, serially assessed cohort of community-dwelling subjects.

PARTICIPANTS

Cohort 1 consisted of 197 participants enrolled in the Baltimore Longitudinal Study of Aging who had 2 or more OGTTs during life and a complete brain autopsy after death. Cohort 2 consisted of 53 living subjects who had 2 or more OGTTs and underwent brain 11C-PiB positron emission tomography.

EXPOSURES

Autopsy and 11C-PiB positron emission tomography.

MAIN OUTCOMES AND MEASURES

The correlation of brain markers of AD, including CERAD score, Braak score, and 11C-PiB retention, with serum markers of glucose homeostasis using grouped and continuous mixed-models analyses.

RESULTS

We found no significant correlations between measures of brain AD pathology or 11C-PiB β-amyloid load and glucose intolerance or insulin resistance in subjects who had a mean (SD) of 6.4 (3.2) OGTTs during 22.1 (8.0) years of follow-up. Thirty subjects with frank diabetes mellitus who received medications also had AD pathology scores that were similar to those of the cohort as a whole.

CONCLUSIONS AND RELEVANCE

In this prospective cohort with multiple assessments of glucose intolerance and insulin resistance, measures of glucose and insulin homeostasis are not associated with AD pathology and likely play little role in AD pathogenesis. Long-term therapeutic trials are important to elucidate this issue.

Apolipoprotein E and change in episodic memory in blacks and whites

BACKGROUND

Apolipoprotein E (APOE) ε4 is related to faster decline in episodic memory in Whites, but the relation is unknown in Blacks. The purpose of this study was to determine whether ε4 has a selective effect on decline in episodic memory in Blacks.

METHODS

Data are from two cohort studies with similar design. The sample consisted of 1,211 participants [28.4% Blacks, mean age = 78.6 years (SD = 7.4), education = 14.7 years (SD = 3.1)] without dementia at baseline, who underwent annual clinical evaluations for up to 6 years. Summary measures of 5 cognitive abilities were derived from 18 neuropsychological tests.

RESULTS

In mixed models that controlled for age, sex, education, and race, possession of ε4 (present in 32.9% of Blacks and 21.0% of Whites, p < 0.001) was related to faster decline in episodic memory and 4 other cognitive abilities (all p values <0.01). In separate models that examined the interaction of race and ε4 on decline, there was no significant difference between Blacks and Whites in the effect of ε4 on decline in episodic memory, perceptual speed, or visuospatial ability. By contrast, the effect of ε4 differed for semantic memory and working memory. Results were similar after adjusting for vascular conditions.

CONCLUSIONS

The results suggest that APOE ε4 is related to a faster rate of decline in episodic memory in Blacks similar to Whites. In addition, there were racial differences in the effect of ε4 in other cognitive abilities such that the ε4 allele was related to faster decline in semantic memory and working memory for Whites but not for Blacks.

Cognition in non-demented diabetic older adults

Evidence links diabetes mellitus to cognitive impairment and increased risk of Alzheimer's disease (AD) and suggests that insulin therapy improves cognition. With an increasing percentage of the US elderly population at high risk for diabetes and AD, the evidence of an association between diabetes and poor cognition in non-demented elderly may have implications for diagnosis, prevention and treatment of cognitive decline including AD. In our study, we hypothesized that diabetic elders with normal cognition would demonstrate poorer cognitive outcomes than non-diabetic elders and that diabetic elders receiving diabetes treatment would demonstrate better outcomes than those not receiving treatment. Data were evaluated from the National Alzheimer's Coordinating Center's Uniform Data Set (UDS). The UDS consists of clinical and neuropsychological assessments of a sample of elderly research subjects recruited from thirty-one Alzheimer's Disease Centers nationwide. The UDS provides a unique opportunity to study cognition in a nationally recruited sample with structured neuropsychological tests. We examined the impact of diabetes and diabetes treatment on cognitive measures in 3421 elderly research subjects from 2005-2007 with normal cognition. We performed linear regression analyses to compare cognitive scores between diabetic subjects and non-diabetic subjects. Diabetic subjects had lower scores than non-diabetic subjects including attention, psychomotor function and executive function, but no differences in memory or semantic memory language. There was no association between diabetes treatment and cognitive scores. These subtle but significant cognitive deficits in diabetic subjects compared to non-diabetic subjects may contribute to difficulty with compliance with complex diabetes medication regimens. A specific role of diabetes as a risk for cognitive impairment will require longitudinal study.

Overview and findings from the rush Memory and Aging Project

The Memory and Aging Project is a longitudinal, epidemiologic clinical-pathologic cohort study of common chronic conditions of aging with an emphasis on decline in cognitive and motor function and risk of Alzheimer's disease (AD). In this manuscript, we first summarize the study design and methods. Then, we present data on: (1) the relation of motor function to cognition, disability, and death; (2) the relation of risk factors to cognitive and motor outcomes, disability and death; (3) the relation of neuropathologic indices to cognitive outcomes; (4) the relation of risk factors to neuropathologic indices; and (5) additional study findings. The findings are discussed and contextualized.

Association between cognitive activity and cognitive function in older Hispanics

There is limited research on the association between participation in cognitively stimulating activity and cognitive function in older Hispanics. The main purpose of the present study was to explore whether frequency of cognitive activity and its association with cognitive function in Hispanics is comparable to that of non-Hispanics. In a multiethnic cohort of 1571 non-demented older adults, we assessed past and current cognitive activity, availability of cognitive resources in the home in childhood and middle age, and five domains of cognitive function. The measures of cognitive activity and cognitive resources had adequate reliability and validity in our subset of Hispanic participants (n = 81). Hispanics reported lower levels of education, lower frequency of cognitive activity and less cognitive resources than non-Hispanic White (n = 1102) and non-Hispanic Black (n = 388) participants. Despite these differences the strength of the association between cognitive activity and cognitive function was comparable across ethnic groups. Because Hispanics have lower frequency of cognitive activity, the benefit of cognitive activity to late life cognitive function may be potentially larger in this segment of the population. Thus, interventions aimed at increasing frequency of participation in cognitively stimulating activity may offer a potential target to reduce cognitive impairment in Hispanics.

Perceived discrimination and cognition in older African Americans

Existing evidence suggests that psychosocial stress is associated with cognitive impairment in older adults. Perceived discrimination is a persistent stressor in African Americans that has been associated with several adverse mental and physical health outcomes. To our knowledge, the association of discrimination with cognition in older African Americans has not been examined. In a cohort of 407 older African Americans without dementia (mean age = 72.9; SD = 6.4), we found that a higher level of perceived discrimination was related to poorer cognitive test performance, particularly episodic memory (estimate = -0.03; SE = .013; p < .05) and perceptual speed tests (estimate = -0.04; SE = .015; p < .05). The associations were unchanged after adjusting for demographics and vascular risk factors, but were attenuated after adjustment for depressive symptoms (Episodic memory estimate = -0.02; SE = 0.01; Perceptual speed estimate = -0.03; SE = 0.02; both p's = .06). The association between discrimination and several cognitive domains was modified by level of neuroticism. The results suggest that perceived discrimination may be associated with poorer cognitive function, but does not appear to be independent of depressive symptoms. (JINS, 2012, 18, 1-10).

The Minority Aging Research Study: ongoing efforts to obtain brain donation in African Americans without dementia

The Minority Aging Research Study (MARS) is a longitudinal, epidemiologic cohort study of decline in cognitive function and risk of Alzheimer's disease (AD) in older African Americans, with brain donation after death added as an optional component for those willing to consider organ donation. In this manuscript, we first summarize the study design and methods of MARS. We then provide details of ongoing efforts to achieve neuropathologic data on over 100 African Americans participating in MARS and in three other clinical-pathologic cohort studies at Rush University Medical Center. The results examine strategies for recruiting and consenting African Americans without dementia; (2) efforts to maintain high rates of follow-up participation; (3) strategies for achieving high rates of agreement to brain donation; and (4) the methodology of obtaining rapid brain autopsy at death. The implications of these efforts are discussed.

Neuroprotection and neurodegeneration in Alzheimer's disease: role of cardiovascular disease risk factors, implications for dementia rates, and prevention with aerobic exercise in african americans

Prevalence of Alzheimer's disease (AD) will reach epidemic proportions in the United States and worldwide in the coming decades, and with substantially higher rates in African Americans (AAs) than in Whites. Older age, family history, low levels of education, and ɛ4 allele of the apolipoprotein E (APOE) gene are recognized risk factors for the neurodegeneration in AD and related disorders. In AAs, the contributions of APOE gene to AD risk continue to engender a considerable debate. In addition to the established role of cardiovascular disease (CVD) risk in vascular dementia, it is now believed that CVD risk and its endophenotype may directly comediate AD phenotype. Given the pleiotropic effects of APOE on CVD and AD risks, the higher rates of CVD risks in AAs than in Whites, it is likely that CVD risks contribute to the disproportionately higher rates of AD in AAs. Though the advantageous effects of aerobic exercise on cognition is increasingly recognized, this evidence is hardly definitive, and data on AAs is lacking. In this paper, we will discuss the roles of CVD risk factors in the development of AD and related dementias, the susceptibility of these risk factors to physiologic adaptation, and fitness-related improvements in cognitive function. Its relevance to AD prevention in AAs is emphasized.

Life space and risk of Alzheimer disease, mild cognitive impairment, and cognitive decline in old age

OBJECTIVE

To test the hypothesis that a constricted life space, the extent of movement through the environment covered during daily functioning, is associated with increased risk of incident Alzheimer disease (AD), increased risk of mild cognitive impairment (MCI), and more rapid cognitive decline in older adults.

DESIGN

Two prospective cohort studies.

SETTING

Retirement communities, community-based organizations, churches, and senior subsidized housing facilities across the Chicago metropolitan area.

PARTICIPANTS

A total of 1,294 community-dwelling elders without baseline clinical dementia.

MAIN OUTCOME MEASURES

Detailed annual clinical evaluation to diagnose incident AD and MCI, and document change in cognitive function.

RESULTS

During a mean (SD) follow-up of 4.4 (1.7) years, 180 persons developed AD. In a proportional hazards model controlling for age, sex, race, and education, a more constricted life space was associated with an increased risk of AD (hazard ratio = 1.21, confidence interval: 1.08-1.36). A person with a life space constricted to their home was almost twice as likely to develop AD than a person with the largest life space (out of town). The association did not vary along demographic lines and persisted after the addition of terms for performance-based physical function, disability, depressive symptoms, social network size, vascular disease burden, and vascular risk factors. The association remained consistent after excluding persons with MCI at baseline and who developed AD in the first 2 years of observation. A constricted life space was also associated with an increased risk of MCI (hazard ratio = 1.17, confidence interval: 1.06-1.28), and a more rapid rate of global cognitive decline (estimate: -0.012, standard error: 0.003, t[5033] = -3.58, p <0.001).

CONCLUSIONS

A constricted life space is associated with increased risk of AD, MCI, and cognitive decline among older persons.

Loss of motor function in preclinical Alzheimer's disease

Accumulating evidence suggests that Alzheimer's disease (AD) has a long preclinical phase, during which time its characteristic pathology accumulates and patient function declines, but symptoms are insufficient to warrant a clinical diagnosis of dementia. There have been increasing reports of noncognitive symptoms, including loss of motor function, reported to be associated with incident AD. To understand the link between motor function and preclinical AD, this article examines: our understanding of motor function and its clinical assessment in cohort studies; the relationship of motor function and loss of cognition in older persons; risk factors for cognitive and motor decline; and the relation of post-mortem indices of AD and motor function prior to death. Together, these data suggest that age-related cognitive and motor decline may share a common causation. Furthermore, individuals with a clinical diagnosis of AD may represent the 'tip of the iceberg', since AD pathology may also account for a substantial proportion of cognitive and motor dysfunction currently considered 'normal aging' in older persons without dementia. Thus, AD may have a much larger impact on the health and wellbeing of our aging population.

High normal fasting blood glucose is associated with dementia in Chinese elderly

BACKGROUND

Diabetes is a risk factor for mild cognitive impairment (MCI) and dementia. However, the association between high normal fasting blood glucose (FBG) and dementia has not been studied.

METHODS

Polytomous logistic regression was used to assess the association of dementia and MCI with FBG in an age- and sex-matched sample of 32 dementia patients, 27 amnestic MCI (aMCI) patients, and 31 normal controls (NC). Analyses were repeated for those with normal FBG. Correlations between FBG and cognitive test scores were obtained.

RESULTS

Controlling for age, gender, education, body mass index, Hachinski Ischemic Score, magnetic resonance imaging (MRI) stroke, and normalized brain, hippocampal, and white matter hyperintensity MRI volumes; higher FBG was associated with dementia versus aMCI status (OR = 3.13; 95% CI, 1.28-7.69). This association remained (OR = 7.75; 95% CI, 1.10-55.56) when analyses were restricted to subjects with normal FBG. When dementia patients were compared with NC adjusting for age, gender, and education, a significant association with FBG also was seen (OR = 1.83; 95% CI, 1.09-3.08), but it was lost when vascular covariates were added to the model. FBG was not associated with aMCI status versus NC. Higher FBG was correlated with poorer performance on the Trailmaking Test Part B (P = .003). The percentage of dementia patients with high normal FBG (90%) was significantly higher than that of aMCI patients with high normal FBG (32.9%) (χ(2) = 13.9, P < .001).

CONCLUSIONS

Higher FBG was associated with dementia (vs. aMCI) independent of vascular risk factors and MRI indicators of vascular disease, and remained a significant risk factor when analyses were restricted to subjects with normal FBG. The results of this cross-sectional study suggest that a high normal level of FBG may be a risk factor for dementia.

Explaining differences in episodic memory performance among older African Americans and Whites: the roles of factors related to cognitive reserve and test bias

Older African Americans tend to perform poorly in comparison with older Whites on episodic memory tests. Observed group differences may reflect some combination of biological differences, measurement bias, and other confounding factors that differ across groups. Cognitive reserve refers to the hypothesis that factors, such as years of education, cognitive activity, and socioeconomic status, promote brain resilience in the face of pathological threats to brain integrity in late life. Educational quality, measured by reading test performance, has been postulated as an important aspect of cognitive reserve. Previous studies have not concurrently evaluated test bias and other explanations for observed differences between older African Americans and Whites. We combined data from two studies to address this question. We analyzed data from 273 African American and 720 White older adults. We assessed DIF using an item response theory/ordinal logistic regression approach. DIF and factors associated with cognitive reserve did not explain the relationship between race, and age- and sex-adjusted episodic memory test performance. However, reading level did explain this relationship. The results reinforce the importance of considering education quality, as measured by reading level, when assessing cognition among diverse older adults.

Cognitive function is associated with the development of mobility impairments in community-dwelling elders

OBJECTIVE

To examine the association of cognitive function with the risk of incident mobility impairments and the rate of declining mobility in older adults.

DESIGN

Prospective, observational cohort study.

SETTING

Retirement communities across metropolitan Chicago.

PARTICIPANTS

A total of 1,154 ambulatory elders from two longitudinal studies without baseline clinical dementia or history of stroke or Parkinson disease.

MEASUREMENTS

All participants underwent baseline cognitive testing and annual mobility examinations. Mobility impairments were based on annual timed walking performance. A composite mobility measure, which summarized gait and balance measures, was used to examine the annual rate of mobility change.

RESULTS

During follow-up of 4.5 years, 423 of 836 (50.6%) participants developed impaired mobility. In a proportional hazards model controlled for age, sex, education, and race, each 1-unit higher level of baseline global cognition was associated with a reduction to about half in the risk of mobility impairments (hazard ratio = 0.51, 95% confidence interval: 0.40-0.66) and was similar to a participant being about 13 years younger at baseline. These results did not vary by sex or race and were unchanged in analyses controlling for body mass index, physical activity, vascular diseases, and risk factors. The level of cognition in five different cognitive abilities was also related to incident mobility impairment. Cognition showed similar associations with incident loss of the ability to ambulate. Linear mixed-effects models showed that global cognition at baseline was associated with the rate of declining mobility.

CONCLUSIONS

Among ambulatory elders, cognition is associated with incident mobility impairment and mobility decline.