Systemic Inflammation Is Associated With Longitudinal Changes in Cognitive Performance Among Urban Adults

Coronavirus disease 2019 and its impact on the cognition of older adults: Unraveling the role of inflammation

Background

The Coronavirus Disease 2019 (COVID-19) pandemic significantly impacted the older adult population globally. This study aimed to investigate cognitive function and its relationship with inflammation in older COVID-19 survivors over a three-month follow-up to address concerns about cognitive impairment and its risk factors.

Methods

In this descriptive-analytical study, 177 hospitalized COVID-19 patients aged >60 were assessed from July 2021 to February 2022. Psychiatric, global cognitive assessments and activities of daily living were conducted at discharge, 1 month, and 3 months post-discharge. Statistical analyses were conducted using SPSS Version 24. The evolution of cognitive status over time was evaluated using the Repeated Measures Test. The study probed into the association between inflammatory markers and cognitive function through the Pearson correlation test and the Mann-Whitney U test. Additionally, the link between anxiety/depression and cognitive performance was examined using the Pearson correlation.

Results

Results indicated that higher levels of C-reactive protein (CRP), D-dimer, and Lactate Dehydrogenase (LDH) were correlated to reduced cognitive performance. Conversely, Erythrocyte Sedimentation Rate (ESR) and Creatine Phosphokinase (CPK) did not exhibit a significant relationship with cognitive scores. A positive correlation was observed between improved cognitive function (reflected by higher GPCOG scores) and lower levels of anxiety and depression (indicated by lower scores on the Hospital Anxiety and Depression Scale). Over the study period, cognitive function and anxiety scores showed an upward trend, whereas symptoms of depression and challenges in daily activities remained consistent.

Conclusions

The study highlights the enduring effects and detrimental role of inflammation on overall cognitive abilities among older survivors of COVID-19. It underscores the urgent need for specialized interventions and rehabilitative strategies to facilitate sustained cognitive recuperation among these individuals.

Systemic Biological Mechanisms of Neurocognitive Dysfunction in Long-Term Survivors of Childhood Hodgkin Lymphoma

PURPOSE

Hodgkin lymphoma (HL) survivors experience neurocognitive impairment despite receiving no central nervous system-directed therapy, though little is known about the underlying mechanisms.

EXPERIMENTAL DESIGN

HL survivors (n = 197) and age-, sex- and race/ethnicity frequency-matched community controls (n = 199) underwent standardized neurocognitive testing, and serum collection. Luminex multiplex or ELISA assays measured markers of inflammation and oxidative stress. Linear regression models compared biomarker concentrations between survivors and controls and with neurocognitive outcomes, adjusting for age, sex, race, body mass index, anti-inflammatory medication, and recent infections.

RESULTS

HL survivors [mean (SD) current age 36 (8) years, 22 (8) years after diagnosis] demonstrated higher concentrations of interleukin-6 (IL6), high-sensitivity c-reactive protein (hs-CRP), oxidized low-density lipoprotein, and glutathione peroxidase (GPx), compared with controls (P's < 0.001). Among survivors, higher concentrations of IL6 were associated with worse visuomotor processing speed (P = 0.046). hs-CRP ≥3 mg/L was associated with worse attention, processing speed, memory, and executive function (P's < 0.05). Higher concentrations of malondialdehyde were associated with worse focused attention and visual processing speed (P's < 0.05). Homocysteine was associated with worse short-term recall (P = 0.008). None of these associations were statistically significant among controls. Among survivors, hs-CRP partially mediated associations between cardiovascular or endocrine conditions and visual processing speed, whereas IL6 partially mediated associations between pulmonary conditions and visuomotor processing speed.

CONCLUSIONS

Neurocognitive function in long-term survivors of HL appears to be associated with inflammation and oxidative stress, both representing potential targets for future intervention trials.

Understanding the health effects of caregiving stress: New directions in molecular aging

Dementia caregiving has been linked to multiple health risks, including infectious illness, depression, anxiety, immune dysregulation, weakened vaccine responses, slow wound healing, hypertension, cardiovascular disease, metabolic syndrome, diabetes, frailty, cognitive decline, and reduced structural and functional integrity of the brain. The sustained overproduction of proinflammatory cytokines is a key pathway behind many of these risks. However, contrasting findings suggest that some forms of caregiving may have beneficial effects, such as maintaining caregivers' health and providing a sense of meaning and purpose which, in turn, may contribute to lower rates of functional decline and mortality. The current review synthesizes these disparate literatures, identifies methodological sources of discrepancy, and integrates caregiver research with work on aging biomarkers to propose a research agenda that traces the mechanistic pathways of caregivers' health trajectories with a focus on the unique stressors facing spousal caregivers as compared to other informal caregivers. Combined with a focus on psychosocial moderators and mechanisms, studies using state-of-the-art molecular aging biomarkers such as telomere length, p16INK4a, and epigenetic age could help to reconcile mixed literature on caregiving's sequelae by determining whether and under what conditions caregiving-related experiences contribute to faster aging, in part through inflammatory biology. The biomarkers predict morbidity and mortality, and each contributes non-redundant information about age-related molecular changes -together painting a more complete picture of biological aging. Indeed, assessing changes in these biopsychosocial mechanisms over time would help to clarify the dynamic relationships between caregiving experiences, psychological states, immune function, and aging.

C-Reactive protein and cognition: Mediation analyses with brain morphology in the UK Biobank

Cognitive impairments and abnormal immune activity are both associated with various clinical disorders. The association between C-Reactive protein (CRP), a marker associated with inflammation, and cognitive performance remains unclear. Further, mechanisms potentially linking CRP to cognition are not yet established. Brain structure may well mediate this relationship: immune processes play crucial roles in shaping and maintaining brain structure, with brain structure and function driving cognition. The United Kingdom Biobank (UKBB) is a large cohort study with extensive assessments, including high-sensitivity serum CRP levels, brain imaging, and various cognitive tasks. With data from 39,200 UKBB participants, we aimed first to determine the relationship between CRP and cognitive performance, and second, to assess metrics of brain morphology as potential mediators in this relationship. Participants were aged 40 to 70 at initial assessment and were mostly Caucasian. After accounting for potential covariates (e.g., age, sex, medical diagnoses, use of selective-serotonin reuptake inhibitors), we found CRP levels to have small, negative associations with fluid intelligence (b = -0.03, 95%CI[-0.05,-0.02], t(14381) = -3.62, p_cor = .004), and numeric memory (b = -0.03, 95%CI[-0.05,-0.01], t(14366) = -3.31, p_cor = .007). We found no evidence of brain morphology mediating these relationships (all |ab| < 0.001, all p_cor > .55). Our findings from this large sample suggest that serum-assessed CRP is of marginal importance for cognitive performance in mid-to-late aged Caucasians; the small effect sizes of statistically significant associations provide context to previous inconsistent results. The seeming lack of involvement of brain morphology suggests that other brain metrics (e.g., connectivity, functional activation) may be more pertinent to this relationship. Future work should also consider CRP levels measured in the central nervous system and/or other cytokines that may better predict cognitive performance in this population.

Inflammation and cognition in severe mental illness: patterns of covariation and subgroups

A potential relationship between dysregulation of immune/inflammatory pathways and cognitive impairment has been suggested in severe mental illnesses (SMI), such as schizophrenia (SZ) and bipolar (BD) spectrum disorders. However, multivariate relationships between peripheral inflammatory/immune-related markers and cognitive domains are unclear, and many studies do not account for inter-individual variance in both cognitive functioning and inflammatory/immune status. This study aimed to investigate covariance patterns between inflammatory/immune-related markers and cognitive domains and further elucidate heterogeneity in a large SMI and healthy control (HC) cohort (SZ = 343, BD = 289, HC = 770). We applied canonical correlation analysis (CCA) to identify modes of maximum covariation between a comprehensive selection of cognitive domains and inflammatory/immune markers. We found that poor verbal learning and psychomotor processing speed was associated with higher levels of interleukin-18 system cytokines and beta defensin 2, reflecting enhanced activation of innate immunity, a pattern augmented in SMI compared to HC. Applying hierarchical clustering on covariance patterns identified by the CCA revealed a high cognition-low immune dysregulation subgroup with predominantly HC (24% SZ, 45% BD, 74% HC) and a low cognition-high immune dysregulation subgroup predominantly consisting of SMI patients (76% SZ, 55% BD, 26% HC). These subgroups differed in IQ, years of education, age, CRP, BMI (all groups), level of functioning, symptoms and defined daily dose (DDD) of antipsychotics (SMI cohort). Our findings suggest a link between cognitive impairment and innate immune dysregulation in a subset of individuals with severe mental illness.

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

Background

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

Methods

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

Results

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

Conclusion

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

The association between total cholesterol and cognitive impairment in chronic obstructive pulmonary disease patients

AIM

Chronic obstructive pulmonary disease (COPD) is primarily a respiratory system disorder associated with extrapulmonary conditions. Cognitive impairment (CoI) is very common among COPD patients This study sought to investigate the association between CoI and clinical parameters, inflammatory markers and lipid profiles in a COPD patient population.

METHODS

The study population included 111 stable COPD patients. COPD was diagnosed according to Global Initiative for Chronic Obstructive Lung Disease guideline. Total complete blood count test and biochemical measurements including lipid profile were performed. Afterwards, all patients underwent neuropsychological assessment including Hospital Anxiety and Depression Scale (HADS), Pittsburgh Sleep Quality Index and Montreal Cognitive Assessment (MoCA) tests.

RESULTS

The patients were categorized into two groups according to their MoCA test score: MoCA score ≤ 21 (CoI) (n = 69) and MoCA score > 21 (normal cognition) (n = 42). Total cholesterol (TC) levels were significantly lower in patients with CoI compared to patients with normal cognition. Inflammation related parameters including C-reactive protein were similar among groups. Multivariate logistic regression analysis yielded education, HADS score and TC (OR:1.02, 95% CI:1.00-1.04, p = 0.025) as independent predictors of MoCA score.

CONCLUSION

TC independently associates with CoI in COPD patients. There is comparable inflammatory status in COPD patients with CoI compared to COPD patients with normal cognition.

Curcumin attenuates memory impairments and long-term potentiation deficits by damping hippocampal inflammatory cytokines in lipopolysaccharide-challenged rats

Neuroinflammation is a key pathological event triggering neurodegenerative process, resulting in neurologic sequelae. Curcumin (cur) has recently received increasing attention due to its anti-inflammatory properties. Therefore, we investigated the protective effects of curcumin on lipopolysaccharide (LPS)-induced memory impairments, long-term potentiation (LTP) deficits, hippocampal inflammatory cytokines, and neuronal loss in male rats. Rats were randomly divided into four groups as follows: (1) Vehicle; (2) cur; (3) LPS; and (4) cur/LPS. Following curcumin pretreatment (50 mg/kg, per oral via gavage, 14 consecutive days), animals received a single dose of LPS (1 mg/kg, intraperitoneally) or saline. Twenty-four hours after LPS/or saline administration, passive avoidance test (PAT), hippocampal LTP, inflammatory cytokines (TNFα, IL-1β), and neuronal loss were assessed in hippocampal tissue of rats. Our results indicated that pretreatment with curcumin in LPS-challenged rats attenuates memory impairment in PAT, which was accompanied by significant increase in the field excitatory post-synaptic potential (fEPSP) slope and population spike (PS) amplitude. Hence, pretreatment with curcumin in LPS-treated rats decreased hippocampal concentration of tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β), as well as reduced neuronal loss in the hippocampal tissue. This study provide evidence that pretreatment with curcumin attenuates LPS-induced memory impairment and LTP deficiency, which may be partly related to the amelioration of inflammatory cytokines and neuronal loss in the hippocampal tissue.

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.

Protocol for a randomized controlled trial of mindfulness-based stress reduction to improve attentional control in older adults (HealthyAgers trial)

BACKGROUND

Mindfulness meditation is a form of mind-body intervention that has increasing scientific support for its ability to reduce age-related declines in cognitive functioning, improve affective health, and strengthen the neural circuitry supporting improved cognitive and affective health. However, the majority of existent studies have been pilot investigations with small sample sizes, limited follow-up data, and a lack of attention to expectancy effects. Here, we present the study design of a Phase I/II, efficacy trial-HealthyAgers trial-that examines the benefits of a manualized mindfulness-based stress reduction program in improving attentional control and reducing mind-wandering in older adults.

METHODS

One hundred fifty older adults (ages 65-85 years) will be randomized into one of two groups: an eight-week mindfulness program or an eight-week, placebo-controlled, lifestyle education program. Behavioral and neuroimaging assessments are conducted before and after the training. Participants are then invited to booster sessions once every three months for a period of 12 months with post-intervention follow-up assessments conducted at 6-months and 12-months. The primary outcomes for the study are behavioral measures of attentional control and mind-wandering. Additional, secondary outcomes include network strength in an a priori defined neuromarker of attentional control, fluid and everyday cognition, emotion regulation strategy use, and markers of inflammation.

DISCUSSION

This study will establish the efficacy of a group-based, low-cost mind-body intervention for the inter-related facets of attentional control and mind-wandering in older adults. Strengths of this study include a well-designed, placebo-controlled comparison group, use of web/mobile application to track study adherence, and longitudinal follow-up.

TRIAL REGISTRATION

Clinicaltrials.gov (# NCT03626532 ). Registered August 4, 2018.

Diminished Cellular Immunity and Executive Cognitive Functioning Among Middle-Aged and Elderly Adults

OBJECTIVE

Within the field of psychoneuroimmunology, much attention has been given to immune dysregulation and its impact on cognitive functioning. Some of this work has focused on the association between high levels of basal proinflammatory cytokines and poorer performance on measures of executive functioning; however, effect sizes have been quite small in human studies.

METHODS

We investigated whether Epstein-Barr virus (EBV) antibody titers, a marker of immune dysregulation related to cellular immunity, may be associated with executive functioning while also attempting to replicate prior studies using two markers of proinflammatory cytokine production (i.e., circulating and lipopolysaccharide [LPS]-stimulated cytokines [interleukin 6, interleukin 1β, interferon-γ]). A total of 71 community-dwelling adults (mean [standard deviation] age = 60.87 [6.26] years) who were seropositive for EBV infection participated in the study.

RESULTS

Findings indicated that greater EBV antibody titers were associated with poorer performance on measures of the executive functions of inhibition ( B = -2.36, standard error = 1.06, p = .028) and cognitive flexibility ( B = -2.89, standard error = 1.13, p = .013) when including circulating and LPS-stimulated cytokines and other relevant covariates (i.e., age, sex, and body mass index) in linear regression analyses. Neither circulating nor LPS-stimulated cytokines were associated with performance on the cognitive tasks in the regression analyses.

CONCLUSIONS

These results suggest that EBV antibody titers may be an indicator of immune dysregulation that is more relevant to executive functioning performance than either circulating or stimulated proinflammatory cytokines among community-dwelling adults.

Acute versus chronic inflammatory markers and cognition in older black adults: Results from the Minority Aging Research Study

Peripheral inflammation is elevated in older Black adults, an elevation which prior work has suggested may be due to chronic stress associated with systemic racism and related adverse cardiovascular health conditions. Inflammation is also involved in the pathogenic processes of dementia; however, limited (and mixed) results exist concerning inflammation and cognitive decline in Black adults. We characterized patterns of inflammation and their role in cognitive decline in 280 older Black adults (age = 72.99 ± 6.00 years; 69.6% female) from the Minority Aging Research Study (MARS) who were without dementia at baseline and followed between 2 and 15 years (mean = 9 years). Participants completed a blood draw at baseline and annual cognitive evaluations. Serum was assayed for 9 peripheral inflammatory markers; 19 neuropsychological test scores were used to create indices of global cognition and five cognitive domains. Principal component analysis with varimax rotation characterized patterns of inflammation with factor loadings > 0.6 per component contributing to two composite scores representing acute/upstream and chronic/downstream inflammation. These composites were used as separate predictors in linear mixed regression models to determine associations with level and change in cognition adjusting for relevant covariates. Higher baseline upstream/acute inflammation associated with lower baseline semantic memory (p = .040) and perceptual speed (p = .046); it was not related to cognitive decline. By contrast, higher baseline downstream/chronic inflammation associated with faster declines in global cognition (p = .010), episodic (p = .027) and working memory (p = .006); it was not related to baseline cognition. For older Black adults, chronic, but not acute, inflammation may be a risk factor for changes in cognition.

Different profiles of neurocognitive impairment in patients with hepatitis B and C virus infections

The direct impact of chronic hepatitis B and hepatitis C on neurocognition remains elusive due to the frequent comorbidities, and the domains of the neurocognitive functions affected have rarely been investigated comprehensively. We cross-sectionally assessed the neurocognitive functions of the individuals with chronic hepatitis B, chronic hepatitis C, treated chronic hepatitis C with a sustained virologic response, and their healthy control counterparts. Laboratory examinations were used to investigate the impact of inflammation on neurocognition, exclude the medical conditions that could interfere with neurocognition assessment, and assess liver function and fibrotic severity of the liver of the participants. This study found the detrimental impact of chronic hepatitis B on language and executive functions. In contrast, individuals with chronic hepatitis C showed deficits in executive functions, psychomotor speed, memory, and attention. Successful elimination of hepatitis C resulted in improved liver function, but not neuropsychological test performance. Moreover, erythrocyte sedimentation rate level was found to mediate the deficits in the attention of individuals with chronic hepatitis C. These results demonstrate the neurocognitive deficits and the difference in the profiles of neurocognitive deficits in individuals with chronic hepatitis B and chronic hepatitis C. Our study also provided results suggesting the mediation by systemic inflammation on the attention deficit in individuals with chronic hepatitis C.

The Relationships of Fibrinogen and C-Reactive Protein With Gait Performance: A 20-Year Longitudinal Study

Background

Gait speed, a central marker of aging, has been linked to various health outcomes, such as cognitive and physical functions in middle-aged adults. Although long-term systemic low-grade inflammation is considered a mechanism underlying a variety of aging-related risk factors, the longitudinal associations between inflammation markers and gait speed are yet to be fully investigated.

Objective

To explore the associations of CRP and fibrinogen levels, measured two decades ago, with gait speed among community dwelling adults, considering the contribution of cardio-metabolic factors and cognition.

Methods

Study participants took part in two phases of the of the “Kibbutzim Family Study” (i.e., Phase II, 1999–2000 and Phase III, 2017–2019). Blood samples collected in Phase II (baseline) were used to determine level of inflammatory markers. Gait speed was assessed under single-task (ST) and dual-task (DT) conditions in Phase III. Demographic, anthropometric and clinical data were collected in both phases. Linear regression models were used to assess the adjusted associations of inflammation and gait speed.

Results

A total of 373 individuals aged 34–99 (mean 64 ± 13 years) in Phase III were included in the study. Gait speed under ST was negatively associated with baseline levels of fibrinogen (b per standard deviation (SD) = −0.053, p = 0.0007) and CRP (b per SD = −0.043, p = 0.010), after adjusting for baseline and concurrent cardiometabolic risk factors. Accounting for executive functions, associations of fibrinogen with gait under ST were somewhat attenuated, yet associations remained statistically significant (p < 0.05). Associations with CRP were attenuated to the null. In contrast, there were no associations between inflammation markers and gait under DT.

Conclusion

Our findings demonstrate that in a sample including younger to older adults, higher systemic inflammatory activity was linked with gait 20 years later, beyond age and cardiometabolic health, and to a certain extent, beyond executive functions. Thus, systemic inflammation may serve as an early marker to identify individuals at risk for gait decline.

Higher buccal mitochondrial DNA and mitochondrial common deletion number are associated with markers of neurodegeneration and inflammation in cerebrospinal fluid

Human immunodeficiency virus (HIV) infection is potentially associated with premature aging, but demonstrating this is difficult due to a lack of reliable biomarkers. The mitochondrial (mt) DNA "common deletion" mutation (mtCDM) is a 4977-bp deletion associated with aging and neurodegenerative diseases. We examined how mtDNA and mtCDM correlate with markers of neurodegeneration and inflammation in people with and without HIV (PWH and PWOH). Data from 149 adults were combined from two projects involving PWH (n = 124) and PWOH (n = 25). We measured buccal mtDNA and mtCDM by digital droplet PCR and compared them to disease and demographic characteristics and soluble biomarkers in cerebrospinal fluid (CSF) and blood measured by immunoassay. Participants had a median age of 52 years, with 53% white and 81% men. Median mtDNA level was 1,332 copies/cell (IQR 1,201-1,493) and median mtCDM level was 0.36 copies × 102/cell (IQR 0.31-0.42); both were higher in PWH. In the best model adjusting for HIV status and demographics, higher mtDNA levels were associated with higher CSF amyloid-β 1-42 and 8-hydroxy-2'-deoxyguanosine and higher mtCDM levels were associated with higher plasma soluble tumor necrosis factor receptor II. The differences in mtDNA markers between PWH and PWOH support potential premature aging in PWH. Our findings suggest mtDNA changes in oral tissues may reflect CNS processes, allowing the use of inexpensive and easily accessible buccal biospecimens as a screening tool for CSF inflammation and neurodegeneration. Confirmatory and mechanistic studies on mt genome alterations by HIV and ART may identify interventions to prevent or treat neurodegenerative complications.

Can exercise training teach us how to treat Alzheimer's disease?

Alzheimer's disease (AD) is the most common cause of dementia and there is currently no cure. Novel approaches to treat AD and curb the rapidly increasing worldwide prevalence and costs of dementia are needed. Physical inactivity is a significant modifiable risk factor for AD, estimated to contribute to 12.7% of AD cases worldwide. Exercise interventions in humans and animals have shown beneficial effects of exercise on brain plasticity and cognitive functions. In animal studies, exercise also improved AD pathology. The mechanisms underlying these effects of exercise seem to be associated mainly with exercise performance or cardiorespiratory fitness. In addition, exercise-induced molecules of peripheral origin seem to play an important role. Since exercise affects the whole body, there likely is no single therapeutic target that could mimic all the benefits of exercise. However, systemic strategies may be a viable means to convey broad therapeutic effects in AD patients. Here, we review the potential of physical activity and exercise training in AD prevention and treatment, shining light on recently discovered underlying mechanisms and concluding with a view on future development of exercise-free treatment strategies for AD.

Systemic Inflammation and Cognitive Decrements in Patients With Stage B Heart Failure

OBJECTIVE

This study aimed to investigate the role of systemic inflammation in reduced cognitive functioning in patients with early-stage heart failure (HF) while determining associations with other cardiovascular risk factors.

METHODS

Patients with stage B HF (n = 270; mean [standard deviation] age = 66.1 [10.1] years) were examined cross-sectionally for relationships among cardiovascular disease (CVD) and psychological risk factors, C-reactive protein (CRP), and Montreal Cognitive Assessment (MoCA) scores. A subsample (n = 83) at high risk for stage C HF (B-type natriuretic peptide levels ≥65 pg/ml) were followed up for 12 months for relationships between CRP levels and cognitive function.

RESULTS

Baseline smoking (χ2 = 6.33), unmarried (χ2 = 12.0), hypertension (χ2 = 5.72), greater body mass index (d = 0.45), and physical fatigue (d = 0.25) were related to higher CRP levels (p values < .05). Cross-sectionally, CRP levels were negatively related to MoCA scores, beyond CVD (ΔR2 = 0.022, β = -0.170, p < .010) and psychological risk factors (ΔR2 = 0.016, β = 0.145, p < .027), and related to mild cognitive impairment criteria (odds ratio = 1.35, 95% confidence interval [CI] = 1.00-1.81, p = .046). Across 12 months, B-type natriuretic peptide high-risk patients with CRP levels ≥3 mg/L had lower MoCA scores (23.6; 95% CI = 22.4-24.8) than did patients with CRP levels <3 mg/L (25.4; 95% CI = 24.4-26.5; p = .024).

CONCLUSIONS

Patients with stage B HF and heightened CRP levels had greater cognitive impairment at baseline and follow-up, independent of CVD and potentially psychological risk factors. Low-grade systemic inflammation may be one mechanism involved in cognitive dysfunction at early stages of HF.

Inflammation mediates depression and generalized anxiety symptoms predicting executive function impairment after 18 years

INTRODUCTION

Scar theories propose that elevated depression and anxiety can predispose people to future decreased executive function (EF) via heightened inflammation across decades. However, more longitudinal (versus cross-sectional) research on this topic is needed.

OBJECTIVE

We thus investigated if increased major depressive disorder (MDD), generalized anxiety disorder (GAD), and panic disorder (PD) severity predicted EF decrement 18 years later via heightened inflammation.

METHOD

Community-dwelling adults participated in this study. Time 1 (T1) MDD, GAD, and PD severity (Composite International Diagnostic Interview-Short Form), T2 inflammation (interleukin-6, C-reactive protein, and fibrinogen blood levels concentration), and T2 and T3 EF (Brief Test of Adult Cognition by Telephone) were measured. The waves of assessment were spaced approximately 9 years apart. Structural equation modeling was conducted.

RESULTS

Higher T1 MDD and GAD (but not PD) severity forecasted elevated T2 inflammation (Cohen's d = 0.116-0.758). Greater T2 inflammation level predicted lower T3 EF following 9 years (d = -0.782--0.636). The T1 MDD-T3 EF and T1 GAD-T3 EF negative associations were mediated by T2 inflammation, and explained 38% and 19% of the relations, respectively. Direct effects of higher T1 GAD and MDD predicting lower T3 EF were also observed (d = -0.585--0.560). Significant effects remained after controlling for socio-demographic, lifestyle, medication use, various illness variables across time, and T2 EF.

CONCLUSIONS

Inflammation may be a mechanism explaining the T1 MDD-T3 EF and T1 GAD-T3 EF relations. Treatments that target inflammation, worry, and/or depression may prevent future EF decline.

Longitudinal associations between C-reactive protein and cognitive performance in normative cognitive ageing and dementia

BACKGROUND

systemic inflammation appears to play an important role in the pathogenesis and expression of Alzheimer's disease and other dementias. Previous research has found that elevated levels of serum C-reactive protein (CRP) is associated with poorer cognitive functioning and increased risk for dementia. However, most studies are limited by single CRP measurements, which fail to capture long-term inflammatory exposures or dynamic changes in inflammation and cognition which may occur across repeated measurements.

METHODS

using data from 3,563 older adults aged 65-101 from the Health and Retirement Study, we examined bivariate changes in CRP and cognition measured repeatedly over a 10-year follow-up. Bivariate multilevel models estimated the effect of time-varying CRP on cognition among cognitively healthy older adults and in a subset of 427 participants who reported incident dementia onset during the follow-up period.

RESULTS

in cognitively healthy participants, CRP was associated with lower level of cognitive functioning, but not rate of change over time. This effect was significant in participants under 80 years of age (b = -0.09, standard error (SE) = 0.05, P = 0.04), but not in older participants. In participants with incident dementia, those with higher CRP experienced smaller rates of cognitive decline, leading up to dementia diagnosis.

CONCLUSIONS

elevated levels of CRP predict poorer cognition and increased dementia risk in cognitively healthy adults under the age of 80. Conversely, increased CRP may confer protective effects on cognition in the prodromal stage of dementia.

Adulthood systemic inflammation accelerates the trajectory of age-related cognitive decline

In order to understand the long-term effects of systemic inflammation, it is important to distinguish inflammation-induced changes in baseline cognitive function from changes that interact with aging to influence the trajectory of cognitive decline. Lipopolysaccharide (LPS; 1 mg/kg) or vehicle was administered to young adult (6 months) male rats via intraperitoneal injections, once a week for 7 weeks. Longitudinal effects on cognitive decline were examined 6 and 12 months after the initial injections. Repeated LPS treatment, in adults, resulted in a long-term impairment in memory, examined in aged animals (age 18 months), but not in middle-age (age 12 months). At 12 months following injections, LPS treatment was associated with a decrease in N-methyl-D-aspartate receptor-mediated component of synaptic transmission and altered expression of genes linked to the synapse and to regulation of the response to inflammatory signals. The results of the current study suggest that the history of systemic inflammation is one component of environmental factors that contribute to the resilience or susceptibility to age-related brain changes and associated trajectory of cognitive decline.

Metabolic Syndrome Impairs Executive Function in Bipolar Disorder

Background: Metabolic syndrome (MetS) is more prevalent in individuals with bipolar disorder and has a negative impact on cognition, in particular on executive function, which is already impaired in individuals with bipolar disorder compared to healthy controls.

Methods: In a cross-sectional study, we compared 148 euthymic patients with bipolar disorder and 117 healthy controls in cognitive function depending on the diagnosis of MetS. A neuropsychological test battery was used including the Trail Making Test A/B, Stroop Color and Word Interference Test, the d2 Test of Attention Revised, and the California Verbal Learning Test. In addition, MetS variables as well as the defining variables waist circumference, serum triglyceride levels, high-density lipoprotein cholesterol levels, blood pressure, fasting glucose levels, and body mass index were compared between patients and controls. In addition, illness-related variables were associated with MetS in individuals with bipolar disorder.

Results: The prevalence of MetS in patients with bipolar disorder was higher than in controls (30.4 vs. 15.4%). Patients with bipolar disorder with MetS had impaired executive function compared to patients without MetS or healthy controls with and without MetS (p = 0.020). No MetS effects or interaction MetS × Group was found in attention/processing speed (p = 0.883) and verbal learning/memory (p = 0.373). Clinical variables (illness duration, suicidality, number of affective episodes, medication, age of onset, and history of psychosis) did not relate to MetS in bipolar disorder (p > 0.05).

Conclusion: Bipolar disorder comorbid with MetS bears additional risk for impaired executive function. Executive function includes action planning, inhibition, and impulse control and could play a critical role in keeping long-term goals in mind associated with gaining and maintaining a healthy weight.

Sarcopenia and Mild Cognitive Impairment in Older Adults from Six Low- and Middle-Income Countries

BACKGROUND

Little is known about the relationship between sarcopenia and mild cognitive impairment (MCI) in low- and middle-income countries (LMICs).

OBJECTIVE

This study aimed to investigate this association among community-dwelling adults aged≥65 years from six LMICs.

METHODS

Cross-sectional, nationally representative data from the Study on Global Ageing and Adult Health (SAGE) were analyzed. These data were obtained in China, Ghana, India, Mexico, Russia, and South Africa in 2007-2010. Participants were considered to have sarcopenia if they had low skeletal muscle mass (i.e., lower skeletal mass index) and a weak handgrip strength. MCI was defined using the National Institute on Aging-Alzheimer's Association criteria. Multivariable logistic regression analysis was conducted to assess associations.

RESULTS

The final analytical sample consisted of 12,912 individuals aged≥65 years with preservation in functional abilities without stroke (mean [standard deviation] age 72.2 [10.8] years; 45.2% males). The overall prevalence of sarcopenia and MCI were 11.3% and 18.1%, respectively. After adjusting for potential confounders, there was a positive association between sarcopenia and MCI in all countries (i.e., odds ratio [OR] > 1) with the exception of South Africa, and the overall estimate was OR = 1.60 (95% confidence interval [CI] = 1.32-1.93) with a low level of between-country heterogeneity (I2 = 0.0%).

CONCLUSION

There was a positive association between sarcopenia and MCI in this sample of older adults living in LMICs. Causality should be assessed in future longitudinal research, while the utility of sarcopenia as a marker of MCI should also be investigated.

Hepatic Encephalopathy: From Metabolic to Neurodegenerative

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome of both acute and chronic liver disease. As a metabolic disorder, HE is considered to be reversible and therefore is expected to resolve following the replacement of the diseased liver with a healthy liver. However, persisting neurological complications are observed in up to 47% of transplanted patients. Several retrospective studies have shown that patients with a history of HE, particularly overt-HE, had persistent neurological complications even after liver transplantation (LT). These enduring neurological conditions significantly affect patient's quality of life and continue to add to the economic burden of chronic liver disease on health care systems. This review discusses the journey of the brain through the progression of liver disease, entering the invasive surgical procedure of LT and the conditions associated with the post-transplant period. In particular, it will discuss the vulnerability of the HE brain to peri-operative factors and post-LT conditions which may explain non-resolved neurological impairment following LT. In addition, the review will provide evidence; (i) supporting overt-HE impacts on neurological complications post-LT; (ii) that overt-HE leads to permanent neuronal injury and (iii) the pathophysiological role of ammonia toxicity on astrocyte and neuronal injury/damage. Together, these findings will provide new insights on the underlying mechanisms leading to neurological complications post-LT.

Cystic fibrosis-related diabetes (CFRD) and cognitive function in adults with cystic fibrosis

BACKGROUND

Being able to function cognitively is imperative for successful achievement in school, working life, and disease self-management. Diabetes is known to cause changes in brain structure and long-term cognitive dysfunction. This work investigated cystic fibrosis-related diabetes (CFRD) as a mechanism for cognitive impairment in people with CF. It was hypothesised that cognition would be poorer in adults with CFRD than in those with CF without diabetes (CFND) or in healthy controls.

METHODS

Cognitive performance was assessed using the Cambridge Neuropsychological Test Automated Battery which provides a comprehensive cognitive assessment with tests mapping onto specific brain regions. Demographic, clinical and self-reported health data were documented for all participants. CF specific clinical variables were recorded for the two CF groups.

RESULTS

Ninety-eight people with CF (49CFRD,49CFND) and 49 healthy controls were recruited. People with CF demonstrated deficits in aspects of verbal and spatial memory, processing speed and cognitive flexibility compared with healthy controls, with all areas of the brain implicated. Those with CFRD had additional difficulties with higher-level processes known collectively as 'executive function', which demand greater cognitive load and recruit the prefrontal cortex. Compared with healthy controls, those with CFND and CFRD had an estimated 20% and up to 40% reduction in processing speed respectively.

CONCLUSION

Managing CF requires higher order executive function. Impairments may be sufficient to interfere with self-care and the ability to perform everyday tasks efficiently. At which point in the CF disease trajectory these difficulties begin, and what may attenuate them, has yet to be determined.

Inflammatory markers and imaging patterns of advanced brain aging in the general population

Inflammaging describes the complexity between low-grade chronic inflammation with the pathogenesis of brain aging and Alzheimer´s disease (AD). We aimed to find associations of inflammatory markers: i) white blood cell count (WBC), ii) high-sensitivity C-reactive protein (hs-CRP), and iii) fibrinogen with brain structures, sensitive neuroimaging markers of advanced brain aging and AD-like atrophy, and cognitive aging scores. We analyzed magnetic resonance imaging (MRI) scans of 2204 participants from the Study of Health in Pomerania-2 (SHIP-2) and SHIP-Trend (55.6% women, mean age 52.4±13.7 years). Associations of the inflammatory markers with specific brain signatures of brain aging (SPARE-BA), AD-like brain atrophy (SPARE-AD) and white matter disease (white matter hyperintensities volume (WMHV)) were investigated. Furthermore we explored their association with general brain structures including total brain volume (TBV), gray matter volume (GMV), and white matter volume (WMV), as well as cognitive scores (Nurnberger Age Inventory (NAI); Verbal Learning and Memory Test (VLMT). We adjusted for multiple vascular risk factors (VRF; e.g. smoking and blood pressure) and corresponding medication use to take their brain aging effects into account and corrected for false-discovery rate (FDR). Results:WBC was inversely associated with SPARE-BA (FDR-adjusted p=0.003), TBV (FDR-adjusted p=0.019) and GMV (FDR-adjusted p= 0.017). GMV was also inversely associated with hs-CRP (FDR-adjusted p=0.039) and fibrinogen (FDR-adjusted p=0.039). None of the inflammatory markers was associated with WMHV. Regression analysis also revealed a trend-level interaction between intake of antiinflammatory medication and hs-CRP with brain aging (SPARE-BA; FDR-adjusted p=0.062). Inflammatatory markers are associated with neuroimaging markers, with elevated WBC leading to significant acceleration in brain aging patterns but not with AD-like imaging structural changes. Given the overlap between accelerated brain aging and AD-like atrophy, increased WBC might be associated with global dementia symptoms due to this overlap in atrophy patterns. Elevated WBC may be not causal to preclinical AD dementia, but an accessory symptom of inflammaging. At population level, our results support the relevant roles of inflammatory markers on brain aging related atrophy.

Preoperative Microbiomes and Intestinal Barrier Function Can Differentiate Prodromal Alzheimer's Disease From Normal Neurocognition in Elderly Patients Scheduled to Undergo Orthopedic Surgery

Objective

Emerging evidence links perturbations in the microbiome to neurodegeneration in amnestic mild cognitive impairment (aMCI) and Alzheimer’s disease (AD) and to surgical stress. In this study, we attempted to identify preoperative differences intestinal microbiota (IM) and barrier function between pAD [prodromal AD: Subjective cognitive decline (SCD) and aMCI] patients and normal neurocognition (NC) patients. Additionally, the potential associations between IM and barrier function, inflammation, and the clinical characteristics of pAD were evaluated.

Design

Eighty elderly patients scheduled to undergo orthopedic surgery were consecutively enrolled and grouped as NC, SCD, and aMCI following neuropsychological assessment. IM was determined by 16S rRNA MiSeq sequencing, and PICRUSt was used to predict functional shifts in IM. Furthermore, we investigated the association between IM and plasma claudin-1, occludin, LPS, systemic inflammatory cytokines, neuropsychological assessment, and clinical characteristics.

Results

There was a lower Chao1 index in the SCD group (P = 0.004) and differences in beta diversity among the three groups (PCA: P = 0.026, PCoA: P= 0.004). The relative abundance of Bacteroidetes was higher in the SCD group (P = 0.016, P = 0.008), and Firmicutes were more enriched in the aMCI group than in the SCD group (P= 0.026). At the family level, the total abundance of Gram-negative bacteria was higher in the SCD group than in the aMCI group (P = 0.047), and the Christensenellaceae family was detected at lower levels in the SCD and aMCI groups than in the NC group (P= 0.039). At the genus level, the eleven short-chain fatty acid (SCFA)-producing bacteria exhibited differences among the three groups. PICRUSt analysis showed that the pathways involved in SCFA catabolism, biosynthesis, and adherent junctions were reduced in SCD patients, and lipid synthesis proteins were reduced in pAD patients. Meanwhile, elevated plasma LPS and CRP were observed in SCD patients, and higher plasma occludin in aMCI patients. The IM was correlated with plasma claudin-1, LPS, inflammatory factors, neuropsychological assessment, and clinical characteristics.

Conclusion

The intestines of SCD and aMCI patients preoperatively exhibited IM dysbiosis and barrier dysfunction, and elevated plasma LPS and CRP were observed in SCD patients.

Vitamin D status and its longitudinal association with changes in patterns of sleep among middle-aged urban adults

OBJECTIVE

We examined relationships of vitamin D status with over time changes in patterns of sleep in a longitudinal study of Whites and African-American urban middle-aged adults, while further testing effect modification by age group, sex and race and the potential roles of dietary and supplemental vitamin D.

METHODS

Data on 1,760 middle-aged participants in the Healthy Aging in Neighborhoods of Diversity Across the Life Span (HANDLS study: Age range at v₂: 33-71y, mean±SD:53.0±8.8, % women: 58.4%, % African-American:60.3%) were used, with complete baseline 25-hydroxyvitamin D [25(OH)D] serum concentration data, initial selected covariates and mediators, and initial and/or follow-up data on five sub-scales (sleep duration, daytime dysfunction, sleep disturbance, sleep latency and sleep quality) of the Pittsburgh Sleep Quality Index. Mean±SD time between initial and follow-up visits: 4.1±1.5 years. Time-interval multiple mixed-effects linear regression models were used.

RESULTS

Upon multiple testing adjustment, among Whites, initial 25(OH)D was associated with better sleep duration [25(OH)D × TIME γ±SE: -0.027±0.011, P=0.017] and sleep quality [25(OH)D × TIME γ±SE: -0.026±0.010, P=0.008] over time, with heterogeneity by race found for both relationships (P<0.05 for 25(OH)D × TIME × Race in the un-stratified model). These relationships remained unaltered after further adjustment for dietary and supplemental vitamin D, indicating that this association may be largely explained by sunlight exposure.

LIMITATIONS

Limitations included small sample size, selection bias, residual confounding and lack of objective sleep measures. Conclusions Vitamin D status, possibly through mechanisms involving sunlight exposure, was linked to a potential improvement in sleep duration and quality among White urban adults.

Cognitive dysfunction in young subjects with periodontal disease

Background

Periodontal disease is an inflammatory, dysbiotic condition. Studies have shown that in the elderly, periodontal disease was associated with cognitive dysfunction and Alzheimer’s disease.

Objective

To investigate whether young healthy subjects with periodontal disease have lower cognition compared to those without periodontal disease. The salivary cytokines (IL-1β, TNF-α) levels in relation to cognition were also tested.

Methods

In a monocenter, cross-sectional study, forty subjects [mean age (SD) = 34 (5) and 48% female] from western Romania were classified into periodontal disease conditions using radiographic assessment: 10 subjects had aggressive periodontitis (AGG_P), 20 chronic mild-moderate periodontitis (CR_P), and 10 no periodontitis (NL_P). Neuropsychological assessment performed by standardized neurologists and psychologist included Rey Auditory Verbal Learning Test (RAVLT), Montreal Cognitive Assessment test (MOCA), Mini-Mental State Examination (MMSE), and Prague tests. Salivary cytokines levels were determined by ELISA.

Results

RAVLT and MOCA delayed recall scores were lower in AGG_P group compared to NL_P and CR_P. The learning curve was also different with subjects with AGG_P showing reduced learning performance. Contrary to our hypothesis, salivary IL-1β associated with immediate but not delayed cognitive scores.

Conclusions

These results showed for the first time that subjects with AGG_P had cognitive dysfunction and IL-1β may play a role in this process.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-021-05115-3.

C-reactive protein and risk of cognitive decline: The REGARDS study

Markers of systemic inflammation are associated with increased risk of cognitive impairment, but it is unclear if they are associated with a faster rate of cognitive decline and whether this relationship differs by race. Our objective was to examine the association of baseline C-reaction protein (CRP) with cognitive decline among a large racially diverse cohort of older adults. Participants included 21,782 adults aged 45 and older (36% were Black, Mean age at baseline 64) from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study. CRP was measured at baseline and used as a continuous variable or a dichotomous grouping based on race-specific 90th percentile cutoffs. Cognitive measures of memory and verbal fluency were administered every 2 years for up to 12 years. Latent growth curve models evaluated the association of CRP on cognitive trajectories, adjusting for relevant demographic and health factors. We found that higher CRP was associated with worse memory (B = -.039, 95% CI [-.065,-.014]) and verbal fluency at baseline (B = -.195, 95% CI [-.219,-.170]), but not with rate of cognitive decline. After covariate adjustment, the association of CRP on memory was attenuated (B = -.005, 95% CI [-.031,-.021]). The association with verbal fluency at baseline, but not over time, remained (B = -.042, 95% CI [-.067,-.017]). Race did not modify the association between CRP and cognition. Findings suggest that levels of CRP at age 45+, are a marker of cognitive impairment but may not be suitable for risk prediction for cognitive decline.

Inflammation, Cognition, and White Matter in Older Adults: An Examination by Race

Objectives

Non-Latino Black adults have greater risk for Alzheimer’s dementia compared to non-Latino White adults, possibly due to factors disproportionally affecting Black adults including cardiovascular disease (CVD). Chronic peripheral inflammation is implicated in both Alzheimer’s dementia and CVD and is known to impact cognition and cerebral white matter, yet little work has examined these associations by race. This study examined associations between inflammation, cognition, and cerebral white matter generally, and by race.

Methods

Eighty-six non-demented older Black and White participants (age = 69.03; 50% female; 45% Black participants) underwent fasting venipuncture, cognitive testing, and MRI. Serum was assayed for interleukin-6 (IL-6), C-reactive protein (CRP), and interleukin 1-beta. Cognitive domains included memory, executive function, and attention/information processing. MRI measures included white matter hyperintensity volumes (WMH) and quantification of white matter integrity in areas outside WMHs via DTI-derived fractional anisotropy (FA) and mean diffusivity, as well as multi-component relaxometry derived myelin water fraction (MWF).

Results

Black and White participants did not differ on age, sex, or CVD risk. Separate linear regression models adjusting for relevant confounders revealed that higher IL-6 associated with lower executive function and higher CRP levels associated with lower FA and MWF. Stratified analyses revealed that these association were significant for Black participants only.

Discussion

These findings suggest that peripheral inflammation is inversely associated with select cognitive domains and white matter integrity (but not WMHs), particularly in older Black adults. It is important to consider race when investigating inflammatory associates of brain and behavior.

Discrimination and systemic inflammation: A critical review and synthesis

Exposure to discrimination or unfair treatment has emerged as an important risk factor for illness and disease that disproportionately affects racial and ethnic minorities. Discriminatory experiences may operate like other stressors in that they activate physiological responses that adversely affect the maintenance of homeostasis. Research suggests that inflammation plays a critical role in the pathophysiology of stress-related diseases. Recent findings on discrimination and inflammation are discussed. We highlight limitations in the current evidence and provide recommendations for future studies that seek to examine the association between discrimination and inflammation.

Association between anti-inflammatory interleukin-10 and executive function in African American women at risk for Alzheimer's disease

INTRODUCTION

African-Americans (AAs) are 64% more likely to be diagnosed with AD than non-Hispanic Whites. AAs with elevated AD biomarkers exhibit greater neurodegeneration in AD signature regions compared to non-Hispanic Whites with elevated AD biomarkers. This pilot trial examined whether normal or elevated plasma levels of interleukin (IL)-10 are associated with changes in executive function and short-term memory in AA women at risk for developing AD due to parental history.

METHOD

Observational study comparing groups with elevated and normal plasma IL-10 levels. Study included 31 AA women (age=58.9±8 years) with parental history of AD. Measures included inflammatory blood biomarkers, executive function and visuospatial short-term memory tests. Multivariate linear regression with adjustment for comorbidities, and Bonferroni corrections for multiple comparisons were used to compare groups. Effect sizes (Cohen's d) were generated. Using endpoints with moderate-large effects between groups, Pearson correlations determined associations between biomarker levels and cognitive performance.

RESULTS

The elevated IL-10 group performed worse on the Trail-Making Test proportional score ((B-A)/A) (effect size (d =-0.87 (-1.6, -.1)). Moderate effects with large confident intervals were noted in inhibition, set-switching, and body position spatial memory. Significant differences between groups in levels of other inflammatory markers were noted, including IL-7 (p=0.002) and interferon γ (p=0.02). IL-7 remained significant after Bonferroni correction. Correlation matrices revealed moderate-large, significant correlations (yet with wide confidence intervals) between levels of IL-10 and IL-9 with BPST total correct trials, and between interferon γ and delayed recall.

CONCLUSIONS

Interleukins may incite inflammation, leading to impaired aspects of executive function and short-term memory in this sample of African American women at risk for developing AD. This research provides effect sizes that will be used to power future research that will further investigate the relationship between inflammation, AD biomarkers, and cognitive function in an understudied population.

The association between systemic inflammation and cognitive performance in healthy adults

BACKGROUND

Several studies have indicated that mild systemic inflammation is associated with the risk of cognitive impairment. However, not every cognitive domain has been evaluated to have a correlation with peripheral inflammation in healthy individuals. Therefore, we aimed to investigate the association between C-reactive protein (CRP) as a marker of peripheral inflammation with various domains of cognition in healthy adults.

METHOD

This study consisted of 216 healthy native German adults (138 males and 78 females, mean age: 39.12 ± 20.19 years) from "Leipzig Study for Mind-Body-Emotion Interactions" (LEMON) database. After the initial assessment and conducting the cognitive battery, a blood sample was collected and CRP level was evaluated. Patients were categorized into three groups based on their CRP level. Subsequently, demographic and cognitive features were compared across three groups and to confirm the association between CRP level and cognitive performance, general linear models (GLM) were applied.

RESULTS

All California Verbal Learning Task (CVLT)-evaluated aspects of memory performance were inversely associated with CRP level, some of which remained significant after the adjustment for age, gender, education, smoking status and body mass index. Moreover, GLM analysis indicated that mean reaction time of the Test of Attentional Performance-Alertness (TAP-A) test (with and without signal) was also significantly associated with CRP level.

CONCLUSION

The current study indicated that healthy subjects with higher levels of CRP exhibit poorer performance in verbal learning memory and general wakefulness domains of cognition.

Differential Effect of Repeated Lipopolysaccharide Treatment and Aging on Hippocampal Function and Biomarkers of Hippocampal Senescence

Markers of brain aging and cognitive decline are thought to be influenced by peripheral inflammation. This study compared the effects of repeated lipopolysaccharide (LPS) treatment in young rats to age-related changes in hippocampal-dependent cognition and transcription. Young Fischer 344 X Brown Norway hybrid rats were given intraperitoneal injections once a week for 7 weeks with either LPS or vehicle. Older rats received a similar injection schedule of vehicle. Old vehicle and young LPS rats exhibited a delay-dependent impairment in spatial memory. Further, LPS treatment reduced the hippocampal CA3-CA1 synaptic response. RNA sequencing, performed on CA1, indicated an increase in genes linked to neuroinflammation in old vehicle and young LPS animals. In contrast to an age-related decrease in transcription of synaptic genes, young LPS animals exhibited increased expression of genes that support the growth and maintenance of synapses. We suggest that the increased expression of genes for growth and maintenance of synapses in young animals represents neuronal resilience/recovery in response to acute systemic inflammation. Thus, the results indicate that repeated LPS treatment does not completely recapitulate the aging phenotype for synaptic function, possibly due to the chronic nature of systemic inflammation in aging and resilience of young animals to acute treatments.

Red Cell Distribution Width Is Directly Associated with Poor Cognitive Performance among Nonanemic, Middle-Aged, Urban Adults

BACKGROUND

Epidemiological evidence suggests that both anemia and elevated red cell distribution width (RDW) are associated with cognitive impairment. However, the interplay between these 2 predictors has been understudied.

OBJECTIVES

We examined sex- and anemia-specific associations between RDW and cognitive performance among urban adults in the United States.

METHODS

Data from the Healthy Aging in Neighborhoods of Diversity Across the Life Span Study (Baltimore, MD; participants aged 30-65 y at baseline, ∼59% African-American, 45% men) were used. Participants were selected based on the completion of 11 cognitive tasks at baseline (2004-2009) and follow-up (2009-2013) visits (mean time between visits: 4.64 ± 0.93 y) and availability of exposure and covariate data, yielding a sample of between 1526 and 1646 adults out of the initial 3720 adults recruited at baseline. Multiple linear mixed-effects regression models were conducted with RDW as the main exposure of interest and anemia/sex as the key effect modifiers.

RESULTS

Overall, high RDWs were linked to poorer baseline performance on the California Verbal Learning Test (CVLT) List A (per 1 unit increase in RDW %, main effect: γ01 = -0.369 ± 0.114; P = 0.001) and to slower rates of decline on the CVLT Delayed Free Recall (per 1 unit increase in RDW %, RDW × time: γ11 = +0.036 ± 0.013; P = 0.007). Among nonanemic participants, RDWs were consistently associated with poorer baseline performance on the Trailmaking Test, Part A (γ01 = +3.11 ± 0.89; P < 0.001) and on the CVLT List A (γ01 = -0.560 ± 0.158; P < 0.001). Moreover, RDWs were associated with poorer baseline performance on the Brief Test of Attention in the total population (γ01 = -0.123 ± 0.039; P = 0.001) and among men (γ01 = -0.221 ± 0.068; P = 0.001). We did not detect an association between hemoglobin (Hb) and baseline cognitive performance or changes over time.

CONCLUSIONS

Elevated RDW had a consistent cross-sectional association with poor cognitive performance in the domains of verbal memory and attention among the nonanemic group in a sample of middle-aged, urban adults. Anemia and Hb concentrations were not associated with cognition. More longitudinal studies are needed to replicate our findings.

Systemic inflammation is associated with depressive symptoms differentially by sex and race: a longitudinal study of urban adults

Systemic inflammation may influence trajectories of depressive symptoms over time, perhaps differentially by sex and race. Inflammatory markers and the Center for Epidemiologic Studies-Depression scale [total score: CES-D_total and four distinctive domains: somatic complaints, depressed affect, positive affect and interpersonal problems] were examined among African-American (AA) and White urban adults participating in the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study [2004-2013, Age_base:30-64 y, mean ± SD follow-up time: 4.64 ± 0.93 y, N = 150 (with cytokine data) to N = 1,767 (with other inflammatory markers)]. Findings suggest that serum concentrations of high-sensitivity C-reactive protein (hsCRP), z-inflammation composite score [ICS, combining elevated hsCRP and ESR with low serum albumin and iron], and serum interleukin (IL) 1β were positively associated with ΔCES-D_total (Δ: annual rate of increase) among Whites only. IL-12 was directly related to ΔCES-D_total among men and AA. The race-specific associations of hsCRP, ICS, IL-1β and the sex-specific association of IL-12 with ΔCES-D_total were replicated for the "depressed affect" domain. Similarly, among men, lower serum albumin and higher ICS were linked with higher baseline "somatic complaints". IL-10 among AA and IL-12 among men were inversely related to Δ"positive affect", while "interpersonal problems" were cross-sectionally associated with IL-6 among AA and IL-10 among Whites. Finally, baseline ICS was positively associated with incident "elevated depressive symptoms" (EDS: CES-D_total ≥ 16) among AA (HR = 1.28, 95% CI: 1.04-1.56, P = 0.017). Overall, systemic inflammation was directly linked to increased depressive symptoms over time and at baseline, differentially across sex and race groups. More longitudinal research is needed to replicate our findings.

Network topology dynamics of circulating biomarkers and cognitive performance in older Cytomegalovirus-seropositive or -seronegative men and women

Background

Cytokines are signaling molecules operating within complex cascade patterns and having exceptional modulatory functions. They impact various physiological processes such as neuroendocrine and metabolic interactions, neurotrophins’ metabolism, neuroplasticity, and may affect behavior and cognition. In our previous study, we found that sex and Cytomegalovirus (CMV)-serostatus may modulate levels of circulating pro- and anti-inflammatory cytokines, metabolic factors, immune cells, and cognitive performance, as well as associations between them.

Results

In the present study, we used a graph-theoretical approach to investigate the network topology dynamics of 22 circulating biomarkers and 11 measures of cognitive performance in 161 older participants recruited to undergo a six-months training intervention. For network construction, we applied coefficient of determination (R²) that was calculated for all possible pairs of variables (N = 33) in four groups (CMV⁻ men and women; CMV⁺ men and women). Network topology has been evaluated by clustering coefficient (CC) and characteristic path length (CPL) as well as local (E_local) and global (E_global) efficiency, showing the degree of network segregation (CC and E_local) and integration (CPL and E_global). We found that networks under consideration showed small-world networks properties with more random characteristics. Mean CC, as well as local and global efficiency were highest and CPL shortest in CMV⁻ males (having lowest inflammatory status and highest cognitive performance). CMV⁻ and CMV⁺ females did not show any significant differences. Modularity analyses showed that the networks exhibit in all cases highly differentiated modular organization (with Q-value ranged between 0.397 and 0.453).

Conclusions

In this work, we found that segregation and integration properties of the network were notably stronger in the group with balanced inflammatory status. We were also able to confirm our previous findings that CMV-infection and sex modulate multiple circulating biomarkers and cognitive performance and that balanced inflammatory and metabolic status in elderly contributes to better cognitive functioning. Thus, network analyses provide a useful strategy for visualization and quantitative description of multiple interactions between various circulating pro- and anti-inflammatory biomarkers, hormones, neurotrophic and metabolic factors, immune cells, and measures of cognitive performance and can be in general applied for analyzing interactions between different physiological systems.

Effect of Systemic Inflammation on Rat Attentional Function and Neuroinflammation: Possible Protective Role for Food Restriction

Background: Aging is characterized by subtle cognitive decline, which correlates with increased peripheral inflammation. Acute activation of the peripheral immune system, via lipopolysaccharide (LPS) injection, elicits deficits in hippocampal-dependent spatial memory. Little is known concerning the effect of chronic inflammation on prefrontal cortex (PFC)-dependent vigilance. We examined the impact of repeated LPS injections in young and middle-age rats on the 5-choice serial reaction time task (5-CSRTT), expecting repeated LPS treatment to induce attentional deficits with greater disruption in middle-age. Methods: Male Fischer-344 rats, 4- and 12-months-old, were food restricted and trained on the 5-CSRTT. Once rats reached criterion, they were injected with LPS (1 mg/kg, i.p.) weekly for 4 weeks and testing started 48 h after each injection. To examine the possibility that mild food restriction inherent to the behavioral task influenced inflammation markers, a second group of food-restricted or ad-lib-fed rats was assessed for cytokine changes 48 h after one injection. Results: Performing LPS-treated rats exhibited a sickness response, manifesting as reduced initiated and completed trials during the first week but recovered by the second week of testing. After the first week, LPS-treated rats continued to exhibit longer response latencies, despite no change in food retrieval latency, suggestive of LPS-induced cognitive slowing. Similarly, LPS-induced impairment of attention was observed as increased omissions with heightened cognitive demand and increased age. Repeated LPS-treatment increased the level of PFC IL-1α, and PFC IL-6 was marginally higher in middle-age rats. No effect of age or treatment was observed for plasma cytokines in performing rats. Histological examination of microglia indicated increased colocalization of Iba1+ and CD68+ cells from middle-age relative to young rats. Examination of food restriction demonstrated an attenuation of age- and LPS-related increases in plasma cytokine levels. Conclusions: Systemic inflammation, induced through LPS treatment, impaired attentional function, which was independent of sickness and exacerbated by increased cognitive demand and increased age. Additional studies revealed that food restriction, associated with the task, attenuated markers of neuroinflammation and plasma cytokines. The results emphasize the need for improved methods for modeling low-level chronic systemic inflammation to effectively examine its impact on attention during aging.

The Interplay of Diet Quality and Alzheimer's Disease Genetic Risk Score in Relation to Cognitive Performance Among Urban African Americans

We examined the interactive associations of poor diet quality and Alzheimer’s Disease (AD) genetic risk with cognitive performance among 304 African American adults (mean age~57 years) from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study. In this cross-sectional study, selected participants had complete predictors and covariate data with 13 cognitive test scores as outcomes. Healthy Eating Index-2010 (HEI-2010), Dietary Approaches to Stop Hypertension (DASH), and mean adequacy ratio (MAR) were measured. A genetic risk score for AD in HANDLS (hAlzScore) was computed from 12 selected single nucleotide polymorphisms (SNPs). Our key hypotheses were tested using linear regression models. The hAlzScore was directly associated with poor performance in verbal memory (−0.4 ± 0.2, 0.01) and immediate visual memory (0.4 ± 0.2, 0.03) measured in seconds, in women only. The hAlzScore interacted synergistically with poorer diet quality to determine lower cognitive performance on a test of verbal fluency. Among numerous SNP × diet quality interactions for models of cognitive performance as outcomes, only one passed correction for multiple testing, namely verbal fluency. Our results suggest that improved diet quality can potentially modify performance on cognitive tests of verbal fluency among individuals with higher AD genetic risk.

Cytokines are associated with longitudinal changes in cognitive performance among urban adults

BACKGROUND

Chronic systemic inflammation has been positively associated with structural and functional brain changes representing early markers of Alzheimer's Disease (AD) and cognitive decline. The current study examined associations between systemic inflammation and cognitive performance among African-Americans and Whites urban adults.

METHODS

Participants were selected from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study (2004-2013, baseline age: 30-64 y, mean ± SD follow-up time of 4.64 ± 0.93 y, N = 189-222, k = 1.5-1.7 observations/participant). Cytokines known to be positively linked to AD incidence among others were tested against cross-sectional and longitudinal cognitive function, stratifying by age group (≤50 y vs. >50 y), sex and race. A series of mixed-effects regression models were conducted, adjusting for key confounders.

RESULTS

Among key findings, IL1β was positively associated with a faster rate of decline on a test of executive functioning, among older adults (age >50 y, γ₁₁ = +2.49 ± 0.89, p = 0.005), while in the total population, IL-6 was linked to a faster decline on a test of verbal memory (γ₁₁ = -0.011 ± 0.004, p = 0.009). Among younger participants, IL-18 was linked to a poorer performance on a test of attention at baseline (age ≤50 y, γ₀₁ = -0.007 ± 0.0025, p = 0.004) though a slower rate of decline with higher IL-18 was detected for a test of psychomotor speed in older adults (age >50 y, γ₁₁ = +0.0010 ± 0.0004, p = 0.008). Finally, among Whites, unlike among African-Americans, IL-6 was associated with a better baseline performance on two tests of verbal and working memory.

CONCLUSIONS

Cytokines were shown to be associated with age-related cognitive decline among middle-aged and older urban adults in an age group and race-specific manner. Further longitudinal studies are needed to replicate our findings and mediation through relevant biological and psychosocial factors need to be studied as well.