The association between systemic inflammation and cognitive performance in the elderly: the Sydney Memory and Ageing Study

The Immunomodulatory Effects of Plant Extracts and Plant Secondary Metabolites on Chronic Neuroinflammation and Cognitive Aging: A Mechanistic and Empirical Review

Advances in healthcare have considerably improved the life expectancy of the human population over the last century and this has brought about new challenges. As we live longer the capacity for cognitive aging increases. Consequently, it has been noted that decline in cognitive performance in the elderly in domains of reasoning, problem solving skills, attention, processing speed, working memory and episodic memory is a significant societal problem. Despite the enormity of this issue there are relatively few interventions for cognitive aging. This may be due to our current state of knowledge on biological factors that underpin cognitive aging. One of the biological contributors to cognitive aging is chronic neuroinflammation. This review will provide an overview of the peripheral and central mechanisms involved in chronic neuroinflammation and how neuroinflammation may be related to age-associated cognitive decline. Plant based extracts including herbal and nutritional supplements with anti-inflammatory properties will be examined in relation to their utility in treating age-related cognitive decline. Plant based extracts in particular offer interesting pharmacological properties that may be quickly utilized to prevent cognitive aging.

Structural brain changes and all-cause mortality in the elderly population-the mediating role of inflammation

While MRI brain changes have been related to mortality during ageing, the role of inflammation in this relationship remains poorly understood. Hence, this study aimed to investigate the impact of MRI changes on all-cause mortality and the mediating role of cytokines. All-cause mortality was evaluated in 268 community dwelling elderly (age 65-83 years) in the MEMO study (Memory and Morbidity in Augsburg elderly). MRI markers of brain atrophy and cerebral small vessel disease (SVD), C-reactive protein (CRP) and a panel of cytokines in serum were assessed. Cox proportional hazard models were used to estimate the association of MRI changes with survival over 9 years. Regression models were used to assess the hypothesis that inflammation is mediating the relationship between MRI-brain changes and mortality. In total, 77 (29 %) deaths occurred during a mean follow up of 9 years. After adjusting for confounders, the degree of global cortical atrophy and the level of the cytokines CRP, TNF-α and IL-8 were of higher significance in study participants who had died at follow-up in comparison to survivors. In Cox proportional hazard models, higher degrees of global cortical atrophy (HR 1.56, p = 0.003) and regional atrophy of the temporal lobe (HR 1.38, p = 0.011) were associated with a significantly increased risk of mortality. Mediation analyses revealed a partial mediation by IL-6 and IL-8 of the effects of global cortical atrophy on mortality. Global cortical brain atrophy is a significant indicator of survival in the elderly. Our study supports a possible role for inflammation in the atrophy pathogenesis. If replicated in other samples, IL-6 and IL-8 level assessment may improve risk prognosis for mortality.

Attenuation of stress induced memory deficits by nonsteroidal anti-inflammatory drugs (NSAIDs) in rats: Role of antioxidant enzymes

BACKGROUND

Repeated stress paradigms have been shown to cause devastating alterations on memory functions. Stress is linked with inflammation. Psychological and certain physical stressors could lead to neuroinflammation. Inflammatory process may occur by release of mediators and stimulate the production of prostaglandins through cyclooxygenase (COX). Treatment with COX inhibitors, which restrain prostaglandin production, has enhanced memory in a number of neuroinflammatory states showing a potential function for raised prostaglandins in these memory shortfalls. In the present study, potential therapeutic effects of indomethacin and diclofenac sodium on memory in both unrestraint and restraint rats were observed.

METHODS AND RESULTS

Two components, long term memory and short term memory were examined by Morris water maze (MWM) and elevated plus maze (EPM) respectively. The present study also demonstrated the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on lipid peroxidation (LPO) and activities of antioxidant enzymes along with the activity of acetylcholinesterase (AChE). Results of MWM and EPM showed significant effects of drugs in both unrestraint and restraint rats as escape latency and transfer latency, in respective behavioral models were decreased as compared to that of control. This study also showed NSAIDs administration decreased LPO and increased antioxidant enzymes activity and decreased AChE activity in rats exposed to repeated stress.

CONCLUSION

In conclusion this study suggests a therapeutic potential of indomethacin and diclofenac against repeated stress-induced memory deficits.

A Bidirectional Relationship between Executive Function and Health Behavior: Evidence, Implications, and Future Directions

Physically active lifestyles and other health-enhancing behaviors play an important role in preserving executive function into old age. Conversely, emerging research suggests that executive functions facilitate participation in a broad range of healthy behaviors including physical activity and reduced fatty food, tobacco, and alcohol consumption. They do this by supporting the volition, planning, performance monitoring, and inhibition necessary to enact intentions and override urges to engage in health damaging behavior. Here, we focus firstly on evidence suggesting that health-enhancing behaviors can induce improvements in executive function. We then switch our focus to findings linking executive function to the consistent performance of health-promoting behaviors and the avoidance of health risk behaviors. We suggest that executive function, health behavior, and disease processes are interdependent. In particular, we argue that a positive feedback loop may exist whereby health behavior-induced changes in executive function foster subsequent health-enhancing behaviors, which in turn help sustain efficient executive functions and good health. We conclude by outlining the implications of this reciprocal relationship for intervention strategies, the design of research studies, and the study of healthy aging.

Relation between aerobic fitness and brain structures in amnestic mild cognitive impairment elderly

Mild cognitive impairment (aMCI) is a clinical condition, with high risk to develop Alzheimer's disease. Physical exercise may have positive effect on cognition and brain structure in older adults. However, it is still under research whether these influences are true on aMCI subjects with low Ab_42 and high total tau in cerebrospinal fluid (CSF), which is considered a biomarker for AD. Therefore, we aimed to investigate a possible relation between aerobic fitness (AF) and gray matter (GM) volume and AF and white matter (WM) integrity in aMCI with a CSF biomarker. Twenty-two participants with aMCI acquired the images on a 3.0-T MRI. AF was assessed by a graded exercise test on a treadmill. Voxel-based morphometry and tract-based spatial statistic methods were used to analyze the GM volume and WM microstructural integrity, respectively. We correlated AF and GM volume and WM integrity in aMCI (p < 0.05, FWE corrected, cluster with at least five voxels). There was a positive relation between AF and GM volume mostly in frontal superior cortex. In WM integrity, AF was positively correlated with fractional anisotropy and negatively correlated with mean diffusivity and radial diffusivity, all in the same tracts that interconnect frontal, temporal, parietal, and occipital areas (longitudinal fasciculus, fronto-occipital fasciculus, and corpus callosum). These results suggest that aerobic fitness may have a positive influence on protection of brain even in aMCI CSF biomarker, a high-risk population to convert to AD.

Wide range of body composition measures are associated with cognitive function in community-dwelling older adults

AIM

Studies of the association between body composition, both body fat and body muscle, and cognitive function are rarely reported. The aim of the present study was to determine the association between a wide range of body composition measures with cognitive function in older adults.

METHODS

A total of 2322 Malaysian older adults aged 60 years and older were recruited using multistage random sampling in a population-based cross-sectional study. Out of 2322 older adults recruited, 2309 (48% men) completed assessments on cognitive function and body composition. Cognitive functions were assessed using the Malay version of the Mini-Mental State Examination, the Bahasa Malaysia version of Montreal Cognitive Assessment, Digit Span Test, Digit Symbol Test and Rey Auditory Verbal Learning Test. Body composition included body mass index, mid-upper arm circumference, waist circumference, calf circumference, waist-to-hip ratio, percentage body fat and skeletal muscle mass.

RESULTS

The association between body composition and cognitive functions was analyzed using multiple linear regression. After adjustment for age, education years, hypertension, hypercholesterolemia, diabetes mellitus, depression, smoking status and alcohol consumption, we found that calf circumference appeared as a significant predictor for all cognitive tests among both men and women (P < 0.05), except for the Rey Auditory Verbal Learning Test. Waist-to-hip ratio was detected as a significant predictor for all cognitive tests among women (P < 0.05), but was only a significant predictor for the Bahasa Malaysia version of Montreal Cognitive Assessment among men (P < 0.05).

CONCLUSIONS

These results suggest that there is a need to maintain muscle mass and lower adipose tissue among older adults for optimal cognitive function. Geriatr Gerontol Int 2017; 17: 554-560.

Lifestyle Shapes the Dialogue between Environment, Microglia, and Adult Neurogenesis

Lifestyle modulates brain function. Diet, stress levels, and physical exercise among other factors influence the "brain cognitive reserve", that is, the capacity of the brain to maintain a normal function when confronting neurodegenerative diseases, injury, and/or aging. This cognitive reserve relays on several cellular and molecular elements that contribute to brain plasticity allowing adaptive responses to cognitive demands, and one of its key components is the hippocampal neurogenic reserve. Hippocampal neural stem cells give rise to new neurons that integrate into the local circuitry and contribute to hippocampal functions such as memory and learning. Importantly, adult hippocampal neurogenesis is well-known to be modulated by the demands of the environment and lifestyle factors. Diet, stress, and physical exercise directly act on neural stem cells and/or their progeny, but, in addition, they may also indirectly affect neurogenesis by acting on microglia. Microglia, the guardians of the brain, rapidly sense changes in the brain milieu, and it has been recently shown that their function is affected by lifestyle factors. However, few studies have analyzed the modulatory effect of microglia on adult neurogenesis in these conditions. Here, we review the current knowledge about the dialogue maintained between microglia and the hippocampal neurogenic cascade. Understanding how the communication between microglia and hippocampal neurogenesis is affected by lifestyle choices is crucial to maintain the brain cognitive reserve and prevent the maladaptive responses that emerge during disease or injury through adulthood and aging.

Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows' milk

Background

Cows’ milk generally contains two types of β-casein, A1 and A2 types. Digestion of A1 type can yield the peptide β-casomorphin-7, which is implicated in adverse gastrointestinal effects of milk consumption, some of which resemble those in lactose intolerance. This study aimed to compare the effects of milk containing A1 β-casein with those of milk containing only A2 β-casein on inflammation, symptoms of post-dairy digestive discomfort (PD3), and cognitive processing in subjects with self-reported lactose intolerance.

Methods

Forty-five Han Chinese subjects participated in this double-blind, randomized, 2 × 2 crossover trial and consumed milk containing both β-casein types or milk containing only A2 β-casein. Each treatment period was 14 days with a 14-day washout period at baseline and between treatment periods. Outcomes included PD3, gastrointestinal function (measured by smart pill), Subtle Cognitive Impairment Test (SCIT), serum/fecal laboratory biomarkers, and adverse events.

Results

Compared with milk containing only A2 β-casein, the consumption of milk containing both β-casein types was associated with significantly greater PD3 symptoms; higher concentrations of inflammation-related biomarkers and β-casomorphin-7; longer gastrointestinal transit times and lower levels of short-chain fatty acids; and increased response time and error rate on the SCIT. Consumption of milk containing both β-casein types was associated with worsening of PD3 symptoms relative to baseline in lactose tolerant and lactose intolerant subjects. Consumption of milk containing only A2 β-casein did not aggravate PD3 symptoms relative to baseline (i.e., after washout of dairy products) in lactose tolerant and intolerant subjects.

Conclusions

Consumption of milk containing A1 β-casein was associated with increased gastrointestinal inflammation, worsening of PD3 symptoms, delayed transit, and decreased cognitive processing speed and accuracy. Because elimination of A1 β-casein attenuated these effects, some symptoms of lactose intolerance may stem from inflammation it triggers, and can be avoided by consuming milk containing only the A2 type of beta casein.

Trial registration

ClinicalTrials.gov/NCT02406469

Electronic supplementary material

The online version of this article (doi:10.1186/s12937-016-0147-z) contains supplementary material, which is available to authorized users.

Protective effects of resveratrol on aging-induced cognitive impairment in rats

Resveratrol, a polyphenol phytoalexine, has been shown to play a neuroprotective role in the neurodegenerative process in Alzheimer's disease (AD) and improve memory function in dementia. However, the in vivo effect of resveratrol in normal aging models of learning and memory has not yet been evaluated. Therefore, the present neurobehavioral study was undertaken to evaluate the effect of resveratrol on cognitive impairment induced by aging in passive avoidance and Morris water maze (MWM) tests. Male Wistar albino rats were divided into four groups: young control (4month), young resveratrol (4month+RESV), old control (24month) and old resveratrol (24month+RESV). Resveratrol (50mg/kg/day) was given to the 4month+RESV and 24month+RESV groups orally for 12weeks. There was no significant difference between the groups for the first day of latency, while in aged rats, the second day of latency was significantly shortened compared to the young group in the passive avoidance test (p<0.05). Additionally, in the MWM test, the results showed a decrease in the time spent in the escape platform's quadrant in the probe test in aged rats (p<0.05). The administration of resveratrol at 50mg/kg/day increased the retention scores in the passive avoidance test and the time spent in the escape platform's quadrant in the MWM task (p<0.05). Furthermore resveratrol attenuated the protein levels of TNFα and IL1β in the 24-month group. These findings indicate that aging impairs emotional and spatial learning-memory and resveratrol reverses the effect of age-related learning and memory impairment. The results of this study suggest that resveratrol is effective in preventing cognitive deficit in aged rats by inhibiting the production of inflammatory cytokines.

Complex mechanisms linking neurocognitive dysfunction to insulin resistance and other metabolic dysfunction

Scientific evidence has established several links between metabolic and neurocognitive dysfunction, and epidemiologic evidence has revealed an increased risk of Alzheimer’s disease and vascular dementia in patients with diabetes. In July 2015, the National Institute of Diabetes, Digestive, and Kidney Diseases gathered experts from multiple clinical and scientific disciplines, in a workshop entitled “The Intersection of Metabolic and Neurocognitive Dysfunction”, to clarify the state-of-the-science on the mechanisms linking metabolic dysfunction, and insulin resistance and diabetes in particular, to neurocognitive impairment and dementia. This perspective is intended to serve as a summary of the opinions expressed at this meeting, which focused on identifying gaps and opportunities to advance research in this emerging area with important public health relevance.

Flow-Mediated Dilation and Neurocognition: Systematic Review and Future Directions

BACKGROUND

Previous literature indicates that flow-mediated dilation (FMD) is associated with impaired cognition among patients with stroke. The relationship between FMD and cognition in individuals without cerebrovascular disease has yet to be systematically reviewed.

METHODS

The literature was searched using MEDLINE. Exclusion criteria were as follows: focus on neurological disease (e.g., stroke), animal studies, no quantitative measure of endothelial function or cognition, newborn studies, articles with no original data, and articles that are irrelevant to the topic of interest. Neurocognitive tests were categorized in the following domains: executive function, memory (general, working, episodic/semantic, verbal, visual), global cognitive function, information processing speed, language, psychomotor speed, and visual-spatial ability.

RESULTS

The search yielded 700 articles, of which 10 articles, consisting of 2791 participants, met the criteria for inclusion. Most studies conclude that impaired FMD is associated with poorer neuropsychological functioning, particularly in executive functioning (effect sizes: r = 0.07-0.58) and working memory tasks (effect sizes: r = 0.19-0.39). No association was found between other subdomains of memory and FMD. Visual spatial tasks, information processing speed, language tasks, and global cognition were not associated with FMD overall; however fewer studies examined these domains.

CONCLUSIONS

Even in the absence of cerebrovascular disease, there are links between cognition, particularly executive tasks, and vascular function. Public health implications include the potential value of examining FMD as a predictor of cognitive decline, as well as the potential value of improving cognition through pharmacological and behavioral interventions that improve vascular function. Future studies incorporating neuroimaging measures of cerebral blood flow are warranted.

Obesity and sex interact in the regulation of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, for which a number of genetic, environmental, and lifestyle risk factors have been identified. A significant modifiable risk factor is obesity in mid-life. Interestingly, both obesity and AD exhibit sex differences and are regulated by sex steroid hormones. Accumulating evidence suggests interactions between obesity and sex in regulation of AD risk, although the pathways underlying this relationship are unclear. Inflammation and the E4 allele of apolipoprotein E have been identified as independent risk factors for AD and both interact with obesity and sex steroid hormones. We review the individual and cooperative effects of obesity and sex on development of AD and examine the potential contributions of apolipoprotein E, inflammation, and their interactions to this relationship.

An inverse relationship between serum macrophage inhibitory cytokine-1 levels and brain white matter integrity in community-dwelling older individuals

Macrophage inhibitory cytokine-1 (MIC-1/GDF15) is a marker of inflammation that has been associated with atherosclerosis. We have previously demonstrated its relationships with cognitive decline and cerebral gray matter volumes, suggesting its role as a biomarker of cognitive impairment. Considering that it is widely distributed in the brain, and both inflammation and vascular pathology impact on white matter (WM) integrity, we examined the relationship between MIC-1/GDF15 and measures of WM integrity, including WM volumes, mean fractional anisotropy (FA) values and WM hyperintensity (WMH) volumes in a community-dwelling non-demented sample of older individuals (n=327, 70-90 years old). We found that the mean FA values were negatively associated with MIC-1/GDF15 serum levels, after Bonferroni correction. The voxel-wise analysis showed negative relationships between MIC-1/GDF15 serum levels and FA values in corticospinal tract, corpus callosum (including genu, body and splenium parts), superior longitudinal fasciculus, cingulum, as well as anterior and posterior thalamic radiation. Whole brain WMH volumes, especially deep WMH volumes, showed a non-significant trend for a positive association with MIC-1/GDF15 serum levels. The associations between MIC-1/GDF15 serum levels and WM integrity showed a non-significant trend of being stronger for the individuals classified as mild cognitive impairment, compared to the normal ageing participants. The findings suggest that high serum MIC-1/GDF15 levels indicate reduced WM integrity and possibly greater WM pathology.

Stress Regulation as a Link between Executive Function and Pre-Frailty in Older Adults

OBJECTIVES

Both pre-frailty and frailty are linked with impaired executive function (EF) but the mechanism underlying this relationship is not known. Williams and colleagues' model posits EF affects health outcomes via stress regulation. This model was utlized to test indicators of stress regulation as mediators of the relationship between EF and pre-frailty in older adults.

DESIGN

Cross-sectional.

SETTING

Academic general clinical research centers.

PARTICIPANTS

690 community-dwelling older adults ≥ 50 years of age.

MEASUREMENTS

Pre-frailty was measured using a modified form of the Fried Frailty measure. EF was assessed via telephone-based neurocognitive assessments. Indicators of stress regulation included: stress exposure (measured by perceived stress), reactivity and recovery (measured by heart rate) and restoration (measured by serum interleukin-6 and sleep quality).

RESULTS

396 individuals were classified as non-frail, 277 as pre-frail, and 17 as frail. Pre-frail and non-frail individuals were included in data analyses. Compared to non-frail individuals, pre-frail were older and exhibited poorer EF, higher levels of stress exposure and poorer stress restoration. Poorer EF was associated with greater stress exposure, less stress reactivity, longer stress recovery and poorer stress restoration. The total effect of the relationship between EF and pre-frailty was significant with significant indirect effects supporting stress exposure and restoration as mediators of the relationship.

CONCLUSION

Stress exposure and restoration appear to mediate the relationship between EF and pre-frailty. Longitudinal studies are needed to clarify the direction of causality and determine whether stress regulation processes are appropriate targets for interventions aiming to prevent declines in EF and the development of pre-frailty.

Inflammatory Markers Change with Age, but do not Fall Beyond Reported Normal Ranges

We examined the serum levels of IL-6, IL-8, TNF, IL-6R, TNF-R1, and CRP and the dynamics of changes in these levels according to age. The study included healthy individuals of 20–90 years of age. Participants were divided into subgroups based on their decade of life, and into subgroups of ≥65 or <65 years. Serum cytokine levels were assayed by ELISA, and CRP using an immunoturbidimetric method. Serum CRP levels were within the normal range for all subgroups. The 60- to 70-year age group showed higher CRP than the 20- to 30- (p = 0.003), 30- to 40- (p = 0.009), and 40- to 50- (p = 0.030) year age groups. Serum cytokine levels were low. It was greater in the 60- to 70-year age group than in the 20- to 30- (p = 0.008) and 30- to 40- (p = 0.040) year groups, and was greater in the 70- to 90-year group than the 20- to 30-year group (p = 0.043). Serum TNF-R1 level in the 70- to 90-year group was greater than in all other age groups (p = 0.000 for all comparisons). Other measured parameters did not differ between groups. Serum levels of IL-6, CRP, and TNF-R1 were greater in participants ≥65 than <65 years of age. Healthy older people showed low serum levels of CRP and pro-inflammatory cytokines, but higher than in younger population. Therefore, the adjustment of normal ranges in the elderly should be considered. Serum levels of pro-inflammatory cytokines elevated beyond normal ranges indicate particular diseases.

Cytokines and Postoperative Delirium in Older Patients Undergoing Major Elective Surgery

BACKGROUND

A proinflammatory state has been associated with several age-associated conditions; however, the inflammatory mechanisms of delirium remain poorly characterized.

METHODS

Using the Successful Aging after Elective Surgery Study of adults age ≥70 undergoing major noncardiac surgery, 12 cytokines were measured at four timepoints: preoperative, postanesthesia care unit, postoperative day 2 (POD2) and 30 days later (POD1M). We conducted a nested, longitudinal matched (on age, sex, surgery type, baseline cognition, vascular comorbidity, and Apolipoprotein E genotype) case-control study: delirium cases and no-delirium controls were selected from the overall cohort (N = 566; 24% delirium). Analyses were independently conducted in discovery, replication, and pooled cohorts (39, 36, 75 matched pairs, respectively). Nonparametric signed-rank tests evaluating differences in cytokine levels between matched pairs were used to identify delirium-associated cytokines.

RESULTS

In the discovery and replication cohorts, matching variables were similar in cases and controls. Compared to controls, cases had (*p < .05, **p < .01) significantly higher interleukin-6 on POD2 in the discovery, replication, and pooled cohorts (median difference [pg/mL] 50.44**, 20.17*, 39.35**, respectively). In the pooled cohort, cases were higher than controls for interleukin-2 (0.99*, 0.77*, 1.07**, 0.73* at preoperative, postanesthesia care unit, POD2, POD1M, respectively), vascular endothelial growth factor (4.10* at POD2), and tumor necrosis factor-alpha (3.10* at POD1M), while cases had lower interleukin-12 at POD1M (-4.24*).

CONCLUSIONS

In this large, well-characterized cohort assessed at multiple timepoints, we observed an inflammatory signature of delirium involving elevated interleukin-6 at POD2, which may be an important disease marker for delirium. We also observed preliminary evidence for involvement of other cytokines.

Heat stress-induced memory impairment is associated with neuroinflammation in mice

BACKGROUND

Heat stress induces many pathophysiological responses and has a profound impact on brain structure. It has been demonstrated that exposure to high temperature induces cognitive impairment in experimental animals and humans. Although the effects of heat stress have long been studied, the mechanisms by which heat stress affects brain structure and cognition not well understood.

METHODS

In our longitudinal study of mice exposed to heat over 7, 14, or 42 days, we found that heat stress time dependently impaired cognitive function as determined by Y-maze, passive avoidance, and novel object recognition tests. To elucidate the histological mechanism by which thermal stress inhibited cognitive abilities, we examined heat stress-induced inflammation in the hippocampus.

RESULTS

In mice subjected to heat exposure, we found: 1) an increased number of glial fibrillary acid protein (GFAP)- and macrophage-1 antigen (Mac-1)-positive cells, 2) up-regulated nuclear factor (NF)-κB, a master regulator of inflammation, and 3) marked increases in cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and cytokine interleukin (IL)-1β and tumor necrosis factor (TNF)-α in the mouse hippocampus. We also observed that neuronal and synaptic densities were degenerated significantly in hippocampal regions after heat exposure, as determined by histological analysis of neuronal nuclei (NeuN), postsynaptic density protein 95 (PSD-95), and synaptophysin expression. Moreover, in heat-exposed mice, we found that the number of cells positive for doublecortin (DCX), a marker of neurogenesis, was significantly decreased compared with control mice. Finally, anti-inflammatory agent minocycline inhibited the heat stress-induced cognitive deficits and astogliosis in mice.

CONCLUSIONS

Together, these findings suggest that heat stress can lead to activation of glial cells and induction of inflammatory molecules in the hippocampus, which may act as causative factors for memory loss, neuronal death, and impaired adult neurogenesis.

Asthma control and cognitive function in a cohort of elderly adults

OBJECTIVES

To determine whether poor asthma control is associated with cognitive impairment in a cohort of older, inner-city adults with asthma.

DESIGN

Prospective observational cohort study.

SETTING

Outpatient practices in New York City and Chicago.

PARTICIPANTS

Individuals aged 60 and older with a physician diagnosis of asthma and without chronic obstructive pulmonary disease or a smoking history of 10 pack-years or more (N = 452).

MEASUREMENTS

Cognitive assessments that included processing speed (pattern comparison, Trail-Making Test Part A), executive function (Trail-Making Test Part B), attention and working memory (letter number sequencing), immediate and delayed recall (Wechsler Memory Scale Story A), word fluency (animal naming), and global cognitive function (Mini-Mental State Examination) were administered. Asthma control was measured using the Asthma Control Questionnaire (ACQ) and airway obstruction using spirometry as the predicted forced expiratory volume at 1 second (FEV1) of less than 70%. Cognitive measures were modeled in linear and logistic regression models controlling for age, race, education, English proficiency, and income.

RESULTS

Participants had a mean age of 68; 41% had poor asthma control according to the ACQ, and 35% had FEV1 of less than 70%. Poor asthma control and FEV1 less than 70% were significantly associated with all measures of cognitive function in univariate analyses, although these associations lost their statistical significance after adjusting for age, education, English proficiency, and other covariates. The same pattern was observed when the outcomes were below-normal performance on the cognitive measures based on normative data.

CONCLUSION

Poor asthma control and airway obstruction are not associated with poor performance on various measures of cognitive function in older adults with asthma.

Adiposity estimated using dual energy X-ray absorptiometry and body mass index and its association with cognition in elderly adults

OBJECTIVES

To determine whether obesity, estimated according to body mass index (BMI), waist circumference, and body fat and abdominal fat assessed using dual-energy X-ray absorptiometry (DEXA), was associated with cognitive performance.

DESIGN

Cross-sectional.

SETTING

Community based.

PARTICIPANTS

Individuals aged 74-94 (N = 406).

MEASUREMENTS

BMI, waist circumference, body fat, and abdominal fat were assessed using DEXA. Cognitive performance was assessed using a comprehensive neuropsychological battery.

RESULTS

When categorized using BMI, overweight individuals had higher global cognitive function and executive function scores than normal-weight individuals. This relationship did not differ according to sex. When categorized according to DEXA, there were no relationships between body fat and cognitive function in the whole group, but women in the middle and highest tertiles of DEXA body fat had better executive function than those in the lowest tertile. Men in the middle tertile of DEXA body fat had significantly better executive function and memory than those in the lowest tertile. BMI had greater power to predict executive function than DEXA body fat. No significant associations were found between cognition and estimates of abdominal adiposity.

CONCLUSION

This study found an association between being overweight and better executive function in elderly adults; this association was stronger for the simpler BMI than the more-elaborate DEXA measures.

The Association Between Reduced Inflammation and Cognitive Gains After Bariatric Surgery

OBJECTIVE

Bariatric surgery is associated with improved cognitive function, although the mechanisms are unclear. Elevated inflammation is common in obesity and associated with impaired cognition. Inflammation decreases after bariatric surgery, implicating it as a possible mechanism for cognitive improvement. The objective of this study was to examine whether reduced inflammation is a possible mechanism for postoperative cognitive improvement in bariatric surgery patients.

METHODS

Participants were 77 bariatric surgery patients who completed cognitive testing before surgery and 1 year postsurgery. Cognitive domains assessed were attention/executive function, language, and memory. High-sensitivity C-reactive protein (CRP) was assessed at both time points.

RESULTS

Patients exhibited preoperative cognitive impairment, although improvements 1 year postsurgery were seen in both attention/executive function (mean [M; standard deviation {SD}]baseline = 53.57 [8.68] versus M (SD)follow-up= 60.32 [8.19]) and memory (M [SD]baseline= 44.96 [7.98] versus M [SD]follow-up= 51.55 [8.25]). CRP was elevated at baseline and fell into the normative range postsurgery (M [SD]baseline= 0.9 [0.7] versus M [SD]follow-up= 0.2 [0.3] mg/dl). Preoperative CRP was not associated with baseline cognitive function (β values = -0.10 to 0.02) and changes in CRP also did not correspond to changes in cognition postsurgery (β values = 0.02-0.11; p values > .05 for all domains). A trend was detected for smaller improvements in memory among participants with elevated baseline CRP (>0.30 mg/dl) versus those with normal levels (group × time: p = .083).

CONCLUSIONS

Improvements in high-sensitivity CRP were not associated with postoperative cognitive benefits. Future studies are needed to explore other inflammatory markers and potential mechanisms of cognitive improvement after bariatric surgery, including improved glycemic control and neurohormone changes.

Premature immunosenescence is associated with memory dysfunction in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) has been associated with premature immunosenescence and an increased prevalence of age-related morbidities including poor cognitive function.

OBJECTIVE

We explored the relationships among lymphocyte subsets and memory in RA.

METHODS

Thirty patients with RA and 19 age-matched healthy controls took part in this study. Cognitive function stress and depression scores were evaluated by structured clinical questionnaires. Lymphocytes were isolated and immunophenotyped by flow cytometry to investigate the following subsets: B cells, activated and naïve/memory T cells, regulatory FoxP3+ T (Treg) cells, Th17+ cells, NK cells and senescence-associated CD28- T cells.

RESULTS

RA patients were more depressed than controls, but stress levels were similar in the 2 groups. Patients had impaired memory performance compared to controls, demonstrated by lower Mini-Mental State Examination scores and logical and working memories (all p < 0.0001). These group effects remained significant after correcting for depression and age. Patients had expansion of regulatory T cells, naïve CD4+ T cells and CD8+CD28- cells but reduced percentages of B cells and memory CD8+CD45RO+ T cells compared to controls. CD8+CD28- and CD8+CD45RO+ T cells were found to be negatively associated with memory.

CONCLUSION

RA patients had reduced memory performance compared to healthy controls. Expansion of activated and senescence-associated T cells was correlated with poor memory performance.

Obesity and cognitive decline: role of inflammation and vascular changes

The incidence of obesity in middle age is increasing markedly, and in parallel the prevalence of metabolic disorders including cardiovascular disease and type II diabetes is also rising. Numerous studies have demonstrated that both obesity and metabolic disorders are associated with poorer cognitive performance, cognitive decline, and dementia. In this review we discuss the effects of obesity on cognitive performance, including both clinical and preclinical observations, and discuss some of the potential mechanisms involved, namely inflammation and vascular and metabolic alterations.

Induced mild systemic inflammation is associated with impaired ability to improve cognitive task performance by practice

Elevated inflammatory levels are linked to poorer cognition, but experimental confirmation is lacking. This report examined associations between cognitive performance and inflammation induced by exercise and vaccination. Thirty-six (exercise N = 18, vaccination N = 18) healthy males completed a paced auditory serial addition test (PASAT), which is a multifaceted measure of cognitive function. The task was completed in placebo and elevated inflammation states. Improvements in PASAT performance were related to inflammation. In the exercise study, IL-6 during the first PASAT negatively correlated with PASAT improvement (p = .022). In the vaccination study, increases in C-reactive protein between PASATs correlated with reduced PASAT improvement (p < .001). Inflammation was linked to reduced improvements in cognitive performance. Further research should identify the specific cognitive functions affects and the underlying mechanisms.

Obesity and neuroinflammation: a pathway to cognitive impairment

Obesity is a growing problem worldwide and is associated with a range of comorbidities, including cognitive dysfunction. In this review we will address the evidence that obesity and high fat feeding can lead to cognitive dysfunction. We will also examine the idea that obesity-associated systemic inflammation leads to inflammation within the brain, particularly the hypothalamus, and that this is partially responsible for these negative cognitive outcomes. Thus, obesity, and high fat feeding, lead to systemic inflammation and excess circulating free fatty acids. Circulating cytokines, free fatty acids and immune cells reach the brain at the level of the hypothalamus and initiate local inflammation, including microglial proliferation. This local inflammation likely causes synaptic remodeling and neurodegeneration within the hypothalamus, altering internal hypothalamic circuitry and hypothalamic outputs to other brain regions. The result is disruption to cognitive function mediated by regions such as hippocampus, amygdala, and reward-processing centers. Central inflammation is also likely to affect these regions directly. Thus, central inflammation in obesity leads not just to disruption of hypothalamic satiety signals and perpetuation of overeating, but also to negative outcomes on cognition.

Sex-specific associations between Neutrophil Gelatinase-Associated Lipocalin (NGAL) and cognitive domains in late-life depression

BACKGROUND

Although it is well established that late-life depression is associated with both systemic low-graded inflammation and cognitive impairment, the relation between inflammation and cognition in depressed older persons is still equivocal. The objective of this study is to examine the association between plasma Neutrophil Gelatinase-Associated Lipocalin (NGAL) concentrations and cognitive functioning in late-life depression, including the potentially moderating role of sex.

METHODS

A total of 369 depressed older persons (≥60 years) from The Netherlands study of Depression in Older persons (NESDO) were included. Four cognitive domains, i.e. verbal memory, processing speed, interference control and attention were assessed with three cognitive tests (Stroop test, Wais Digit span test, and Rey's verbal learning test). Multiple linear regression analyses were applied with the four cognitive domains as dependent variables adjusted for confounders.

RESULTS

The association between NGAL levels and specific cognitive domains were sex-specific. In women, higher NGAL levels were associated with impaired verbal memory and lower processing speed. In men, higher NGAL levels were associated with worse interference control. Higher NGAL levels were not associated with attention. No sex-specific associations of either high sensitivity C-reactive protein (hsCRP) or interleukin-6 (IL-6) with cognitive functioning were found.

CONCLUSION

This study shows sex-specific association of NGAL with cognitive functioning in late-life depression.

Pre-operative history of depression and cognitive changes in bariatric surgery patients

Obesity-associated cognitive impairments may be partially reversible through bariatric surgery. Depression, a prevalent comorbidity in bariatric surgery candidates, is linked with cognitive impairment and poorer surgical outcomes in other populations. No study has examined the effects of pre-operative depression on cognitive changes in bariatric surgery patients. Sixty-seven bariatric surgery patients completed a computerized cognitive test battery prior to surgery and 12 months post-operatively. The structured clinical interview for the DSM-IV Axis I disorders assessed major depressive disorder (MDD). Pre-surgery history of MDD was found in 47.8% of patients, but was not associated with greater baseline cognitive impairments. Repeated measures revealed improved cognitive abilities 12 months after surgery. Pre-surgery history of MDD did not influence post-operative cognitive function. Pre-operative history of MDD did not limit post-operative cognitive improvements. Larger studies with extended follow-ups are needed to clarify our findings and identify factors (e.g. older age) that may modify cognitive changes following surgery.

Cognitive function is associated with impaired heart rate variability in ageing adults: the Irish longitudinal study on ageing wave one results

OBJECTIVE

To examine the independent association between heart rate variability (HRV) and cognitive performance, in a nationally representative population study of older adults.

METHODS

Cross-sectional analysis of wave 1 data from the Irish longitudinal study on ageing (TILDA) was performed. A subset of 4,763 participants who underwent ECG recording during resting and paced breathing periods were used for the analysis. HRV indices were divided into quintiles for comparison of values and cognitive performance was defined using the Montreal cognitive assessment (MOCA) score. Multivariate linear regression was used to model the association between cognition and different quintiles of each HRV index, after adjustment for covariates.

RESULTS

The mean age was 61.7 ± 8.3 years and 2,618 (55 %) were female. Lower quintiles of SDNN (P = 0.01-paced), LF (P = 0.001-paced), and LF:HF ratio (P = 0.049-paced) were significantly associated with lower MOCA scores (during both recording periods), independent of confounders. Sub-domains of MOCA responsible for the relationship were predominantly memory recall and language.

INTERPRETATION

Reduced HRV is significantly associated with lower cognitive performance at a population level in people aged 50 and older. This further strengthens the relationship between autonomic dysfunction and cognitive disorders.

Family history of Alzheimer's disease limits improvement in cognitive function after bariatric surgery

Background/Objective:

Bariatric surgery can reverse cognitive impairments associated with obesity. However, such benefits may be attenuated in individuals with a predisposing risk for cognitive impairment such as family history of Alzheimer’s disease.

Methods:

In all, 94 bariatric surgery participants completed a computerized cognitive test battery before and 12 weeks after surgery. Family history of Alzheimer’s disease was obtained through self-report.

Results:

In the overall sample, cognitive function improved in memory and attention/executive function 12 weeks post-surgery. Repeated measures showed similar rates of improvements in attention/executive function between patients with and without a family history of Alzheimer’s disease. In contrast, only individuals without a family history of Alzheimer’s disease exhibited post-operative improvements in memory. A family history of Alzheimer’s disease was associated with greater post-surgery rates of cognitive impairment.

Conclusions:

Family history of Alzheimer’s disease may limit post-surgery cognitive benefits. Future studies should examine whether weight loss can modify the course of cognitive decline in patients at-risk for Alzheimer’s disease.

Cellular and molecular mechanisms of immunomodulation in the brain through environmental enrichment

Recent studies on environmental enrichment (EE) have shown cytokines, cellular immune components [e.g., T lymphocytes, natural killer (NK) cells], and glial cells in causal relationship to EE in bringing out changes to neurobiology and behavior. The purpose of this review is to evaluate these neuroimmune mechanisms associated with neurobiological and behavioral changes in response to different EE methods. We systematically reviewed common research databases. After applying all inclusion and exclusion criteria, 328 articles remained for this review. Physical exercise (PE), a form of EE, elicits anti-inflammatory and neuromodulatory effects through interaction with several immune pathways including interleukin (IL)-6 secretion from muscle fibers, reduced expression of Toll-like receptors on monocytes and macrophages, reduced secretion of adipokines, modulation of hippocampal T cells, priming of microglia, and upregulation of mitogen-activated protein kinase phosphatase-1 in central nervous system. In contrast, immunomodulatory roles of other enrichment methods are not studied extensively. Nonetheless, studies showing reduction in the expression of IL-1β and tumor necrosis factor-α in response to enrichment with novel objects and accessories suggest anti-inflammatory effects of novel environment. Likewise, social enrichment, though considered a necessity for healthy behavior, results in immunosuppression in socially defeated animals. This has been attributed to reduction in T lymphocytes, NK cells and IL-10 in subordinate animals. EE through sensory stimuli has been investigated to a lesser extent and the effect on immune factors has not been evaluated yet. Discovery of this multidimensional relationship between immune system, brain functioning, and EE has paved a way toward formulating environ-immuno therapies for treating psychiatric illnesses with minimal use of pharmacotherapy. While the immunomodulatory role of PE has been evaluated extensively, more research is required to investigate neuroimmune changes associated with other enrichment methods.

Effects of chemokine receptor signalling on cognition-like, emotion-like and sociability behaviours of CCR6 and CCR7 knockout mice

Inflammation is regarded as an important mechanism of neuropsychiatric disorders. Chemokines, which are a part of the immune system, have effects on various aspects of brain function, but little is known about their effects on behaviour. We have compared the cognition-like behaviour (learning and spatial memory) of CCR6(-/-) and CCR7(-/-) mice with wild type (WT) C57BL/6 mice, in the Barnes maze, as well as a range of other behaviours, including exploratory, anxiety and depression-like behaviour, using a battery of tests. Levels of cytokines TNF-α, IL-1β and IL-6 were also measured. In the Barnes maze, CCR7(-/-) mice were shown to take longer to learn the location of the escape box on the 1st of 4 days of training. In the behavioural battery, CCR6(-/-) mice showed higher locomotor activity and lower anxiety in the open field test, and a lack of preference for social novelty in a sociability test. CCR7(-/-) mice behaved much like WT mice, although showed higher anxiety in Elevated Zero Maze. While baseline saccharin preference in a 2-bottle choice test, a test for anhedonia depression-like behaviour, was equal in all strains at baseline, weekly tests showed that both CCR6(-/-) and CCR7(-/-) mice developed a decreased preference for saccharin compared to WT over time. There were no differences between strains in any of the cytokines measured. These results suggest that chemokine receptors may play a role in cognition and learning behaviour, as well as anxiety and other behaviours, although the biological mechanisms are still unclear.

Prolonged systemic inflammation persistently modifies synaptic plasticity in the hippocampus: modulation by the stress hormones

Transient systemic inflammation has been shown to cause altered behavior both in humans and in laboratory animals through activation of microglia and heightened level of cytokines detected in the brain and in the body. Furthermore, both activated microglia and the increased cytokines level have been associated with the sudden clinical deterioration in demented people or in aged patients upon systemic inflammation. Whilst it is increasingly becoming clear the role of transient systemic inflammation in promoting dementia in aged individuals, it is still a matter of debate whether prolonged systemic inflammation might persistently modify the brain. In this study, we examined the influence of a systemic long term inflammatory event on synaptic plasticity. We report that while a short exposure to LPS produces transient deficit in long term potentiation (LTP) expression, systemic prolonged inflammation impairs LTP in slices of animals previously primed by a Complete Freund's adjuvant injection. Interestingly, steroids are able to modulate this effect: whereas glucocorticosteroid (GR) activation further reduces LTP, mineralocorticosteroid receptors (MR) activation promotes the full recovery of LTP. We believe that this research advances the current understandings on the role of the immune system in the onset and progression of cognitive deficits following long lasting systemic inflammation, and proposes possible insights on future strategies in order to prevent early dementia in these predisposed individuals.

Sydney Memory and Ageing Study: an epidemiological cohort study of brain ageing and dementia

Non-demented community-dwelling older adults aged 70-90 years (n = 1,037) randomly recruited from the electoral roll completed neuropsychological and medical assessments over six years. The overall prevalence of mild cognitive impairment (MCI) at baseline was 36.7%. Risk factors for MCI include APOE ε4 allele carrier status, high homocysteine, heart disease, poor odour identification, low visual acuity and low mental activity, but notable age and sex differences were observed. Neuropsychiatric symptoms were rare; depression was the most common and was associated with cognitive impairment in at least one domain as well as subsequent dementia 2 years later. Poorer cognitively demanding functional abilities were associated with cognitive impairment. Biomarkers for cognitive impairment and decline were identified. Inflammatory markers and plasma apolipoprotein levels were associated with poorer performance in the attention/processing speed domain. Measures of white matter lesions, white matter integrity, sulcal morphology and tractography were identified as novel biomarkers of early cognitive decline. Stronger deactivation in the posteromedial cortex with increasing memory load on functional MRI predicted future decline. Compared to previous reports, our prevalence rates of MCI were higher but rates of progression to dementia and reversion to normal were similar, as were risk factors for progression to dementia.

Obesity in aging exacerbates blood-brain barrier disruption, neuroinflammation, and oxidative stress in the mouse hippocampus: effects on expression of genes involved in beta-amyloid generation and Alzheimer's disease

There is growing evidence that obesity has deleterious effects on the brain and cognitive function in the elderly population. However, the specific mechanisms through which aging and obesity interact to promote cognitive decline remain unclear. To test the hypothesis that aging exacerbates obesity-induced cerebromicrovascular damage and neuroinflammation, we compared young (7 months) and aged (24 months) high fat diet-fed obese C57BL/6 mice. Aging exacerbated obesity-induced systemic inflammation and blood-brain barrier disruption, as indicated by the increased circulating levels of proinflammatory cytokines and increased presence of extravasated immunoglobulin G in the hippocampus, respectively. Obesity-induced blood-brain barrier damage was associated with microglia activation, upregulation of activating Fc-gamma receptors and proinflammatory cytokines, and increased oxidative stress. Treatment of cultured primary microglia with sera derived from aged obese mice resulted in significantly more pronounced microglia activation and oxidative stress, as compared with treatment with young sera. Serum-induced activation and oxidative stress were also exacerbated in primary microglia derived from aged animals. Hippocampal expression of genes involved in regulation of the cellular amyloid precursor protein-dependent signaling pathways, beta-amyloid generation, and the pathogenesis of tauopathy were largely unaffected by obesity in aged mice. Collectively, obesity in aging is associated with a heightened state of systemic inflammation, which exacerbates blood-brain barrier disruption. The resulting neuroinflammation and oxidative stress in the mouse hippocampus likely contribute to the significant cognitive decline observed in aged obese animals.

Macrophage inhibitory cytokine-1 is associated with cognitive impairment and predicts cognitive decline - the Sydney Memory and Aging Study

Higher levels of macrophage inhibitory cytokine-1, also known as growth differentiation factor 15 (MIC-1/GDF15), are associated with adverse health outcomes and all-cause mortality. The aim of this study was to examine the relationships between MIC-1/GDF15 serum levels and global cognition, five cognitive domains, and mild cognitive impairment (MCI), at baseline (Wave 1) and prospectively at 2 years (Wave 2), in nondemented participants aged 70-90 years. Analyses were controlled for age, sex, education, Framingham risk score, history of cerebrovascular accident, acute myocardial infarction, angina, cancer, depression, C-reactive protein, tumor necrosis factor-α, interleukins 6 and 12, and apolipoprotein ε4 genotype. Higher MIC-1/GDF15 levels were significantly associated with lower global cognition at both waves. Cross-sectional associations were found between MIC-1/GDF15 and all cognitive domains in Wave 1 (all P < 0.001) and between processing speed, memory, and executive function in Wave 2 (all P < 0.001). Only a trend was found for the prospective analyses, individuals with high MIC-1/GDF15 at baseline declined in global cognition, executive function, memory, and processing speed. However, when categorizing MIC-1/GDF15 by tertiles, prospective analyses revealed statistically significant lower memory and executive function in Wave 2 in those in the upper tertile compared with the lower tertile. Receiver operating characteristics (ROC) analysis was used to determine MIC-1/GDF15 cutoff values associated with cognitive decline and showed that a MIC-1/GDF15 level exceeding 2764 pg/ml was associated with a 20% chance of decline from normal to MCI or dementia. In summary, MIC-1/GDF15 levels are associated with cognitive performance and cognitive decline. Further research is required to determine the pathophysiology of this relationship.

Systemic inflammation in non-demented elderly human subjects: brain microstructure and cognition

The purpose of this study was to test the hypothesis that higher levels of systemic inflammation in a community sample of non-demented subjects older than seventy years of age are associated with reduced diffusion anisotropy in brain white matter and lower cognition. Ninety-five older persons without dementia underwent detailed clinical and cognitive evaluation and magnetic resonance imaging, including diffusion tensor imaging. Systemic inflammation was assessed with a composite measure of commonly used circulating inflammatory markers (C-reactive protein and tumor necrosis factor-alpha). Tract-based spatial statistics analyses demonstrated that diffusion anisotropy in the body and isthmus of the corpus callosum was negatively correlated with the composite measure of systemic inflammation, controlling for demographic, clinical and radiologic factors. Visuospatial ability was negatively correlated with systemic inflammation, and diffusion anisotropy in the body and isthmus of the corpus callosum was shown to mediate this association. The findings of the present study suggest that higher levels of systemic inflammation may be associated with lower microstructural integrity in the corpus callosum of non-demented elderly individuals, and this may partially explain the finding of reduced higher-order visual cognition in aging.

Association of IL-12p70 and IL-6:IL-10 ratio with autism-related behaviors in 22q11.2 deletion syndrome: a preliminary report

22q11.2 deletion syndrome (22q11DS) is a genetic disorder that conveys a significant risk for the development of social behavior disorders, including autism and schizophrenia. Also known as DiGeorge syndrome, 22q11DS is the second most common genetic disorder and is characterized by an elevated risk for immune dysfunction, up to 77% of individuals have an identifiable immune deficiency. We hypothesize that this immune dysfunction could contribute to the elevated risk of impaired social behavior seen in 22q11DS. The current study begins to elucidate these immune deficits and link them with the behavioral alterations associated with the disorder. Serum concentrations of a series of cytokines were examined, using a multiplex immunoassay, in sixteen individuals with 22q11DS and screened for autism-related behavior using the Autism Diagnostic Interview-Revised (ADI-R). This preliminary study examined correlations between specific immune proteins and each of the ADI-R algorithm scores (social, communication, and repetitive behavior). The inflammatory cytokine IL-1β, as well as the ratio between the inflammatory cytokine IL-6 and the anti-inflammatory cytokine IL-10, were correlated with social scores (r=0.851, p=0.004; r=0.580, p=0.018). In addition, the inflammatory cytokines interferon gamma and IL-12p70 were correlated with repetitive behaviors (r=0.795, p=0.033; r=0.774, p=0.002). Interestingly, IL-12 has been reported to be increased in autistic children. These data show a positive association between severity of autism-related behaviors and level of serum concentrations of inflammatory cytokines in individuals with 22q11DS, providing a basis for further inquiry.

NOX2 deficiency attenuates markers of adiposopathy and brain injury induced by high-fat diet

The consumption of high-fat/calorie diets in modern societies is likely a major contributor to the obesity epidemic, which can increase the prevalence of cancer, cardiovascular disease, and neurological impairment. Obesity may precipitate decline via inflammatory and oxidative signaling, and one factor linking inflammation to oxidative stress is the proinflammatory, pro-oxidant enzyme NADPH oxidase. To reveal the role of NADPH oxidase in the metabolic and neurological consequences of obesity, the effects of high-fat diet were compared in wild-type C57Bl/6 (WT) mice and in mice deficient in the NAPDH oxidase subunit NOX2 (NOX2KO). While diet-induced weight gains in WT and NOX2KO mice were similar, NOX2KO mice had smaller visceral adipose deposits, attenuated visceral adipocyte hypertrophy, and diminished visceral adipose macrophage infiltration. Moreover, the detrimental effects of HFD on markers of adipocyte function and injury were attenuated in NOX2KO mice; NOX2KO mice had improved glucose regulation, and evaluation of NOX2 expression identified macrophages as the primary population of NOX2-positive cells in visceral adipose. Finally, brain injury was assessed using markers of cerebrovascular integrity, synaptic density, and reactive gliosis, and data show that high-fat diet disrupted marker expression in WT but not NOX2KO mice. Collectively, these data indicate that NOX2 is a significant contributor to the pathogenic effects of high-fat diet and reinforce a key role for visceral adipose inflammation in metabolic and neurological decline. Development of NOX-based therapies could accordingly preserve metabolic and neurological function in the context of metabolic syndrome.

How predictive of dementia are peripheral inflammatory markers in the elderly?

Dementia is a huge public health concern today owing to the exponentially increasing number of older adults it affects each year, and there has been a large number of investigators looking at potential biomarkers of dementia. Peripheral inflammatory markers have emerged as one potential class of markers that may be useful in predicting those individuals at a greater risk of developing dementia, or in expounding the underlying mechanisms or pathways of this complex disease. Although some evidence has been promising, indicating that peripheral inflammatory markers are indeed crucial in brain changes that occur in both normal aging and in dementia, results have been mixed on their usefulness for predicting dementia or cognitive decline in older adults. Here, the authors present a review of existing studies investigating inflammatory markers as potential biomarkers of dementia, highlighting some strengths and limitations of the current research and discuss the future directions for this field.