Interleukin-6 and risk of cognitive decline: MacArthur studies of successful aging

Neck muscle cross-sectional area, brain volume and cognition in healthy older men: a cohort study

Background

Two important consequences of the normal ageing process are sarcopenia (the age-related loss of muscle mass and function) and age-related cognitive decline. Existing data support positive relationships between muscle function, cognition and brain structure. However, studies investigating these relationships at older ages are lacking and rarely include a measure of muscle size. Here we test whether neck muscle size is positively associated with cognition and brain structure in older men.

Methods

We studied 51 healthy older men with mean age 73.8 (sd 1.5) years. Neck muscle cross-sectional area (CSA) was measured from T1-weighted MR-brain scans using a validated technique. We measured multiple cognitive domains including verbal and visuospatial memory, executive functioning and estimated prior cognitive ability. Whole brain, ventricular, hippocampal and cerebellar volumes were measured with MRI. General linear models (ANCOVA) were performed.

Results

Larger neck muscle CSA was associated with less whole brain atrophy (t = 2.86, p = 0.01, partial eta squared 17%). Neck muscle CSA was not associated with other neuroimaging variables or current cognitive ability. Smaller neck muscle CSA was unexpectedly associated with higher prior cognition (t = −2.12, p < 0.05, partial eta squared 10%).

Conclusions

In healthy older men, preservation of whole brain volume (i.e. less atrophy) is associated with larger muscle size. Longitudinal ageing studies are now required to investigate these relationships further.

Daily exercise improves memory, stimulates hippocampal neurogenesis and modulates immune and neuroimmune cytokines in aging rats

We tested whether daily exercise modulates immune and neuroimmune cytokines, hippocampus-dependent behavior and hippocampal neurogenesis in aging male F344 rats (18mo upon arrival). Twelve weeks after conditioned running or control group assignment, the rats were trained and tested in a rapid water maze followed by an inhibitory avoidance task. The rats were BrdU-injected beginning 12days after behavioral testing and killed 3weeks later to quantify cytokines and neurogenesis. Daily exercise increased neurogenesis and improved immediate and 24h water maze discrimination index (DI) scores and 24h inhibitory avoidance retention latencies. Daily exercise decreased cortical VEGF, hippocampal IL-1β and serum MCP-1, GRO-KC and leptin levels but increased hippocampal GRO-KC and IL-18 concentrations. Serum leptin concentration correlated negatively with new neuron number and both DI scores while hippocampal IL-1β concentration correlated negatively with memory scores in both tasks. Cortical VEGF, serum GRO-KC and serum MCP-1 levels correlated negatively with immediate DI score and we found novel positive correlations between hippocampal IL-18 and GRO-KC levels and new neuron number. Pathway analyses revealed distinct serum, hippocampal and cortical compartment cytokine relationships. Our results suggest that daily exercise potentially improves cognition in aging rats by modulating hippocampal neurogenesis and immune and neuroimmune cytokine signaling. Our correlational data begin to provide a framework for systematically manipulating these immune and neuroimmune signaling molecules to test their effects on cognition and neurogenesis across lifespan in future experiments.

Adverse oral health and cognitive decline: the health, aging and body composition study

OBJECTIVES

To investigate the relationship between periodontal disease and cognitive decline.

DESIGN

Analysis of a prospective cohort study.

SETTING

The Health, Aging and Body Composition (Health ABC) Study.

PARTICIPANTS

One thousand fifty-three participants who were administered the Modified Mini-Mental State Examination (3MS) at Year 1 (baseline) and Year 3 and had participated in a comprehensive periodontal examination at Year 2.

MEASUREMENTS

The prospective association between a range of oral health parameters and cognitive function was examined. Decline in 3MS score from Year 3 to 5 was investigated in 947 (89.9%) participants. Covariates included age, sex, education, race, cardiovascular disease and risk, and depressive symptoms.

RESULTS

Most indicators of adverse oral health at Year 2 were associated with cognitive impairment based on averaged 3MS scores less than 80 for Years 1 and 3, but education and race substantially confounded these associations. Higher gingival index, a measure of gingival inflammation, at Year 2 remained independently associated with this definition of cognitive impairment and, in fully adjusted analyses, was also an independent predictor of a more-than-5-point cognitive decline from Year 3 to 5.

CONCLUSION

Periodontitis may be a risk factor for cognitive decline. Gingivitis is reversible, and periodontitis to some degree is preventable and controllable when manifest. Therefore, further research is needed to clarify potential underlying mechanisms and oral health interventions that might ameliorate cognitive decline.

Interleukin 6 plasma concentration associates with cognitive decline: the northern Manhattan study

BACKGROUND

Interleukin 6 (IL-6) is an inflammatory cytokine that has been associated with vascular disease and cognitive impairment, but few studies have examined these relationships in population-based studies that include Hispanic and Black people who often have a greater prevalence of vascular risk factors and are at an elevated risk of dementia than Whites. We examined relative elevations of plasma IL-6 concentrations in relation to cognitive decline in a stroke-free racially/ethnically diverse community-based sample from Northern Manhattan.

METHODS

We used mixed effects models to measure the effect of IL-6 on change in performance on the modified Telephone Interview for Cognitive Status (TICS-m) measured annually in our cohort, adjusting for sociodemographic and vascular risk factors.

RESULTS

There were 1,224 participants with IL-6 levels (median 1.5 pg/ml, interquartile range 0.83-2.57 pg/ml) and TICS-m data available (mean = 31.6 points, SD 6.5). The mean age was 71 (SD 9.3; 64% women, 59% Hispanic, 19% Black, 19% White) with 3,406 person-years and a median 3.0 years of follow-up (interquartile range 1.1-4.0 years). Participants with IL-6 levels above the median showed greater cognitive decline on the TICS-m compared to those with levels below the median, adjusting for sociodemographic and vascular factors (β = -0.17 points/year, p = 0.02). Decline on the TICS-m among participants with IL-6 above the median differed by age (p for interaction <0.001). There was no interaction by race/ethnicity, vascular risk factors, C-reactive protein, apolipoprotein ε4 allele status, or the metabolic syndrome among nondiabetics.

CONCLUSIONS

IL-6 associated with cognitive decline among older participants in this racially/ethnically diverse sample independent of other vascular risk factors and C-reactive protein.

Effects of minocycline on spatial learning, hippocampal neurogenesis and microglia in aged and adult mice

Age-related priming of microglia and release of inflammatory cytokines, such as interleukin-1β (IL-1β) and interleuekin-6 (IL-6) have been associated with deficits in cognitive function. The present study assessed whether treatment with minocycline could improve spatial cognition in aged mice, and whether these improvements in behavior were associated with reduced microglia activation and an enhancement in hippocampal neurogenesis. Adult (3 months) and aged (22 months) male BALB/c mice received minocycline in their drinking water or control mice received distilled water for 20 days. Mice received BrdU to label dividing cells on days 8-17. Spatial learning was measured using the water maze. Immunohistochemistry was conducted to measure number of BrdU positive neurons and number and size of microglia by detection of Iba-1 in the dentate gyrus molecular layer. Further, hippocampal samples were collected to measure changes in IL-1β, IL-6, and CD74 expression. The data show that aged mice have increased hippocampal expression of IL-1β, IL-6, and CD74 relative to adults. Minocycline treatment significantly improved acquisition of the water maze in aged mice but not adults. Minocycline reduced the average size of Iba-1 positive cells and total Iba-1 counts, but did not affect hippocampal cytokine gene expression. Minocycline increased neurogenesis in adults but not aged mice. Collectively, the data indicate that treatment with minocycline may recover some aspects of cognitive decline associated with aging, but the effect appears to be unrelated to adult hippocampal neurogenesis.

Isoflurane induces learning impairment that is mediated by interleukin 1β in rodents

Postoperative cognitive decline is a clinical syndrome. Volatile anesthetics are commonly used during surgery. It is conceivable that volatile anesthetics may contribute to postoperative cognitive decline. Isoflurane can impair cognitive functions of animals under certain conditions. However, the mechanisms for this impairment are not clear. Here, male 18-month old Fisher 344 rats or 10-week old mice were exposed to 1.2 or 1.4% isoflurane for 2 h. Our studies showed that isoflurane impaired the cognitive functions of the rats in Barnes maze. Isoflurane-exposed rats had reduced freezing behavior during the training sessions in the fear conditioning test. This isoflurane effect was attenuated by lidocaine, a local anesthetic with anti-inflammatory property. Rats that had training sessions and were exposed to isoflurane 30 min later had freezing behavior similar to that of control animals. Isoflurane increased the expression of interleukin 1β (IL-1β), interleukin-6 and activated caspase 3 in the hippocampus of the 18-month old rats. IL-1β positive staining was co-localized with that of NeuN, a neuronal marker. The increase of IL-1β and activated caspase 3 but not interleukin-6 was attenuated by lidocaine. Isoflurane also impaired the cognitive functions of 10-week old C57BL/6J mice and increased IL-1β in their hippocampi. However, isoflurane did not affect the cognitive functions of IL-1β deficient mice. Our results suggest that isoflurane impairs the learning but may not affect the recall of the aged rats. IL-1β may play an important role in this isoflurane effect.

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.

Relationship between interleukin-6 and ammonia in patients with minimal hepatic encephalopathy due to liver cirrhosis

AIM

  Previous studies have shown significantly elevated levels of interleukin (IL)-6 in cirrhotic patients with minimal hepatic encephalopathy (MHE), but the relationship between circulating levels of IL-6 and ammonia is unclear. The aim of this study is to investigate the relationship between both variables in cirrhotic patients with MHE.

METHODS

  Psychometric tests including number connection test part A (NCT-A) and digit symbol test (DST) were performed to diagnose MHE in 85 cirrhotic patients. Simultaneously, circulating levels of IL-6 and ammonia were measured.

RESULTS

  Thirty-two (37.6%) cirrhotic patients were diagnosed with MHE. IL-6 and ammonia were the independent predictors of the presence of MHE (P < 0.05 for both variables). Circulating levels of IL-6 and ammonia correlated with the severity of MHE represented by results of NCT-A (r = 0.56, P < 0.05 and r = 0.39, P < 0.05, respectively) and DST (r = -0.48, P < 0.05 and r = -0.47, P < 0.05, respectively). Moreover, there was a significant correlation between circulating levels of IL-6 and those of ammonia in patients with MHE (r = 0.61, P < 0.05), and a positive additive interaction was found between IL-6 and ammonia on the presence of MHE, with a significant synergy index of 1.51 (95% confidence interval = 1.12-3.46).

CONCLUSION

  The present study demonstrates a significant correlation and a positive additive interaction between IL-6 and ammonia in cirrhotic patients with MHE, suggesting that IL-6 may have a potential synergistic relationship with ammonia in the induction of MHE.

The role of glia in late-life depression

Late-life depression (LLD) has a complex and multifactoral etiology. There is growing interest in elucidating how glia, acting alone or as part of a glial-neuronal network, may contribute to the pathophysiology of depression. In this paper, we explore results from neuroimaging studies showing gray-matter volume loss in key frontal and subcortical structures implicated in LLD, and present the few histological studies that have examined neuronal and glial densities in these regions. Compared to results in younger people with depression, there appear to be age-dependent differences in neuronal pathology but the changes in glial pathology may be more subtle, perhaps reflecting a longer-term compensatory gliosis to earlier damage. We then consider the mechanisms by which both astrocytes and microglia may mediate and modulate neuronal dysfunction and possible degeneration in depression. These include a critical role in the response to peripheral inflammation and central microglial activation, as well as a key role in glutamate metabolism. Advances in our understanding of glia are highlighted, including the role of microglia as "electricians" of the brain and astrocytes as key communicating cells, an integral part of the tripartite synapse. Finally, implications for clinicians are discussed, including the consideration of glia as biomarkers for LLD and incorporation of glia into future therapeutic strategies.

A principal component model of medical health: implications for cognitive deficits and decline among adults in a population-based sample

Longitudinal blood- and cognitive data from 879 adults were analyzed to extract a multidimensional health structure for prediction of cognitive change. Six health components were identified and replicated at two waves. Following, cognitive outcomes were regressed on the health components. Large proportions of cognitive age related variations were accounted for by baseline health in both cross-sectional and prospective analyses. Less variation was accounted for when health change and cognitive change were contrasted. Cardiovascular health was particularly important for prediction of cognitive change. Our study underlines causal relations between health and cognitive functions, and suggests that some effects are long term.

Loneliness and stress-related inflammatory and neuroendocrine responses in older men and women

Loneliness is a predictor of mortality and increased cardiovascular morbidity. Inflammation is a potential pathway through which loneliness might impact health. The aim of the study was to investigate the relationship between loneliness and inflammatory interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1Ra) and monocyte chemotactic protein-1 (MCP-1) responses to standardized mental stress. A secondary purpose was to evaluate whether individual variations in cortisol responses influenced the hypothesised relationship between loneliness and inflammation. Saliva samples and blood were taken from 524 healthy middle-aged men and women from the Whitehall II cohort at baseline, immediately after the stress tasks and 45min later. Loneliness was measured using the revised UCLA loneliness scale. Greater loneliness was associated with larger IL-6 (p=0.044) and IL-1Ra (p=0.006) responses to psychological stress and higher MCP-1 (p<0.001) levels in women, independently of age, grade of employment, body mass index and smoking status. No associations were observed in men. Cortisol responsivity was inversely related to loneliness in women, with the odds of being a cortisol responder decreasing with increased loneliness independently of covariates (p=0.008). The impact of loneliness on health in women may be mediated in part through dysregulation of inflammatory and neuroendocrine systems.

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

Inflammation may contribute to cognitive decline and dementia. This study examined the cross-sectional relationships between markers of systemic inflammation (C-reactive protein, interleukins-1β, -6, -8, -10, -12, plasminogen activator inhibitor, serum amyloid A, tumour necrosis factor-α and vascular adhesion molecule-1) and cognitive function in 873 non-demented community-dwelling elderly participants aged 70-90 years. Regression analyses were performed to determine the relationships between cognitive domains and inflammatory markers, controlling for age, sex, education, cardiovascular risk factors, obesity and other metabolic factors, smoking, alcohol consumption, depression and presence of the apolipoprotein ε4 genotype. Regression analyses were repeated using four factors derived from a factor analysis of the cognitive tests. After Bonferroni correction for multiple testing, associations remained between raised levels of interleukin-12 and reduced performance in processing speed. Marked sex differences were noted in the abovementioned findings, with only females being significantly affected. Using the four factors derived from the factor analyses of cognitive test as dependent variables, interleukins-12 and -6 were both associated with the processing speed/executive function factor, even after controlling for relevant confounding factors. Thus, markers of systemic inflammation are related to cognitive deficits in a non-clinical community-dwelling elderly population, independent of depression, cardiovascular or metabolic risk factors, or presence of apolipoprotein ε4 genotype. Additional research is required to elucidate the pathophysiology and longitudinal development of these relationships.

Sleep disturbance induces neuroinflammation and impairment of learning and memory

Hospitalized patients can develop cognitive function decline, the mechanisms of which remain largely to be determined. Sleep disturbance often occurs in hospitalized patients, and neuroinflammation can induce learning and memory impairment. We therefore set out to determine whether sleep disturbance can induce neuroinflammation and impairment of learning and memory in rodents. Five to 6-month-old wild-type C57BL/6J male mice were used in the studies. The mice were placed in rocking cages for 24 h, and two rolling balls were present in each cage. The mice were tested for learning and memory function using the Fear Conditioning Test one and 7 days post-sleep disturbance. Neuroinflammation in the mouse brain tissues was also determined. Of the Fear Conditioning studies at one day and 7 days after sleep disturbance, twenty-four hour sleep disturbance decreased freezing time in the context test, which assesses hippocampus-dependent learning and memory; but not the tone test, which assesses hippocampus-independent learning and memory. Sleep disturbance increased pro-inflammatory cytokine IL-6 levels and induced microglia activation in the mouse hippocampus, but not the cortex. These results suggest that sleep disturbance induces neuroinflammation in the mouse hippocampus, and impairs hippocampus-dependent learning and memory in mice. Pending further studies, these findings suggest that sleep disturbance-induced neuroinflammation and impairment of learning and memory may contribute to the development of cognitive function decline in hospitalized patients.

Physical activity, obesity, and cognitive impairment among women with systemic lupus erythematosus

OBJECTIVE

To examine relationships of obesity and physical inactivity to cognitive impairment in women with systemic lupus erythematosus (SLE).

METHODS

Body composition was measured with dual x-ray absorptiometry (DXA) for 138 women with SLE. Obesity was defined by total percent body fat. Physical activity was ascertained with the self-reported International Physical Activity Questionnaire; inactivity was defined as expenditure of <600 metabolic equivalent minutes/week. Cognitive function was assessed with a 12-index neuropsychological battery. Impairment was defined as age-adjusted Z scores ≤1.5 SDs below the mean on 1 of 3 of tests completed. Scores were obtained for the total battery and for memory and executive function components. Multivariate analyses examined the relationship of obesity and physical activity, individually and combined, to cognitive impairment, controlling for education, race/ethnicity, disease activity, glucocorticoid use, and depression.

RESULTS

Fifteen percent of subjects were cognitively impaired, 28% were physically inactive, and 50% were obese. Five percent of active women were impaired on the executive function battery compared to 23% of those who were inactive (P = 0.003). Obese women were more likely to be impaired on the total battery (6% versus 23%; P = 0.007) and on the executive function portion (2% versus 19%) than nonobese women. In multivariate analysis, both inactivity and DXA-defined obesity were significantly associated with impairment in executive function (inactivity: odds ratio [OR] 9.4, 95% confidence interval [95% CI] 1.7-52.8; obesity: OR 14.8, 95% CI 1.4-151.0).

CONCLUSION

Both obesity and inactivity were significantly and independently associated with impairment in cognitive function. If longitudinal studies show that physical inactivity and obesity are precursors to cognitive impairment, these may become important targets for intervention.

Interleukin-6 trans-signaling in the senescent mouse brain is involved in infection-related deficits in contextual fear conditioning

Excessive production of pro-inflammatory cytokines in the senescent brain in response to peripheral immune stimulation is thought to induce behavioral pathology, however, few studies have examined if the increase in pro-inflammatory cytokines is accompanied by an increase in cytokine signaling. Here, we focused on IL-6 as a prototypic pro-inflammatory cytokine and used phosphorylated STAT3 as a marker of IL-6 signaling. In an initial study, IL-6 mRNA and the magnitude and duration of STAT3 activation were increased in the hippocampus of senescent mice compared to adults after i.p. injection of LPS. The LPS-induced increase in STAT3 activity was ablated in aged IL-6(-/-) mice, suggesting IL-6 is a key driver of STAT3 activity in the aged brain. To determine if IL-6 activated the classical or trans-signaling pathway, before receiving LPS i.p., aged mice were injected ICV with sgp130, an antagonist of the trans-signaling pathway. Importantly, the LPS-induced increases in both IL-6 and STAT3 activity in the hippocampus were inhibited by sgp130. To assess hippocampal function, aged mice were injected ICV with sgp130 and i.p. with LPS immediately after the acquisition phase of contextual fear conditioning, and immobility was assessed in the retention phase 48h later. LPS reduced immobility in aged mice, indicating immune activation interfered with memory consolidation. However, sgp130 blocked the deficits in contextual fear conditioning caused by LPS. Taken together, the results suggest IL-6 trans-signaling is increased in the senescent brain following peripheral LPS challenge and that sgp130 may protect against infection-related neuroinflammation and cognitive dysfunction in the aged.

The inhalation anesthetic isoflurane increases levels of proinflammatory TNF-α, IL-6, and IL-1β

Anesthetics have been reported to promote Alzheimer's disease (AD) neuropathogenesis by inducing β-amyloid protein accumulation and apoptosis. Neuroinflammation is associated with the emergence of AD. We therefore set out to determine the effects of the common anesthetic isoflurane on the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β, the proinflammatory cytokines, in vitro and in vivo, employing Western blot, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and reverse transcriptase polymerase chain reaction (RT-PCR). Here, we show that a clinically relevant isoflurane anesthesia increased the protein and messenger ribonucleic acid (mRNA) levels of TNF-α, IL-6, and IL-1β in the brain tissues of mice. The isoflurane anesthesia increased the amounts of TNF-α immunostaining positive cells in the brain tissues of mice, the majority of which were neurons. Furthermore, isoflurane increased TNF-α levels in primary neurons, but not microglia cells, of mice. Finally, isoflurane induced a greater degree of TNF-α increase in the AD transgenic mice than in the wild-type mice. These results suggest that isoflurane may increase the levels of proinflammatory cytokines, which may cause neuroinflammation, leading to promotion of AD neuropathogenesis.

Inflammatory markers and the risk of hip fracture: the Women's Health Initiative

Cytokines play a major role in bone remodeling in vitro and in animal models, with evidence supporting the involvement of inflammatory markers in the pathogenesis of osteoporosis. However, less is known about the longitudinal association of inflammatory markers with hip fracture. We tested whether high receptor levels of proinflammatory cytokines are associated with an increased risk of hip fracture in older women. We used a nested case-control study design from the Women's Health Initiative Observational Study (WHI-OS) and selected 400 cases with physician-adjudicated incident hip fractures and 400 controls matched on age, race, and date of blood draw. Participants were chosen from 39,795 postmenopausal women without previous hip fractures, not using estrogens or other bone-active therapies. Incident hip fractures (median follow-up 7.1 years) were verified by review of radiographs and confirmed by blinded central adjudicators. Hip fractures with a pathological cause were excluded. In multivariable models, the risk of hip fracture for subjects with the highest levels of inflammatory markers (quartile 4) compared with those with lower levels (quartiles 1, 2, and 3) was 1.43 (95% confidence interval [CI], 0.98-2.07) for interleukin-6 (IL-6) soluble receptor (SR), 1.40 (95% CI, 0.97-2.03) for tumor necrosis factor (TNF) SR1, and 1.56 (95% CI, 1.09-2.22) for TNF SR2. In subjects with all three markers in the highest quartile, the risk ratio of fracture was 2.76 (95% CI, 1.22-6.25) in comparison with subjects with 0 or 1 elevated marker(s) (p trend = 0.018). Elevated levels of inflammatory markers for all three cytokine-soluble receptors were associated with an increased risk of hip fractures in older women. Future clinical trials should test whether interventions to decrease inflammatory marker levels reduces hip fractures.

Association of grip strength with dementia in a Korean older population

BACKGROUND

Several studies have found that low grip strength is associated with dementia in Western populations. However, there have been few studies in Asian populations. This cross-sectional study aimed to examine whether grip strength is independently associated with dementia after controlling for other related factors in a Korean older population.

METHODS

One thousand thirty-eight community-dwelling older people aged 65 or over within a defined geographic area were screened for dementia. Data on grip strength, sit-to-stand score, body mass index (BMI), socio-demographic factors (age, gender, marital status, education), and medical conditions (diabetes, hypertension, heart disease, stroke) were collected. Dementia was diagnosed with the 10/66 dementia diagnostic algorithm.

RESULTS

Eleven percent of the participants were found to have dementia. After adjustment for other factors, grip strength (per 8-kg decrease) was independently associated with dementia (odds ratio, 1.59; 95% confidence interval, 1.19-2.14). Adjusted grip strength by BMI interaction terms showed marginal significance (p = 0.098); that is, older people with both reduced grip strength and low BMI were likely to be at higher risk for dementia.

CONCLUSIONS

Reduced grip strength was independently associated with dementia in a Korean older population. This association was partially influenced by BMI.

Interleukin-1α, interleukin-1β and tumor necrosis factor-α genetic variants and risk of dementia in the very old: evidence from the "Monzino 80-plus" prospective study

The association among single nucleotide polymorphisms in inflammatory genes as interleukin-1 alpha (IL-1α), interleukin-1 beta (IL-1β) or tumor necrosis factor alpha (TNF-α) and dementia has been explored mostly in Alzheimer's disease, while few data addressing their association with dementia in very old people are available. We performed a prospective, door-to-door population-based study of 80 years or older residents in eight municipalities of Varese province, Italy (the Monzino 80-plus study). No difference was found by a cross-sectional approach comparing IL-1α rs1800587, IL-1β rs3087258 and TNF-α rs1799724 genotypic and allelic frequencies between those affected and not affected by dementia. After a 5-year follow-up, the elderly carriers of T-allele of TNF-α rs1799724 were at an increased risk of dementia (p = 0.03). This association was no more significant adjusting for the apolipoprotein E epsilon-4 allele (APOE-ε4, p = 0.26), which was an independent predictor of dementia onset (p = 0.0002). In short, in this Italian population of oldest olds, dementia was associated to the APOE-ε4 allele only.

Contribution of hyperammonemia and inflammatory factors to cognitive impairment in minimal hepatic encephalopathy

To assess the contribution of hyperammonemia and inflammation to induction of mild cognitive impairment (or MHE). We analyzed the presence of mild cognitive impairment (CI) by using the PHES battery of psychometric tests and measured the levels of ammonia and of the inflammatory cytokines IL-6 and IL-18 in blood of patients with different types of liver or dermatological diseases resulting in different grades of hyperammonemia and/or inflammation. The study included patients with 1) liver cirrhosis, showing hyperammonemia and inflammation; 2) non-alcoholic fatty liver disease (NAFLD) showing inflammation but not hyperammonemia; 3) non-alcoholic steatohepatitis (NASH) showing inflammation and very mild hyperammonemia; 4) psoriasis, showing inflammation but not hyperammonemia; 5) keloids, showing both inflammation and hyperammonemia and 6) controls without inflammation or hyperammonemia. The data reported show that in patients with liver diseases, cognitive impairment may appear before progression to cirrhosis if hyperammonemia and inflammation are high enough. Five out of 11 patients with NASH, without liver cirrhosis, showed cognitive impairment associated with hyperammonemia and inflammation. Patients with keloids showed cognitive impairment associated with hyperammonemia and inflammation, in the absence of liver disease. Hyperammonemia or inflammation alone did not induce CI but the combination of certain levels of hyperammonemia and inflammation is enough to induce CI, even without liver disease.

Long-term assessment of inflammation and healthy aging in late life: the Cardiovascular Health Study All Stars

BACKGROUND

Associations of inflammation with age-related pathologies are documented; however, it is not understood how changes in inflammation over time impact healthy aging.

METHODS

We examined associations of long-term change in C-reactive protein (CRP) and interleukin-6 (IL-6) with concurrent onset of physical and cognitive impairment, subsequent cardiovascular disease (CVD), and mortality in 1,051 participants in the Cardiovascular Health Study All Stars Study. Biomarkers were measured in 1996-1997 and 2005-2006.

RESULTS

In 2005-2006, median age was 84.9 years, 63% were women and 17% non-white; 21% had at least a doubling in CRP over time and 23% had at least a doubling in IL-6. Adjusting for demographics, CVD risk factors, and 1996-1997 CRP level, each doubling in CRP change over 9 years was associated with higher risk of physical or cognitive impairment (odds ratio 1.29; 95% confidence interval 1.15, 1.45). Results were similar for IL-6 (1.45; 1.20, 1.76). A doubling in IL-6 change over time, but not CRP, was associated with incident CVD events; hazard ratio (95% confidence interval) 1.34 (1.03, 1.75). Doubling in change in each biomarker was individually associated with mortality (CRP: 1.12 [1.03, 1.22]; IL-6 1.39 [1.16, 1.65]). In models containing both change and 2005-2006 level, only level was associated with CVD events and mortality.

CONCLUSIONS

Although increases in inflammation markers over 9 years were associated with higher concurrent risk of functional impairment and subsequent CVD events and mortality, final levels of each biomarker appeared to be more important in determining risk of subsequent events than change over time.

Relationship between circulating cytokine levels and physical or psychological functioning in patients with advanced cancer

OBJECTIVE

To investigate the relation between functional impairments of cancer patients and circulating cytokines using a multiplex technique.

DESIGN AND METHODS

50 patients with cancer were assessed using the quality of life (QOL) questionnaire. 27 plasma cytokine levels were determined by using the Bio-Plex array system. The relation to QOL scores was assessed using Chi-square test for categorical variables and univariate linear regression analysis for cytokine levels.

RESULTS

Multivariate analysis showed that interleukin-6 (IL-6) level is a significant independent determinant of physical (β=-0.238, P=0.0126) and cognitive functioning (β=-0.462, P=0.0006) and that vascular endothelial growth factor (VEGF) level is a significant independent determinant of emotional functioning (β=-0.414, P=0.039).

CONCLUSION

This study, in which 27 cytokines are simultaneously tested with cutting edge technology, demonstrates that plasma IL-6 and VEGF are significant independent determinants of functional impairments in patients with cancer.

C-reactive protein is related to memory and medial temporal brain volume in older adults

Recent research suggests a central role for inflammatory mechanisms in cognitive decline that may occur prior to evidence of neurodegeneration. Limited information exists, however, regarding the relationship between low-grade inflammation and cognitive function in healthy older adults. This study examined the relation between inflammation, verbal memory consolidation, and medial temporal lobe volumes in a cohort of older community-dwelling subjects. Subjects included 141 functionally intact, community-dwelling older adults with detectable (n=76) and undetectable (n=65) levels of C-reactive protein. A verbal episodic memory measure was administered to all subjects, and measures of delayed recall and recognition memory were assessed. A semiautomated parcellation program was used to analyze structural MRI scans. On the episodic memory task, analysis of covariance revealed a significant CRP group by memory recall interaction, such that participants with detectable levels of CRP evidenced worse performance after a delay compared to those with undetectable levels of CRP. Individuals with detectable CRP also demonstrated lower performance on a measure of recognition memory. Imaging data demonstrated smaller left medial temporal lobe volumes in the detectable CRP group as compared with the undetectable CRP group. These findings underscore a potential role for inflammation in cognitive aging as a modifiable risk factor.

Gut memories: towards a cognitive neurobiology of irritable bowel syndrome

The brain and the gut are engaged in continual crosstalk along a number of pathways collectively termed the 'brain-gut axis'. Over recent years it has become increasingly clear that dysregulation of the axis at a number of levels can result in disorders such as irritable bowel syndrome (IBS). With recent advances in neuroimaging technologies, insights into the neurobiology of IBS are beginning to emerge. However the cognitive neurobiology of IBS has remained relatively unexplored to date. In this review we summarise the available data on cognitive function in IBS. Moreover, we specifically address three key pathophysiological factors, namely; stress, immune activation and chronic pain, together with other factors involved in the manifestation of IBS, and explore how each of these components may impact centrally, what neurobiological mechanisms might be involved, and consider the implications for cognitive functioning in IBS. We conclude that each factor addressed could significantly impinge on central nervous system function, supporting the view that future research efforts must be directed towards a detailed assessment of cognitive function in IBS.

The association of genetic variants in interleukin-1 genes with cognition: findings from the cardiovascular health study

The inflammatory cytokine interleukin-1 (IL1) potentially plays a role in cognitive deterioration through pathology due to a dementing disorder or due to an aging process. Study of genetic variants in the IL1 genes has been mostly limited to diseases such as Alzheimer's, however, there may be benefit to studying a continuous measure of cognition. Using data from the Cardiovascular Health Study, we evaluate genetic variation in the genes encoding inflammatory agonists IL1A and IL1B, and the antagonist IL1RN, with repeated measures of global cognition (3MS) and processing speed (DSST), using mixed effects models. We found statistically significant minor allele SNP associations with baseline performance on the 3MS in the IL1RN gene for Caucasians (rs17042917: beta=0.47, 95%CI=0.09, 0.85, p=0.016; rs4251961: beta=-0.36, 95%CI=-0.13,-0.60, p=0.0027; rs931471: beta=0.39, 95%CI=0.13, 0.65, p=0.0032), and the IL1B gene for African Americans (rs1143627: beta=1.6, 95%CI=0.48, 2.8; p=0.006 and rs1143634: beta=2.09, 95%CI=0.39, 3.8; p=0.016). Associations appear to be weaker in a subgroup with higher education level. Upon removing those diagnosed with dementia, effect sizes and statistical significance attenuated. These results provide supporting evidence that genetic variants in IL1 genes may be involved in inflammatory-related lowered cognition, that higher education may modify genetic predisposition, and that these associations may be driven by a dementia process.

Contribution of hyperammonemia and inflammatory factors to cognitive impairment in minimal hepatic encephalopathy

To assess the contribution of hyperammonemia and inflammation to induction of mild cognitive impairment (or MHE). We analyzed the presence of mild cognitive impairment (CI) by using the PHES battery of psychometric tests and measured the levels of ammonia and of the inflammatory cytokines IL-6 and IL-18 in blood of patients with different types of liver or dermatological diseases resulting in different grades of hyperammonemia and/or inflammation. The study included patients with 1) liver cirrhosis, showing hyperammonemia and inflammation; 2) non-alcoholic fatty liver disease (NAFLD) showing inflammation but not hyperammonemia; 3) non-alcoholic steatohepatitis (NASH) showing inflammation and very mild hyperammonemia; 4) psoriasis, showing inflammation but not hyperammonemia; 5) keloids, showing both inflammation and hyperammonemia and 6) controls without inflammation or hyperammonemia. The data reported show that in patients with liver diseases, cognitive impairment may appear before progression to cirrhosis if hyperammonemia and inflammation are high enough. Five out of 11 patients with NASH, without liver cirrhosis, showed cognitive impairment associated with hyperammonemia and inflammation. Patients with keloids showed cognitive impairment associated with hyperammonemia and inflammation, in the absence of liver disease. Hyperammonemia or inflammation alone did not induce CI but the combination of certain levels of hyperammonemia and inflammation is enough to induce CI, even without liver disease.

Habitual sugar intake and cognitive function among middle-aged and older Puerto Ricans without diabetes

Intake of added sugars, mainly fructose and sucrose, has been associated with risk factors for cognitive impairment, such as obesity, the metabolic syndrome and type 2 diabetes. The objective of this analysis was to examine whether habitual intakes of total sugars, added sugars, sugar-sweetened beverages or sweetened solid foods are associated with cognitive function. The present study included 737 participants without diabetes, aged 45-75 years, from the Boston Puerto Rican Health Study, 2004-9. Cognitive function was measured with a battery of seven tests: Mini-Mental State Examination (MMSE), word list learning, digit span, clock drawing, figure copying, and Stroop and verbal fluency tests. Usual dietary intake was assessed with a validated FFQ. Greater intakes of total sugars, added sugars and sugar-sweetened beverages, but not of sugar-sweetened solid foods, were significantly associated with lower MMSE score, after adjusting for covariates. Adjusted OR for cognitive impairment (MMSE score < 24) were 2.23 (95 % CI 1.24, 3.99) for total sugars and 2.28 (95 % CI 1.26, 4.14) for added sugars, comparing the highest with lowest intake quintiles. Greater intake of total sugars was also significantly associated with lower word list learning score. In conclusion, higher sugar intake appears to be associated with lower cognitive function, but longitudinal studies are needed to clarify the direction of causality.

The inflammation hypothesis in geriatric depression

BACKGROUND

A large body of research has focused on "mediating mechanisms" and predisposing brain abnormalities to geriatric depression, but little is known about its etiology. This paper examines whether age-related and comorbid disease-related immune deregulation is an etiologic contributor to geriatric depression.

METHODS

This article reviews findings on neuroinflammation during the aging process and depression as well as studies of anti-inflammatory actions of classical antidepressants and antidepressant actions of anti-inflammatory agents.

RESULTS

Aging results in increased peripheral immune responses, impaired peripheral-CNS immune communication, and a shift of the CNS into a pro-inflammatory state. These exaggerated and prolonged immune responses may lead to changes in the function of emotional and cognitive networks pertinent to geriatric depression and to behavioral changes reminiscent of the depressive and cognitive symptoms of geriatric depression. Some antidepressants may reduce the expression of inflammation markers. Limited data suggest that some anti-inflammatory agents may have antidepressant properties.

CONCLUSIONS

A synthesis of available findings suggests that aging-related and comorbid disease-related inflammatory processes may promote changes in the neural systems predisposing to geriatric depression or facilitating metabolic changes that mediate depressive syndromes. The "inflammation hypothesis" in geriatric depression cannot be tested in its entirety, but it can lead to testable hypotheses and data on mechanisms by which inflammatory processes promote geriatric depression. The significance of such an effort is that it may lead to a novel treatment development model bringing to bear recent advances of anti-inflammatory pharmacology to the treatment of depressed elderly patients.

Markers of inflammation in midlife women with intimate partner violence histories

BACKGROUND

Lifetime occurrence of intimate partner violence (IPV) in women has been associated with increased prevalence of aging-related chronic diseases, including those with a pathophysiology involving inflammation. To begin to identify potential biologic mediators of this relationship, this cross-sectional study examined associations between past IPV and circulating levels of C-reactive protein (CRP) and interleukin-6 (IL-6)-measures linked with emergence of aging-related diseases-along with in vitro IL-6 production by peripheral blood mononuclear cells (PBMC) stimulated with either phytohemagglutinin A (PHA) or lipopolysaccharide (LPS).

METHODS

Apparently healthy, midlife women with divorce histories were recruited from the community. Histories of intimate partner psychological aggression, physical assault, sexual coercion, and stalking were assessed, along with current depression, posttraumatic stress symptoms, and health-related characteristics. At two visits, blood was drawn for assessment of biologic measures; measures were averaged across visits.

RESULTS

In this sample (n=68), a history of being stalked was significantly positively correlated with CRP levels; in a multiple regression analysis that included body mass index (BMI) and current symptoms, this association was attenuated by adjusting for BMI. Physical assault history was significantly negatively correlated with PHA-stimulated IL-6 production. This was most apparent for severe assault and was not accounted for by BMI or symptoms.

CONCLUSIONS

IPV histories remitted for an average of 10 years were associated with biologic mediators of inflammation. The profile was not uniformly proinflammatory, suggesting that in situations of traumatic or chronic stress, different aspects of the inflammatory response are differentially regulated and subjected to diverse compensatory mechanisms.

Diet and Alzheimer's disease risk factors or prevention: the current evidence

Preventing or postponing the onset of Alzheimer's disease (AD) and delaying or slowing its progression would lead to a consequent improvement of health status and quality of life in older age. Elevated saturated fatty acids could have negative effects on age-related cognitive decline and mild cognitive impairment (MCI). Furthermore, at present, epidemiological evidence suggests a possible association between fish consumption, monounsaturated fatty acids and polyunsaturated fatty acids (PUFA; in particular, n-3 PUFA) and a reduced risk of cognitive decline and dementia. Poorer cognitive function and an increased risk of vascular dementia (VaD) were found to be associated with a lower consumption of milk or dairy products. However, the consumption of whole-fat dairy products may be associated with cognitive decline in the elderly. Light-to-moderate alcohol use may be associated with a reduced risk of incident dementia and AD, while for VaD, cognitive decline and predementia syndromes, the current evidence is only suggestive of a protective effect. The limited epidemiological evidence available on fruit and vegetable consumption and cognition generally supports a protective role of these macronutrients against cognitive decline, dementia and AD. Only recently, higher adherence to a Mediterranean-type diet was associated with decreased cognitive decline, although the Mediterranean diet (MeDi) combines several foods, micro- and macro-nutrients already separately proposed as potential protective factors against dementia and predementia syndromes. In fact, recent prospective studies provided evidence that higher adherence to a Mediterranean-type diet could be associated with slower cognitive decline, reduced risk of progression from MCI to AD, reduced risk of AD and a decreased all-cause mortality in AD patients. These findings suggested that adherence to the MeDi may affect not only the risk of AD, but also of predementia syndromes and their progression to overt dementia. Based on the current evidence concerning these factors, no definitive dietary recommendations are possible. However, following dietary advice for lowering the risk of cardiovascular and metabolic disorders, high levels of consumption of fats from fish, vegetable oils, nonstarchy vegetables, low glycemic index fruits and a diet low in foods with added sugars and with moderate wine intake should be encouraged. Hopefully this will open new opportunities for the prevention and management of dementia and AD.

Cognitive and emotional alterations are related to hippocampal inflammation in a mouse model of metabolic syndrome

Converging clinical data suggest that peripheral inflammation is likely involved in the pathogenesis of the neuropsychiatric symptoms associated with metabolic syndrome (MetS). However, the question arises as to whether the increased prevalence of behavioral alterations in MetS is also associated with central inflammation, i.e. cytokine activation, in brain areas particularly involved in controlling behavior. To answer this question, we measured in a mouse model of MetS, namely the diabetic and obese db/db mice, and in their healthy db/+ littermates emotional behaviors and memory performances, as well as plasma levels and brain expression (hippocampus; hypothalamus) of inflammatory cytokines. Our results shows that db/db mice displayed increased anxiety-like behaviors in the open-field and the elevated plus-maze (i.e. reduced percent of time spent in anxiogenic areas of each device), but not depressive-like behaviors as assessed by immobility time in the forced swim and tail suspension tests. Moreover, db/db mice displayed impaired spatial recognition memory (hippocampus-dependent task), but unaltered object recognition memory (hippocampus-independent task). In agreement with the well-established role of the hippocampus in anxiety-like behavior and spatial memory, behavioral alterations of db/db mice were associated with increased inflammatory cytokines (interleukin-1β, tumor necrosis factor-α and interleukin-6) and reduced expression of brain-derived neurotrophic factor (BDNF) in the hippocampus but not the hypothalamus. These results strongly point to interactions between cytokines and central processes involving the hippocampus as important contributing factor to the behavioral alterations of db/db mice. These findings may prove valuable for introducing novel approaches to treat neuropsychiatric complications associated with MetS.

C-reactive protein and genetic variants and cognitive decline in old age: the PROSPER study

BACKGROUND

Plasma concentrations of C-reactive protein (CRP), a marker of chronic inflammation, have been associated with cognitive impairment in old age. However, it is unknown whether CRP is causally linked to cognitive decline.

METHODS AND FINDINGS

Within the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) trial, with 5680 participants with a mean age of 75 years, we examined associations of CRP levels and its genetic determinants with cognitive performance and decline over 3.2 years mean follow-up. Higher plasma CRP concentrations were associated with poorer baseline performance on the Stroop test (P = 0.001) and Letter Digit Tests (P<0.001), but not with the immediate and delayed Picture Learning Test (PLT; both P>0.5). In the prospective analyses, higher CRP concentrations associated with increased rate of decline in the immediate PLT (P = 0.016), but not in other cognitive tests (all p>0.11). Adjustment for prevalent cardiovascular risk factors and disease did not change the baseline associations nor associations with cognitive decline during follow-up. Four haplotypes of CRP were used and, compared to the common haplotype, carrierships associated strongly with levels of CRP (all P<0.007). In comparison to strong associations of apolipoprotein E with cognitive measures, associations of CRP haplotypes with such measures were inconsistent.

CONCLUSION

Plasma CRP concentrations associate with cognitive performance in part through pathways independent of (risk factors for) cardiovascular disease. However, lifelong exposure to higher CRP levels does not associate with poorer cognitive performance in old age. The current data weaken the argument for a causal role of CRP in cognitive performance, but further study is warranted to draw definitive conclusions.

Association of cognitive performance with interleukin-6 receptor Asp358Ala polymorphism in healthy adults

Wechsler adult intelligence scale-revised was performed in 576 healthy adults to examine whether a functional polymorphism (Asp358Ala) of the IL-6 receptor (IL-6R) gene is associated with cognitive performance. Verbal intelligence quotient in Asp homozygotes was significantly higher compared to Ala carriers (P = 0.005). Compared to Ala carriers, Asp homozygotes performed better in the verbal subtests requiring long-term memory stores. Elevated IL-6 and soluble IL-6R levels in Ala carriers may have negative impact on acquiring verbal cognitive ability requiring long-term memory.

Physical frailty predicts future cognitive decline - a four-year prospective study in 2737 cognitively normal older adults

OBJECTIVE

To examine the association between baseline frailty measurements and cognitive function 4 years later.

DESIGN

Prospective observational study.

SETTING

Community.

PARTICIPANTS

Two thousand seven hundred and thirty seven cognitively normal older adults.

MEASUREMENT

The appendicular muscle mass (ASM), hand grip strength, timed chair-stand test, walking speed and step length were measured at baseline. The Mini-mental state examination (MMSE) was administered at baseline and 4 years later.

RESULTS

In men, all baseline frailty measurements, namely, being underweight, lower ASM, weaker grip strength, slower chair-stand test, shorter step length, slower timed walk were significantly associated with a lower MMSE score 4 years afterwards. After adjustment for age, years of education and baseline MMSE score, ASM and timed walk became insignificant. In women, all frailty measurements except underweight and low ASM were significantly associated with MMSE score 4 years later. Moreover, only weaker grip strength persisted to be significant after adjustment for age, years of education and baseline MMSE score.

CONCLUSION

Physical frailty, as represented by being underweight, weaker grip strength, slower chair-stand test, shorter step-length in men and weaker grip strength in women, was associated with cognitive decline over a four year period.

Different models of frailty in predementia and dementia syndromes

Dementia is an increasingly common disease in the aging population, and the numbers are expected to rise exponentially in coming years. Therefore, there is a critical need to potentially individualize new strategies able to prevent and to slow down the progression of predementia and dementia syndromes. Despite a substantial increase in the epidemiological and clinical evidence on frailty, there is no consensus on its definition or on what criteria should be used to identify older individuals with frailty. Frailty appears to be a nonspecific state of vulnerability, which reflects multisystem physiological change. In fact, current thinking is that not only physical but also psychological, cognitive and social factors contribute to this multidimensional syndrome and need to be taken into account in its definition and treatment. Cognition has already been considered as a component of frailty, and it has been demonstrated that it is associated with adverse health outcomes. In a recent population-based study, physical frail demented patients were at higher risk of all-cause mortality over 3- and 7-year follow-up periods. Several studies have also reported that physical frailty is associated with low cognitive performance, incidence of Alzheimer's disease (AD), and mild cognitive impairment, and AD pathology in older persons with and without dementia. Most frailty instruments use a dichotomous scoring system classifying a person as either frail or not frail, while a continuous or an ordinal scoring system on multiple levels would be preferable to be used as an outcome measure. Recently, a Multidimensional Prognostic Index (MPI), derived from a standardized comprehensive geriatric assessment, was effective in predicting short- and long-term mortality risk in hospitalized patients with dementia. Overall taken together these findings supported the concept that outcome measures linked to multidimensional impairment may be extremely important in making clinical decisions, especially for monitoring drug treatment in randomized clinical trials also for predementia and dementia syndromes.

A transdisciplinary perspective of chronic stress in relation to psychopathology throughout life span development

The allostatic load (AL) model represents an interdisciplinary approach to comprehensively conceptualize and quantify chronic stress in relation to pathologies throughout the life cycle. This article first reviews the AL model, followed by interactions among early adversity, genetics, environmental toxins, as well as distinctions among sex, gender, and sex hormones as integral antecedents of AL. We next explore perspectives on severe mental illness, dementia, and caregiving as unique human models of AL that merit future investigations in the field of developmental psychopathology. A complimenting transdisciplinary perspective is applied throughout, whereby we argue that the AL model goes beyond traditional stress–disease theories toward the advancement of person-centered research and practice that promote not only physical health but also mental health.

Inflammatory markers and neuropsychological functioning: the Framingham Heart Study

BACKGROUND/AIMS

We hypothesized that inflammatory markers are cross-sectionally and longitudinally associated with neuropsychological indicators of early ischemia and Alzheimer's disease.

METHODS

Framingham Offspring Study participants, free of clinical stroke or dementia (n = 1,878; 60 ± 9 years; 54% women), underwent neuropsychological assessment and ascertainment of 11 inflammatory markers. Follow-up neuropsychological assessments (6.3 ± 1.0 years) were conducted on 1,352 of the original 1,878 participants.

RESULTS

Multivariable linear regression related the inflammatory markers to cross-sectional performance and longitudinal change in neuropsychological performances. Secondary models included a twelfth factor, tumor necrosis factor-α (TNF-α), available on a subset of the sample (n = 1,393 cross-sectional; n = 1,213 longitudinal). Results suggest a few modest cross-sectional inflammatory and neuropsychological associations, particularly for tests assessing visual organization (C-reactive protein, p = 0.007), and a few modest relations between inflammatory markers and neuropsychological change, particularly for executive functioning (TNF-α, p = 0.004). Secondary analyses suggested that inflammatory markers were cross-sectionally (TNF-α, p = 0.004) related to reading performance.

CONCLUSIONS

Our findings are largely negative, but suggest that specific inflammatory markers may have limited associations with poorer cognition and reading performance among community-dwelling adults. Because of multiple testing concerns, our limited positive findings are offered as hypothesis generating and require replication in other studies.

Inflammatory markers in population studies of aging

PURPOSE

To review findings from major epidemiologic studies regarding risk factors for and consequences of elevated markers of inflammation in older adults.

RESULTS

Most large, current epidemiologic studies of older adults have measured serum interleukin-6 (IL-6), C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-alpha) and some studies also include more extensive batteries of measures including soluble receptors. There are few defined risk factors for the modest elevations in inflammatory markers seen with aging. These include visceral adiposity, lower sex steroid hormones, smoking, depression and periodontal disease. Of the markers assessed, IL-6 is most robustly associated with incident disease, disability and mortality.

CONCLUSION

Though correlated with age, the etiology of elevated inflammatory markers remains incompletely defined. Inflammation, especially IL-6 may be a common cause of multiple age-related diseases or a final common pathway by which disease leads to disability and adverse outcomes in older adults. Future research targeting inflammation should examine these pathways.

An evaluation of analytical approaches for understanding change in cognition in the context of aging and health

OBJECTIVES

In this article, we discuss the importance of studying the relationship between health and cognitive function, and some of the methods with which this relationship has been studied.

METHODS

We consider the challenges involved, in particular operationalization of the health construct and causal inference in the context of observational data. We contrast the approaches taken, and review the questions addressed: whether health and cognition are associated, whether changes in health are associated with changes in cognition, and the degree of interdependency among their respective trajectories.

RESULTS

A variety of approaches for understanding the association between cognition and health in aging individuals have been used. Much of the literature on cognitive change and health has relied on methods that are based at least in part on the reorganization of between-person differences (e.g., cross-lag analysis) rather than relying more fully on analysis of within-person change and joint analysis of individual differences in within-person change in cognition and health.

DISCUSSION

We make the case for focusing on the interdependency between within-person changes in health and cognition and suggest methods that would support this.

Elevated postoperative inflammatory biomarkers are associated with short- and medium-term cognitive dysfunction after coronary artery surgery

PURPOSE

We tested the hypothesis that elevated postoperative interleukin-6 (IL-6) and C-reactive protein (CRP) concentrations are associated with short- and medium-term impairment of cognitive functions in patients after coronary artery surgery using cardiopulmonary bypass.

METHODS

Eighty-six age- and education-balanced patients ≥55 years of age undergoing elective coronary artery bypass surgery with cardiopulmonary bypass and 28 nonsurgical controls with coronary artery disease were enrolled. Recent verbal and nonverbal memory and executive functions were assessed before surgery and at 1 week and 3 months after surgery using a cognitive test battery. IL-6 concentrations were measured before surgery and 4 h after cardiopulmonary bypass, and CRP concentrations were measured before surgery and at 24 and 72 h after anesthetic induction. Overall cognitive function between high and low biomarker concentration groups was analyzed by the Wilcoxon rank-sum test.

RESULTS

Recent memory was at least 1 standard deviation (SD) impaired at 1 week and 3 months in the high-CRP compared with low-CRP and in the high-IL-6 compared with low-IL-6 concentration groups. Overall cognitive function was significantly (P = 0.04 and P = 0.01, respectively) different between the high- and low-CRP concentration groups (CRP assayed 24 h after anesthetic induction) at both 1 week and 3 months. Overall cognitive function was also significantly (P = 0.04) different between the high and low-IL-6 concentration groups at 1 week after surgery.

CONCLUSION

The results suggest that elevated postoperative IL-6 and CRP concentrations are associated with the subsequent development of short- and medium-term impairment of cognitive functions after coronary artery surgery.

Immunity, aging, and geriatric depression

Inflammatory processes are likely to play a causal role in geriatric depression. Geriatric depression occurs in the context of illnesses in which inflammatory processes are part of the pathogenesis. Both aging and depression are associated with immune responses, and the connectivity among mood-regulating structures may be modulated by inflammatory responses. Geriatric depression exacerbates the symptoms of comorbid disorders. Geriatric depression often occurs in persons exposed to chronic stress, a state precipitating geriatric depression and triggering proinflammatory responses. The successful treatment of comorbid conditions that increase central nervous system inflammatory responses has general health benefits and should be part of clinical practice.

Brief report: preoperative frailty in older surgical patients is associated with early postoperative delirium

We investigated whether preoperative frailty among older noncardiac surgical patients provides information about the development of postoperative delirium that is in addition to traditional geriatric risk factors. One-third of patients had a frailty score ≥3, which is considered "frail" in others' research. Twenty-five percent of patients developed postoperative delirium, which was measured using the confusion assessment method. Multivariable logistic regression showed that age, activities of daily living dependence, instrumental activities of daily living dependence, and cognitive functioning did not contribute significantly to the prediction of postoperative delirium. Only preoperative symptoms of depression (odds ratio=1.42; 95% confidence interval=1.06-1.91; P=0.018) and the frailty score (odds ratio=1.84; 95% confidence interval=1.07-3.1; P=0.028) were independently associated with the development of postoperative delirium.

Dietary inflammation factor rating system and risk of Alzheimer disease in elders

It has been suggested that inflammation is involved in Alzheimer disease (AD) pathogenesis. The aim of this study is to evaluate the association between inflammatory aspects of diet and incident AD risk. About 2258 nondemented elderly (age ≥ 65) in New York who provided dietary information at baseline were followed-up prospectively for AD development. We examined the composite total Inflammation Factor Rating (tIFR), as a measure of inflammatory impact of foods, in relation with (i) serum level of high-sensitivity C-reactive protein (hsCRP) and (ii) risk of incident AD using Cox proportional hazard model. The tIFR was not associated with serum hsCRP level. After an average of 4.0 years of follow-up, 262 participants developed incident AD. The tIFR was not associated with AD risk: compared with the lowest tertile of tIFR (most proinflammatory), hazard ratios (95% confidence interval) for the highest tertile (most anti-inflammatory) was 0.97 (0.69-1.35) (P-for-trend=0.71), in the adjusted model. We conclude that tIFR might not be a biologically relevant measure of the inflammatory impact of the diet. In addition, although it remains possible that tIFR might be related with some other aspects of inflammation not captured by hsCRP, lack of association with AD risk suggests its limited clinical utility.

Cytokines and memory across the mature life span of women

Increasing evidence suggests a role of the immune system in modulation of cognition, but details on affected memory systems are largely lacking. We therefore aimed to study the relation between selected cytokines and subsets of memory, and the impact of age in these relations. From a random population-based sample (the Betula Prospective Cohort Study), 298 women (age 45-90) were studied in terms of episodic recall and recognition, semantic fluency and knowledge, and prospective memory. Circulating cytokines of relevance for cognition and aging were measured with ELISA. Levels of interleukin (IL)-6 and sIL-2R were significantly and negatively associated with most cognitive variables, while the opposite was true for IL-1β. Age shared substantial variance with both cytokines and memory, and turned most correlations non-significant when controlled for together with education, BMI and presence of disease. Interactions between age and cytokines were further analyzed in multiple regressions. For IL-6, significant negative interactions with age were found for semantic fluency (p<0.05) and prospective memory (p<0.01), and for sIL-2R in predicting semantic knowledge (p<0.05), indicating an increased negative impact of these cytokines on memory with increasing age. In conclusion, the study indicates a relation between cytokines and memory that appears to be largely mediated by age, and supports the suggestion that cytokine dysregulation with higher age may interact with cognitive aging.

Human anelloviruses and the central nervous system

Torque teno virus and related anelloviruses are a recent addition to the list of agents that cause chronic productive infections and high levels of plasma viraemia in humans. Many aspects of the natural history and pathogenesis of these under many respects surprising viruses are still poorly understood. In this review, we briefly outline the general properties of anelloviruses, examine what is currently known about the interactions they establish with the central nervous system (CNS), and discuss the possible pathological consequences.

Early life socioeconomic adversity is associated in adult life with chronic inflammation, carotid atherosclerosis, poorer lung function and decreased cognitive performance: a cross-sectional, population-based study

BACKGROUND

Socioeconomic gradients in health persist despite public health campaigns and improvements in healthcare. The Psychosocial and Biological Determinants of Ill-health (pSoBid) study was designed to uncover novel biomarkers of chronic disease that may help explain pathways between socioeconomic adversity and poorer physical and mental health.

METHODS

We examined links between indicators of early life adversity, possible intermediary phenotypes, and markers of ill health in adult subjects (n = 666) recruited from affluent and deprived areas. Classical and novel risk factors for chronic disease (lung function and atherosclerosis) and for cognitive performance were assessed, and associations sought with early life variables including conditions in the parental home, family size and leg length.

RESULTS

Associations were observed between father's occupation, childhood home status (owner-occupier; overcrowding) and biomarkers of chronic inflammation and endothelial activation in adults (C reactive protein, interleukin 6, intercellular adhesion molecule; P < 0.0001) but not number of siblings and leg length. Lung function (forced expiratory volume in 1 second) and cognition (Choice Reaction Time, the Stroop test, Auditory Verbal Learning Test) were likewise related to early life conditions (P < 0.001). In multivariate models inclusion of inflammatory variables reduced the impact and independence of early life conditions on lung function and measures of cognitive ability. Including variables of adult socioeconomic status attenuated the early life associations with disease biomarkers.

CONCLUSIONS

Adverse levels of biomarkers of ill health in adults appear to be influenced by father's occupation and childhood home conditions. Chronic inflammation and endothelial activation may in part act as intermediary phenotypes in this complex relationship. Reducing the 'health divide' requires that these life course determinants are taken into account.