Serum high sensitivity C-reactive protein and cognitive function in elderly women

Cognitive impairment among elderly individuals in Shanghai suburb, China: association of C-reactive protein and its interactions with other relevant factors

OBJECTIVES

To investigate the association between serum C-reactive protein (CRP) concentration and cognitive impairment as well as interactions between CRP and other relevant factors.

METHODS

Patients with cognitive impairment and 1 to 2 age- and sex-matched controls nested from a population-based study among residents aged 60 years and older in Shanghai suburb. The associations of serum CRP concentration and other relevant factors were examined with logistic regression analysis.

RESULTS

The mean CRP in patients with cognitive impairment was higher than that in controls (P < .001). The highest quartile of CRP (>4.77 mg/L), abdomen obesity, hypertriglyceridemia, and hyperglycemia was associated with cognitive impairment. Significant interactions were found between increased CRP and hypertriglyceridemia as well as between increased CRP and hyperglycemia on cognitive impairment; and the attributable proportion due to interaction was 82% (P < .0001) and 37% (P = .007), respectively.

CONCLUSIONS

Increased CRP was associated with cognitive impairment, and additive effects of increased CRP with hypertriglyceridemia and hyperglycemia on cognitive impairment were observed among elderly individuals.

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.

Assessment of plasma C-reactive protein as a biomarker of posttraumatic stress disorder risk

IMPORTANCE

Posttraumatic stress disorder (PTSD) has been associated in cross-sectional studies with peripheral inflammation. It is not known whether this observed association is the result of PTSD predisposing to inflammation (as sometimes postulated) or to inflammation predisposing to PTSD.

OBJECTIVE

To determine whether plasma concentration of the inflammatory marker C-reactive protein (CRP) helps predict PTSD symptoms.

DESIGN, SETTING, AND PARTICIPANTS

The Marine Resiliency Study, a prospective study of approximately 2600 war zone-deployed Marines, evaluated PTSD symptoms and various physiological and psychological parameters before deployment and at approximately 3 and 6 months following a 7-month deployment. Participants were recruited from 4 all-male infantry battalions imminently deploying to a war zone. Participation was requested of 2978 individuals; 2610 people (87.6%) consented and 2555 (85.8%) were included in the present analysis. Postdeployment data on combat-related trauma were included for 2208 participants (86.4% of the 2555 included) and on PTSD symptoms at 3 and 6 months after deployment for 1861 (72.8%) and 1617 (63.3%) participants, respectively.

MAIN OUTCOMES AND MEASURES

Severity of PTSD symptoms 3 months after deployment assessed by the Clinician-Administered PTSD Scale (CAPS).

RESULTS

We determined the effects of baseline plasma CRP concentration on postdeployment CAPS using zero-inflated negative binomial regression (ZINBR), a procedure designed for distributions, such as CAPS in this study, that have an excess of zeroes in addition to being positively skewed. Adjusting for the baseline CAPS score, trauma exposure, and other relevant covariates, we found baseline plasma CRP concentration to be a highly significant overall predictor of postdeployment CAPS scores (P = .002): each 10-fold increment in CRP concentration was associated with an odds ratio of nonzero outcome (presence vs absence of any PTSD symptoms) of 1.51 (95% CI, 1.15-1.97; P = .003) and a fold increase in outcome with a nonzero value (extent of symptoms when present) of 1.06 (95% CI, 0.99-1.14; P = .09).

CONCLUSIONS

AND RELEVANCE A marker of peripheral inflammation, plasma CRP may be prospectively associated with PTSD symptom emergence, suggesting that inflammation may predispose to PTSD.

C-reactive protein and cognition are unrelated to leukoaraiosis

Elevated serum levels of C-reactive protein (CRP) have been associated with leukoaraiosis in elderly brain. However, several studies indicate that leukoaraiosis is associated with an increased risk of cognitive impairment. It is unknown how the effect of CRP on cognition is mediated by leukoaraiosis. The purpose of this study is to assess the relationship between serum levels of CRP, the presence of leukoaraiosis, and cognitive impairment in a population of coronary patients over 50 years old. CRP levels explained 7.18% (P: 0.002) of the variance of the MMSE. The adjustment for the presence of leukoaraiosis little changed this variance (5.98%, P: 0.005), indicating that only a small portion of the CRP influence on cognition was mediated via leukoaraiosis. Patients with CRP levels ≥5.0 had 2.9 (95% CI: 1.26–6.44) times more chance to present cognitive impairment (P: 0.012). We found that elevated serum levels of CRP were associated with increased risk of cognitive impairment in elderly and it was not mediated by presence of leukoaraiosis.

Abdominal obesity is associated with peripheral artery disease in hemodialysis patients

Background

Peripheral arterial disease (PAD) is a leading cause of morbidity in hemodialysis (HD) patients. Recent evidence suggests that abdominal obesity (AO) may play a role in PAD. However, the association between AO and PAD has not been thoroughly studied in HD patients.

Methods

The present cross-sectional study aimed to examine the relationship between AO and PAD in a cohort of 204 chronic HD patients. The ankle brachial index (ABI) was used as an estimate of the presence of PAD. Plasma adiponectin levels, interleukin-6 (IL-6) levels, high sensitivity C-reactive protein (hs-CRP) levels, asymmetric dimethylarginine (ADMA) levels, and lipid profiles were measured. Logistic regression was used to estimate the association between the presence of PAD and AO as well as other potential risk factors.

Results

The metabolic risk factors and all individual traits, including elevated ln-transformed hs-CRP, were found to be significant (P<0.05) more frequently in HD patients with AO than that in control subjects. Patients with AO had a higher prevalence of PAD than the control individuals, with a mean ABI of 0.96±0.23 and 1.08±0.16 (P<0.0001) and PAD prevalence of 26.9% and 10.8% (P = 0.003), respectively. By multivariate analysis, AO (odds ratio [OR], 4.532; 95% CI, 1.765–11.639; P = 0.002), elevated serum ln-transformed ADMA (OR, 5.535; 95% CI, 1.323–23.155; P = 0.019), and ln-transformed IL-6 (OR, 1.567; 95% CI, 1.033–2.378; P = 0.035) were independent predictors of the presence of PAD.

Conclusions

HD patients with AO exhibited a cluster of metabolic risk factors and lower ABI. AO, elevated serum ln-transformed ADMA, and ln-transformed IL-6 were independent predictors of the presence of PAD.

Inflammation and clinical presentation in neurodegenerative disease: a volatile relationship

A proposed immune mechanism that potentially modifies or exacerbates neurodegenerative disease presentation in older adults has received considerable attention in the past decade, with recent studies demonstrating a strong link between pro-inflammatory markers and neurodegeneration. The overarching aim of the following review is to synthesize recent research that supports a possible relationship between inflammation and clinical features of neurodegenerative diseases, including risk of development, cognitive and clinical correlates, and progression of the specified diseases. Specific emphasis is placed on providing a temporal context for the association between inflammation and neurodegeneration.

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.

The Relation between Inflammation and Neuropsychological Test Performance

Background. Considerable research documents an association between pro- and anti-inflammatory markers and Alzheimer's disease (AD), yet the differential relation between these markers and neuropsychological functioning in AD and nondemented controls has received less attention. The current study sought to evaluate the relationship between peripheral markers of inflammation (both pro- and anti-inflammatory) and neuropsychological functioning through the Texas Alzheimer's Research and Care Consortium (TARCC) cohort. Methods. There were 320 participants (Probable AD n = 124, Controls n = 196) in the TARCC Longitudinal Research Cohort available for analysis. Regression analyses were utilized to examine the relation between proinflammatory and anti-inflammatory markers and neuropsychological functioning. Follow-up analyses were conducted separately by case versus control status. Results. Proinflammatory and anti-inflammatory markers were found to be associated with neuropsychological testing. Third tertile proinflammatory markers were negatively associated with measures of attention and language, and anti-inflammatory markers were positively associated with measures of immediate verbal memory and delayed verbal and visual memory. Conclusions. These findings support the link between peripheral inflammatory markers and neuropsychological functioning and suggest the utility of examining profiles of inflammatory markers in the future.

Association between C-reactive protein and cognitive deficits in elderly men and women: a meta-analysis

BACKGROUND

Certain risk factors for cognitive decline appear modifiable. A potentially modifiable marker of inflammation, C-reactive protein may be associated with cognitive deficits, although not all studies have found a relationship between C-reactive protein and cognitive ability. Further, few research papers have examined whether gender may affect any association between C-reactive protein and cognitive deficit.

METHODS

To better understand the association between C-reactive protein, cognitive deficit, and gender in elderly people, we meta-analyzed cross-sectional studies that reported cognitive ability assessed by the Mini-Mental State Examination or an equivalent measure, C-reactive protein concentrations, and gender.

RESULTS

While we identified no studies containing only male subjects, the two identified studies containing both female and male subjects (n = 2,525) showed an effect size for cognition of -0.1809 (95% confidence interval, -0.2652 to -0.0967, p = 0.000025) between high and low C-reactive-protein groups. In contrast, the two identified studies containing only female subjects (n = 1,754) showed an effect size for cognition of 0.0345 (95% confidence interval, -0.0594 to 0.1285, not significant).

CONCLUSIONS

In the context of a small number of source studies and lack of an all-male group, these results suggest that any association between C-reactive protein and cognitive deficits may be stronger in elderly men than in elderly women.

Variety in fruit and vegetable intake and cognitive function in middle-aged and older Puerto Rican adults

Higher variety in fruit and vegetable intake has been associated with a lower risk of several chronic diseases. It remains unclear whether such associations exist relating to cognition. The authors examined associations between total quantity and variety in fruit and vegetable intake and cognitive function in a cross-sectional sample of 1412 Puerto Rican adults, aged 45-75 years from the Boston Puerto Rican Health Study, 2004-9. Fruit and vegetable intake was assessed with a FFQ. Cognitive function was measured with a battery of seven tests; the Mini Mental State Examination (MMSE) was administrated to assess global cognitive function. Greater variety, but not total quantity, of fruit and vegetable intake was associated with a higher MMSE score after multivariate adjustment (P for trend = 0·012). This association remained significant after further adjusting for total quantity of fruit and vegetable intake (P for trend = 0·018). High variety of fruit and vegetable intake was also associated with individual cognitive domains, including executive function, memory and attention (all P for trend < 0·05). Variety, more than total quantity, of fruit and vegetable intake may offer cognitive protection in middle-aged and older adults, but longitudinal studies are needed to clarify direction of causality.

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.

White blood cell count and psychomotor cognitive performance in the elderly

BACKGROUND

White blood cell (WBC) count is associated with many inflammatory diseases such as cardiovascular disease, diabetes and hypertension. Research on the relationship of WBC count and cognition in the elderly is relatively sparse. This study examined the association between WBC count and cognitive performance in older adults.

METHODS

Data from the National Health and Nutrition Examination Survey (1999-2002) containing 1670 older adults were analysed. Every subject completed a household interview, examination of digit symbol substitution test (DSST) scores, WBC count measurement and a questionnaire regarding personal health. WBC count was restricted to the normal range and divided into quartiles, using a multiple hierarchical regression model to estimate the relationship between WBC counts and DSST scores. Quartile-based analysis with an extended-model approach was used for further covariates adjustment. Trends test examining the associations across increasing quartiles of WBC counts and DSST scores were also conducted.

RESULTS

In the multiple hierarchical regression model, the β coefficient, representing the change of DSST scores for each 1000 cells uL(-1) increase in WBC count, was -0·097 (R(2) = 0·343, P < 0·001). After additional competent covariates adjustment, the negative correlation remained (all P < 0·001). In quartile-based multiple linear regression, the negative trends between DSST scores and WBC count quartiles in the stratified comparison with extended-model approach were all statistically significant (P for trends <0·001).

CONCLUSIONS

Higher WBC counts, even within the normal range, were associated with poor psychomotor cognitive performance in the elderly.

Association of C-reactive protein with mild cognitive impairment

BACKGROUND

Inflammation is proposed to play a role in the development of Alzheimer's disease, and may also be involved in the pathogenesis of mild cognitive impairment (MCI). This study examined the association of inflammatory markers in serum or plasma with prevalent MCI and MCI subtypes in a population-based sample.

METHODS

Olmsted County, MN, residents aged 70-89 years on October 1, 2004, were evaluated using the Clinical Dementia Rating Scale, a neurological evaluation, and neuropsychological testing. Information ascertained for each participant was reviewed by an expert panel of neuropsychologists, physicians, and nurses, and a diagnosis of normal cognition, MCI, or dementia was made by consensus. C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis alpha (TNFalpha), and adiponectin were measured at baseline.

RESULTS

Among 313 subjects with MCI and 1570 cognitively normal subjects, a CRP level in the upper quartile (>3.3 mg/L) was significantly associated with MCI (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.00-2.01) and with nonamnestic MCI (OR, 2.05; 95% CI, 1.12-3.78) after adjusting for age, sex, and years of education. However, there was no association with amnestic MCI (OR, 1.21; 95% CI, 0.81-1.82). No association was observed with the other inflammatory markers.

CONCLUSIONS

Plasma CRP is associated with prevalent MCI and with nonamnestic MCI in elderly, nondemented persons in a population-based setting. These findings suggest the involvement of inflammation in the pathogenesis of MCI.

Reverse causation in the association between C-reactive protein and fibrinogen levels and cognitive abilities in an aging sample

OBJECTIVE

To test the hypothesis that increased levels of inflammatory and hemostatic markers are associated with poorer cognitive performance and to assess the influence of childhood intelligence quotient (IQ) and current cardiovascular disease (CVD) risk factors on this relationship. Blood inflammatory markers have been shown to predict late-life cognition, although the mechanism through which this occurs is unknown.

METHODS

Levels of the biomarkers C-reactive protein and fibrinogen were measured in 1053 Scottish participants (50.2% female) from the Lothian Birth Cohort 1936 ranging in age from 67 to 71 years. Biomarker levels were tested for their association with diverse cognitive abilities.

RESULTS

Significant cross-sectional associations were found between the biomarkers and various cognitive abilities: their effect size was around 1% of the variance and was in the direction of higher marker levels conferring poorer cognitive performance. With the exception of the reaction time measures (and fibrinogen), these associations could be explained by childhood IQ, CVD risk factors, or both. Importantly, both the inflammatory markers at age 70 years were associated (p < .001) with childhood IQ.

CONCLUSIONS

Whereas inflammatory marker levels predict contemporaneous general cognitive ability, the results support a model of reverse causation because childhood IQ predicts late-life inflammation. This might be through its association with later life CVD risk factors or because it is a measure of system integrity. Unlike general cognitive ability, the association between inflammatory markers (particularly fibrinogen) and processing speed was maintained in the presence of childhood IQ and/or CVD risk factor adjustments. This might also reflect variation in physiological integrity.

Associations of depression with C-reactive protein, IL-1, and IL-6: a meta-analysis

OBJECTIVE

To assess the magnitude and direction of associations of depression with C-reactive protein (CRP), interleukin (IL)-1, and IL-6 in community and clinical samples.

METHODS

Systematic review of articles published between January 1967 and January 2008 in the PubMed and PsycINFO electronic databases was performed. Effect sizes were calculated as stat d and meta-analyzed, using random-effects models.

RESULTS

Each inflammatory marker was positively associated with depression; CRP, d = 0.15 (95% CI = 0.10, 0.21), p < .001; IL-6, d = 0.25 (95% CI = 0.18, 0.31), p < .001; IL-1, d = 0.35 (95% CI = 0.03, 0.67), p = .03; IL-1ra, d = 0.25 (95% CI = 0.04, 0.46), p = .02. Associations were strongest in clinically depressed patient samples--but were also significant in community-based samples--and when clinical interviews were used. Studies adjusting for body mass index (BMI) had smaller associations, albeit significant. Relationships were inconsistent with respect to age, medication, and sex. Depression was related to CRP and IL-6 among patients with cardiac disease or cancer.

CONCLUSIONS

Depression and CRP, IL-1, and IL-6 are positively associated in clinical and community samples and BMI is implicated as a mediating/moderating factor. Continuity in clinic- and community-based samples suggests there is a dose-response relationship between depression and these inflammatory markers, lending strength to the contention that the cardiac (or cancer) risk conferred by depression is not exclusive to patient populations. Available evidence is consistent with three causal pathways: depression to inflammation, inflammation to depression, and bidirectional relationships.