Serum uric acid and impaired cognitive function in a cohort of healthy young elderly: data from the Brisighella Study

Role of uric acid in neurodegenerative diseases, focusing on Alzheimer and Parkinson disease: A new perspective

Neurodegenerative diseases (NDs) such as Alzheimer disease (AD) and Parkinson disease (PD) are group of diseases affecting the central nervous system (CNS) characterized by progressive neurodegenerations and cognitive impairment. Findings from different studies highlighted the beneficial and detrimental effects of serum uric acid on the development and progression of NDs. Therefore, this mini-review aims to discuss the beneficial and detrimental effects of uric on NDs. The neuroprotective effect of uric acid is mainly related to the antioxidant effect of uric acid which alleviates oxidative stress-induced neurodegeneration in AD and PD. However, long-term effect of hyperuricemia prompts for the development and progression of cognitive impairment. Hyperuricemia is associated with cognitive impairment and dementia, and gout increases dementia risk. In addition, hyperuricemia can cause cerebral vascular injury which is a risk factor for vascular dementia and cognitive impairment. Taken together, the relationship between uric acid and NDs risk remains conflicting. Hence, preclinical and clinical studies are indicated in this regard.

Higher serum uric acid is associated with poorer cognitive performance in healthy middle-aged people: a cross-sectional study

Age-related cognitive impairment can occur many years before the onset of the clinical symptoms of dementia. Uric acid (UA), a metabolite of purine-rich foods, has been shown to be positively associated with improved cognitive function, but such association remains controversial. Moreover, most of the previous studies investigating the association included elderly participants with memory-related diseases. Therefore, the present study aimed at investigating whether serum UA (sUA) is associated with cognitive performance in healthy middle-aged individuals. We conducted a cross-sectional study on a cohort of middle-aged individuals (40-60 years old) who participated in the Qatar Biobank. The participants had no memory-related diseases, schizophrenia, stroke, or brain damage. They were divided according to sUA level into a normal group (< 360 μmol/L) and a high group (≥ 360 μmol/L), and underwent an assessment of cognitive function using the Cambridge Neuropsychological Test Automated Battery. Two cognitive function domains were assessed: (a) speed of reaction/reaction time and (b) short-term visual memory. The median age of the 931 participants included in the study was 48.0 years (IQR: 44.0, 53.0), of which 47.6% were male. Adjusted multivariable linear regression analyses showed that higher sUA is associated with poorer performance on the visual memory domain of cognitive function (β = - 6.87, 95% CI - 11.65 to - 2.10, P = 0.005), but not on the speed of reaction domain (β = - 55.16, 95% CI - 190.63 to 80.30, P = 0.424). Our findings support previous studies suggesting an inverse association between high sUA levels and cognitive function in elderly and extend the evidence for such a role to middle-aged participants. Further prospective studies are warranted to investigate the relationship between UA and cognition.

Moderating effects of uric acid and sex on cognition and psychiatric symptoms in asymmetric Parkinson's disease

BACKGROUND

Non-motor symptoms are an important early feature of Parkinson's disease (PD), encompassing a variety of cognitive and psychiatric symptoms that seem to manifest differently depending on motor symptom asymmetry. Different factors, such as uric acid (UA) and sex, seem to influence cognitive and psychiatric expression in PD, however their interplay remains to be better understood.

METHODS

Participants taking part in the Parkinson's Progression Marker Initiative were studied based on the side of motor symptom asymmetry and sex. Three-way interaction modeling was used to examine the moderating effects of sex and UA on cognitive functions and psychiatric symptoms.

RESULTS

Significant three-way interactions were highlighted at 1-year follow-up between motor symptom asymmetry, UA and sex for immediate and long-term memory in female patients exhibiting predominantly left-sided motor symptoms, and for processing speed and sleepiness in female patients exhibiting predominantly right-sided motor symptoms. No significant interactions were observed for male patients. Moreover, female patients exhibiting predominantly right-sided motor symptoms demonstrated lower serum UA concentrations and had overall better outcomes, while male patients with predominantly right-sided motor symptoms demonstrated particularly poor outcomes.

CONCLUSIONS

These findings suggest that in the earliest stages of the disease, UA and sex moderate cognitive functions and psychiatric symptoms differently depending on motor asymmetry, holding important clinical implications for symptom management in patients.

Longitudinal follow-up study of the association with gout and Alzheimer's disease and Parkinson's disease in Korea

To date, no clear conclusion on the relationships of gout with the occurrence of typical neurodegenerative diseases, Alzheimer's disease (AD) and Parkinson's disease (PD), has been reached. This study aimed to determine whether the patients with gout are at a lower or higher probability of developing AD or PD than those without gout. Longitudinal follow-up data of a representative sample of Korean adults were assessed. 18,079 individuals diagnosed with gout between 2003 and 2015 were enrolled in the gout group. The comparison group comprised 72,316 demographics-matched individuals not diagnosed with gout. Longitudinal associations of gout with AD or PD were estimated using Cox proportional hazard regression adjusting for potential confounders. The adjusted hazard ratios (HRs) of AD and PD in the gout group were 1.01 and 1.16 times higher than controls, but these differences were not statistically significant (95% confidence interval [CI] = 0.92-1.12 and 95% CI = 0.97-1.38, respectively). Although there was no significant association in the entire sample, AD and PD probabilities in patients with gout were significantly higher in participants < 60 years, and PD probabilities in patients with gout were significantly higher in overweight participants. Our findings identify significant correlations of gout with AD and PD in participants < 60 years and gout with PD in those with overweight, indicating that gout may play a role in the development of neurodegenerative diseases in younger or overweight populations. Further investigations should be performed to corroborate these findings.

The Association of Serum Uric Acid Level, Gout, and Alzheimer's Disease: A Bidirectional Mendelian Randomization Study

BACKGROUND

The relationship between serum uric acid (UA) and Alzheimer's disease (AD) risk still remained ambiguous despite extensive attempts.

OBJECTIVE

Via the two-sample Mendelian randomization (MR) design, we aimed to examine the bidirectional causal relationships of serum UA, gout, and the risk of AD.

METHODS

Genetic variants of UA, gout, and AD were extracted from published genome-wide association summary statistics. The inverse-variance weighted (IVW, the primary method), and several sensitivity methods (MR-Egger, weighted median, and weighted mode) were used to calculate the effect estimates. Egger regression, MR-PRESSO and leave-one-SNP-out analysis were performed to identify potential violations.

RESULTS

Genetic proxies for serum UA concentration [odds ratio (ORIVW) = 1.09, 95% confidence interval (CI) = 1.01-1.19, p = 0.031] were related with an increased risk of AD using 25 single nucleotide polymorphisms (SNPs). This causal effect was confirmed by sensitivity analyses including MR-Egger (1.22, 1.06-1.42, p = 0.014), weighted median (1.18, 1.05-1.33, p = 0.006), and weighted mode (1.20, 1.07-1.35, p = 0.005) methods. No evidence of notable directional pleiotropy and heterogeneity were identified (p >  0.05). Three SNPs (rs2078267, rs2231142, and rs11722228) significantly drove the observed causal effects. Supportive causal effect of genetically determined gout on AD risk was demonstrated using two SNPs (ORIVW = 1.05, 95% CI = 1.00-1.11, p = 0.057). No reverse causal effects of AD on serum UA levels and gout risk were found.

CONCLUSION

The findings revealed a causal relationship between elevated serum UA level and AD risk. However, further research is still warranted to investigate whether serum UA could be a reliable biomarker and therapeutic target for AD.

Potential Value of Serum Uric Acid in the Identification of Postoperative Delirium in Geriatric Patients Undergoing Knee Replacement

Objectives

The relationship between preoperative serum uric acid (SUA) and cerebrospinal fluid (CSF) Alzheimer-related biomarkers were investigated to determine whether high SUA is a potential risk factor for postoperative delirium (POD) and to evaluate its predictive efficacy.

Methods

The participants were selected from the Perioperative Neurocognitive Disorder Risk Factor and Prognosis (PNDRFAP) study and the Perioperative Neurocognitive Disorder and Biomarker Lifestyle (PNDABLE) study. The logistic regression equation was used to analyze the risk factors and protective factors of POD. The interaction term (SUA × Sex) was introduced into the linear model to explore the potential modification effects of sex on the identified correlations. We analyzed the mediating effects of Alzheimer-related biomarkers. Finally, we constructed the receiver operating characteristic (ROC) curve and the nomogram model to evaluate the efficacy of SUA and Alzheimer-related biomarkers in predicting POD.

Results

Patients with POD had elevated SUA level (PNDRFAP: p = 0.002, PNDABLE: p < 0.001). Preoperative SUA level was positively correlated with CSF phosphorylated tau (P-tau) (p = 0.027) and β-amyloid42 (Aβ₄₂)/P-tau (p = 0.023). Interaction analysis did not find any modification effect of sex. The relationship between SUA and POD was partially mediated by CSF P-tau (15.3%). ROC curve showed that the model combining SUA and Alzheimer-related biomarkers had better performance in predicting POD [area under the curve (AUC) = 0.880; p < 0.001], and the predictive model is accurate.

Conclusions

High SUA may enhance CSF P-tau level, thus increasing the risk of POD, and the model combining SUA and Alzheimer-related biomarkers can accurately predict the occurrence of POD.

Oxidative Stress Mediates the Association Between Dietary Fat Intake and Cognition in US Older Adults

OBJECTIVE

Dietary fat intake was considered as a modifiable factor influencing cognitive performance. The objective was to 1) examine the associations between different types of dietary fat intakes and cognitive outcomes among elder adults (≥60 years old); 2) assess whether peripheral oxidative stress and antioxidant biomarkers are potential mediators of dietary fat intake and cognitive impairment relationship.

METHODS

Using data from National Health and Nutrition Examination Survey 2011-2014, total fat, saturated fatty acid (SFAT), monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), cholesterol, ω-3 and ω-6 fatty acids were used to evaluate dietary fat intakes. Cognitive outcomes were assessed by word learning and recall modules from the consortium to establish a registry for Alzheimer's Disease (CERAD), animal fluency test, and digit symbol substitution test (DSST). Antioxidant biomarkers were assessed by gamma glutamyl transpeptidase (GGT), bilirubin, uric acid, and vitamin D levels. Linear regression models and causal mediation analysis were applied to quantify the associations.

RESULTS

A total of 2,253 elder adults were included in the data analyses. Dietary intake of PUFA and ω-6 fatty acid were positively associated with DSST [β (95% CI): 0.06 (0.01,0.10), t statistic = 2.39, df= 2238, p = 0.02; β (95% CI): 0.06 (0.01,0.11), t statistic = 2.54, df= 2238, p = 0.01, respectively]. GGT was negatively associated with DSST [β (95% CI): -0.04 (-0.07, -0.01), t statistic = -2.73, df= 2239, p = 0.01], whereas uric acid was positively associated with CERAD total score [β (95% CI): 0.04 (0.00,0.08), t statistic = 2.03, df= 2233, p = 0.04]. The association between dietary intake of PUFA/ω -3/ω -6 and DSST performance was partially mediated by GGT level.

CONCLUSION

Our findings support that PUFAs in dietary sources were associated with lower risks for cognitive impairment partially via lowering oxidative stress. Dietary PUFA supplementation may potentially reduce risk of cognitive impairment via antioxidative mechanism.

Cognitive Impairment in End Stage Renal Disease Patients Undergoing Hemodialysis: Markers and Risk Factors

(1) Background: Cognitive impairment (CI) is common in chronic kidney disease (CKD) and patients treated with hemodialysis. (2) Methods: The systematic review was prepared following the PRISMA statement (2013). The biomedical electronic databases MEDLINE and SCOPUS were searched. (3) Results: out of 1093 studies, only 30, which met problem and population criteria, were included in this review. The risk factors for CI can be divided into three groups: traditional risk factors (present in the general population), factors related to dialysis sessions, and nontraditional risk factors occurring more frequently in the HD group. (4) Conclusions: the methods of counteracting CI effective in the general population should also be effective in HD patients. However, there is a need to develop unique anti-CI approaches targeting specific HD risk factors, i.e., modified hemodialysis parameters stabilizing cerebral saturation and blood flow.

The Influence of Serum Uric Acid on the Brain and Cognitive Dysfunction

Uric acid is commonly known for its bad reputation. However, it has been shown that uric acid may be actively involved in neurotoxicity and/or neuroprotection. These effects could be caused by oxidative stress or inflammatory processes localized in the central nervous system, but also by other somatic diseases or systemic conditions. Our interest was to summarize and link the current data on the possible role of uric acid in cognitive functioning. We also focused on the two putative molecular mechanisms related to the pathological effects of uric acid-oxidative stress and inflammatory processes. The hippocampus is a prominent anatomic localization included in expressing uric acid's potential impact on cognitive functioning. In neurodegenerative and mental disorders, uric acid could be involved in a variety of ways in etiopathogenesis and clinical presentation. Hyperuricemia is non-specifically observed more frequently in the general population and after various somatic illnesses. There is increasing evidence to support the hypothesis that hyperuricemia may be beneficial for cognitive functioning because of its antioxidant effects but may also be a potential risk factor for cognitive dysfunction, in part because of increased inflammatory activity. In this context, gender specificities must also be considered.

High Blood Uric Acid Is Associated With Reduced Risks of Mild Cognitive Impairment Among Older Adults in China: A 9-Year Prospective Cohort Study

Background: It remains unsolved that whether blood uric acid (UA) is a neuroprotective or neurotoxic agent. This study aimed to evaluate the longitudinal association of blood UA with mild cognitive impairment (MCI) among older adults in China.

Methods: A total of 3,103 older adults (aged 65+ years) free of MCI at baseline were included from the Healthy Aging and Biomarkers Cohort Study (HABCS). Blood UA level was determined by the uricase colorimetry assay and analyzed as both continuous and categorical (by quartile) variables. Global cognition was assessed using the Mini-Mental State Examination four times between 2008 and 2017, with a score below 24 being considered as MCI. Cox proportional hazards models were used to examine the associations.

Results: During a 9-year follow-up, 486 (15.7%) participants developed MCI. After adjustment for all covariates, higher UA had a dose-response association with a lower risk of MCI (all P_{for  trend} < 0.05). Participants in the highest UA quartile group had a reduced risk [hazard ratio (HR), 0.73; 95% (CI): 0.55–0.96] of MCI, compared with those in the lowest quartile group. The associations were still robust even when considering death as a competing risk. Subgroup analyses revealed that these associations were statistically significant in younger older adults (65–79 years) and those without hyperuricemia. Similar significant associations were observed when treating UA as a continuous variable.

Conclusions: High blood UA level is associated with reduced risks of MCI among Chinese older adults, highlighting the potential of managing UA in daily life for maintaining late-life cognition.

The Influence of Serum Uric Acid Level on Alzheimer's Disease: A Narrative Review

As a powerful antioxidant in the human body, uric acid (UA) has been the subject of increasing research that focused on its influence on Alzheimer's disease (AD) in recent years. The latest literature was gathered to describe the influence of serum uric acid (SUA) level on the onset and progression of AD and to analyze the possibility that SUA is a biomarker of Alzheimer's disease. A large number of existing studies suggested that the SUA level was lower or tended to decrease in patients with AD, and increased SUA level may have a protective effect in AD, which could reduce the risk of onset and slowing the course of the disease. However, some Mendelian randomization analyses suggested that genetically determined uric acid was not associated with AD risk. Existing research results are contradictory due to the high inconsistency of the studies, the selection of subjects, and other factors. UA also showed a strong association with cognitive function, and there appeared to be a gender-selective neuroprotective action. Due to its potent antioxidant properties, the low uric acid level may contribute to oxidative stress to accelerate disease progression. But some preclinical data showed a possibility that in some special cases, UA had a prooxidant properties. The possibility was raised in the discussion of the underlying mechanism that both the low uric acid level and the rapidly progressive course of the disease were the consequence of malnutrition. This paper reviews recent advances in the study of SUA and AD which offers the possibility of new biomarker, new prevention, and treatment strategies for Alzheimer's disease.

Serum Uric Acid May Aggravate Alzheimer's Disease Risk by Affecting Amyloidosis in Cognitively Intact Older Adults: The CABLE Study

BACKGROUND

Serum uric acid (SUA) affects the reaction of oxidative stress and free radicals in the neurodegenerative processes. However, whether SUA impacts Alzheimer's disease (AD) pathology remains unclear.

OBJECTIVE

We aimed to explore whether high SUA levels can aggravate the neurobiological changes of AD in preclinical AD.

METHODS

We analyzed cognitively intact participants (n = 839, age 62.16 years) who received SUA and cerebrospinal fluid (CSF) biomarkers (amyloid-β [Aβ], total tau [t-Tau], and phosphorylated tau [p-Tau]) measurements from the Chinese Alzheimer's Biomarker and LifestylE (CABLE) database using multivariable-adjusted linear models.

RESULTS

Levels of SUA in the preclinical AD elevated compared with the healthy controls (p = 0.007) and subjects with amyloid pathology had higher concentration of SUA than controls (p = 0.017). Roughly, equivalent levels of SUA displayed among cognitively intact individuals with or without tau pathology and neurodegeneration. CSF Aβ1 - 42 (p = 0.019) and Aβ1 - 42/Aβ1 - 40 (p = 0.027) were decreased and CSF p-Tau/Aβ1 - 42 (p = 0.009) and t-Tau/Aβ1 - 42 (p = 0.043) were increased with the highest (> 75th percentile) SUA when compared to lowest SUA, implying a high burden of cerebral amyloidosis in individuals with high SUA. Sensitivity analyses using the usual threshold to define hyperuricemia and precluding drug effects yielded robust associations. Nevertheless, the quadratic model did not show any U-shaped relationships between them.

CONCLUSION

SUA may aggravate brain amyloid deposition in preclinical AD, which corroborated the detrimental role of SUA.

The relationship between serum uric acid and cognitive function in patients with chronic heart failure

BACKGROUND

Evidence has shown that serum uric acid (UA) is associated with cognitive function, but this finding remains debatable. Serum UA is commonly elevated in patients with chronic heart failure (CHF), especially in men. However, the relationship between serum UA and cognitive function in CHF populations and stratified by sex are unclear. We aimed to examine whether serum UA was independently associated with cognitive function in CHF populations after controlling for demographic, medical and psychological variables and whether there was a sex difference in the association between serum UA and cognitive function among male and female CHF patients.

METHODS

One hundred ninety-two hospitalized patients with CHF underwent an assessment of cognitive function using the Montreal Cognitive Assessment (MoCA) and the determination of serum UA. Hyperuricemia was defined as serum UA ≥7 mg/dl in men and ≥ 6 mg/dl in women. Multiple linear hierarchical regression analyses were conducted to examine the independent association between serum UA and cognitive function in CHF populations and stratified by sex.

RESULTS

The mean serum UA concentration of participants was 7.3 ± 2.6 mg/dL. The prevalence of hyperuricemia was 54.7% (105 of 192) in CHF patients, 52.9% (64 of 121) in men, and 57.7% (41 of 71) in women. In the total sample, higher serum UA was associated with poorer cognitive function independent of demographic, medical and psychological variables (β = - 0.130, ΔR² = 0.014, p = 0.015). In sex-stratified groups, elevated serum UA was independently associated with worse cognitive function in men (β = - 0.247, ΔR² = 0.049, p = 0.001) but not in women (β = - 0.005, ΔR² = 0.000, p = 0.955).

CONCLUSIONS

Higher serum UA is independently associated with poorer cognitive function in CHF populations after adjusting for confounding variables. Furthermore, elevated serum UA is independently related to worse performance on cognitive function in men but not in women. More longitudinal studies are needed to examine the association between serum UA and cognitive function in CHF populations and stratified by sex.

Associations of serum uric acid with incident dementia and cognitive decline in the ARIC-NCS cohort

INTRODUCTION

Elevated serum uric acid (SUA) is associated with cardiovascular risk factors, which often contribute to dementia and dementia-like morbidity, yet several cross-sectional studies have shown protective associations with cognition, which would be consistent with other work showing benefits of elevated SUA through its antioxidant properties.

METHODS

We studied 11,169 participants free of dementia and cardiovascular disease from the Atherosclerosis Risk in Communities (ARIC) cohort. SUA was measured in blood samples collected in 1990-92, baseline for this study (age range 47-70 years). Incident dementia was ascertained based on clinical assessments in 2011-13 and 2016-17, surveillance based on dementia screeners conducted over telephone interviews, hospitalization discharge codes, and death certificates. Cognitive function was assessed up to four times between 1990 and 92 and 2016-17. We estimated the association of SUA, categorized into quartiles, with incidence of dementia using Cox regression models adjusting for potential confounders. The association between cognitive decline and SUA was assessed using generalized estimating equations.

RESULTS

Over a median follow-up period of 24.1 years, 2005 cases of dementia were identified. High baseline SUA was associated with incident dementia (HR, 1.29; 95% CI, 1.12, 1.47) when adjusted for sociodemographic variables. However, after further adjustment including cardiovascular risk factors, this relationship disappeared (HR, 1.03; 95% CI, 0.88, 1.21). Elevated baseline SUA was associated with faster cognitive decline even after further adjustment (25-year global z-score difference, -0.149; 95% CI, -0.246, -0.052).

CONCLUSION

Higher levels of mid-life SUA were associated with faster cognitive decline, but not necessarily with higher risk of dementia.

Diurnal blood pressure loads are associated with lower cognitive performances in controlled-hypertensive elderly individuals

INTRODUCTION

Hypertension in midlife adults is associated with cognitive decline later in life. In individuals treated for hypertension, blood pressure (BP) loads have been associated with end organ damages. This study examines whether BP load inversely correlates with performance in cognitive tasks in normotensive or controlled hypertensive (CHT) individuals.

METHODS

Participants between 60 and 75 years old were divided into normotensive participants who did not receive antihypertensive treatment (n = 49) and CHT patients (n = 28). They were evaluated for BP using ambulatory blood pressure monitoring and cognitive functions with tests assessing cognitive flexibility, working and episodic memory, and processing speed.

RESULTS

Analysis of covariance between normotensive and CHT participants revealed lower cognitive performances on immediate and delayed recall and total number of words of the Rey Auditory Verbal Learning Test (P < 0.001). Spearman's correlations between BP loads and cognitive performances revealed inversed associations between diurnal systolic (SBP) loads and performances on the Trail Making Test Part B (TMTB) (P = 0.009), the TMTB-TMT Part A (P = 0.013), the Switching Cost of the color-word interference test (P = 0.020) and the Digit-Symbol Substitution Score tests (P = 0.018) in CHT. Diurnal diastolic (DBP) loads were inversely correlated to the TMTB (P = 0.014) and TMTB-TMT Part A (P = 0.006). In normotensive subjects, diurnal SBP loads were associated with the delayed recall of the Rey Auditory Verbal Learning Test (P = 0.031) and to the three components of the digit span (P < 0.05).

CONCLUSION

Diurnal BP loads are associated with lower cognitive performances in CHT individuals. These results suggest a lowering of target levels of diurnal BPs and/or its variability.

The association between serum uric acid level and the risk of cognitive impairment after ischemic stroke

Post-stroke cognitive impairment (PSCI) is a severe complication of stroke. Predicting PSCI is difficult because some risk factors for stroke, such as blood glucose level and blood pressure, are affected by many other elements. Although recent studies have shown that high serum uric acid (UA) levels are associated with cognitive dysfunction and may be a risk factor for PSCI, its impact remains unclear. Accordingly, the present study aimed to explore the association between serum UA level and PSCI. In total, 274 patients who experienced acute cerebral infarction, confirmed between January 2016 and December 2018, were enrolled. Baseline data and biological indicators were recorded. According to the Montreal Cognitive Assessment (MoCA) scores, patients were divided into two groups: PSCI and non-PSCI. Logistic regression analysis was used to determine possible risk factors for PSCI. Results demonstrated that serum UA levels were significantly higher in the PSCI group than in the non-PSCI group. Multivariable logistic analysis revealed that age, years of education, and UA level were independent risk factors for PSCI. PSCI patients were subdivided according to serum UA level: high and low. Hypertension history and homocysteine (Hcy) levels differed significantly between the high and low UA level groups. Further analysis revealed that a history of hypertension and Hcy demonstrated a certain correlation (r = 0.163, 0.162; P < 0.05), suggesting that serum UA level was an independent risk factor for PSCI. These findings indicate that serum UA level was correlated with PSCI in post-stroke patients and is anticipated to be used in clinical practice to reduce the incidence of PSCI.

Uric acid is associated with cognitive impairment in the elderly patients receiving maintenance hemodialysis-A two-center study

BACKGROUND

Elevated serum uric acid (SUA) has been associated with vascular cognitive impairment (CI) in the elderly. However, its relationship with cognitive function in the elderly patients receiving maintenance hemodialysis (MHD) has not yet been elucidated.

OBJECTIVE

The cognitive impairment is prevalent in MHD patients. Various insults may contribute to cognitive impairment in patients with MHD. The aim of this study was to investigate the relationship between SUA and CI in the elderly patients receiving MHD.

METHODS

A total of 180 elderly MHD subjects from two hospitals were enrolled in our study. Cognitive function domains were evaluated by MMSE at the beginning of the trial. Demographic and clinical characteristics were collected and recorded.

RESULTS

The subjects were stratified into quartiles according to SUA level. Demographic and clinical characteristics such as age, gender, smoking habit, education year, blood pressure (BP), hemoglobin, albumin, blood glucose (BG), total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), blood urea nitrogen (BUN), and serum creatinine (Scr) did not differ dramatically among groups (p > .05). The Q1 group showed the highest MMSE scores, and the Q4 group showed the lowest MMSE sores (p < .05). There was a negative correlation between SUA and MMSE scores (r = -.307, p = .014), and this correlation was independent of demographic and clinical characteristics.

CONCLUSIONS

Elevated SUA maybe contributes to CI in the elderly MHD patients. SUA level is independent risk for the CI in the elderly MHD patients.

Effects of allopurinol and febuxostat on cardiovascular mortality in elderly heart failure patients

Hyperuricemia is an emerging risk factor for the development of heart failure (HF) and is associated with a worsen prognosis of the disease. The effect of urate lowering drugs (ULT) and, in particular, the xanthine oxidase inhibitor in patients with HF is controversial. The aim of the study is to compare the effects of treatment with two different xanthine oxidase inhibitors (allopurinol or febuxostat) on cardiovascular mortality in elderly patients with chronic HF in a setting of clinical practice. In this observational trial, 255 elderly patients affected by chronic HF and treated with ULT on top of optimal medical treatment for HF. The sample included only outpatients with mild-to-moderate HF mainly secondary to chronic arterial hypertension or coronary artery disease and not previously hospitalized for HF. Patient treated with febuxostat (N. 120) and allopurinol (N. 135) were balanced for most of the baseline variables. In particular age, NYHA class distribution, drug treatment and renal function were comparable at the baseline and during the observation in both groups (p > 0.05). After a mean follow-up period of 5.1 years, the cumulative cardiovascular survival was 0.96 (95% CI 0.93-0.99) in febuxostat-treated patients and 0.89 (95% CI 0.84-0.93) in those treated with allopurinol. The between group difference, adjusted for the main confounding risk factors, was statistically significant (p = 0.04). Our study results suggest that possibility that febuxostat, a selective XO inhibitor, may favorably affect cardiovascular mortality in comparison with allopurinol in elderly patients with mild-to-moderate HF. This preliminary observation deserves further evaluation in the next future.

Cause-Specific Mortality in Gout: Novel Findings of Elevated Risk of Non-Cardiovascular-Related Deaths

OBJECTIVE

To examine cause-specific mortality beyond cardiovascular diseases (CVDs) in patients with gout compared to the general population.

METHODS

We included all residents of Skåne (Sweden) age ≥18 years in the year 2002. Using the Skåne Healthcare Register, we identified subjects with a new diagnosis of gout (2003-2013) and matched each person with gout with 10 comparators free of gout, by age and sex. We used information on the underlying cause of death from the Swedish Cause of Death Register (through December 31, 2014) to estimate hazard ratios (HRs, with 95% confidence intervals [95% CIs]) of mortality for specific causes of death in a multi-state Cox model, with adjustment for potential confounders.

RESULTS

Among 832,258 persons, 19,497 had a new diagnosis of gout (32% women) and were matched with 194,947 comparators. Subjects with gout had higher prevalence of chronic kidney disease, metabolic disease, and CVD. Gout was associated with 17% increased hazard of all-cause mortality overall (HR 1.17 [95% CI 1.14-1.21]), 23% in women (HR 1.23 [95% CI 1.17-1.30]), and 15% in men (HR 1.15 [95% CI 1.10-1.19]). In terms of cause-specific mortality, the strongest associations were seen in the relationship of gout to the risk of death due to renal disease (HR 1.78 [95% CI 1.34-2.35]), diseases of the digestive system (HR 1.56 [95% 1.34-1.83]), CVD (HR 1.27 [95% CI 1.22-1.33]), infections (HR 1.20 [95% CI 1.06-1.35]), and dementia (HR 0.83 [95% CI 0.72-0.97]).

CONCLUSION

Several non-CV causes of mortality are increased in persons with gout, emphasizing the need for improved management of comorbidities.

Gout and dementia in the elderly: a cohort study of Medicare claims

Background

Conflicting data in the literature raise the question whether gout, independent of its treatment, increases the risk of dementia in the elderly. Our objective was to assess whether gout in older adults is associated with the risk of incident dementia.

Methods

We used the 5% Medicare claims data for this observational cohort study. We used multivariable-adjusted Cox proportional hazard models to assess the association of gout with a new diagnosis of dementia (incident dementia), adjusting for potential confounders/covariates including demographics (age, race, sex), comorbidities (Charlson-Romano comorbidity index), and medications commonly used for cardiac diseases (statins, beta-blockers, diuretics, and angiotensin converting enzyme (ACE)-inhibitors) and gout (allopurinol and febuxostat).

Results

In our cohort of 1.71 million Medicare beneficiaries, 111,656 had incident dementia. The crude incidence rates of dementia in people without and with gout were 10.9 and 17.9 per 1000 person-years, respectively. In multivariable-adjusted analyses, gout was independently associated with a significantly higher hazard ratio of incident dementia, with a HR of 1.15 (95% CI, 1.12, 1.18); sensitivity analyses confirmed the main findings. Compared to age 65 to < 75 years, age 75 to < 85 and ≥ 85 years were associated with 3.5 and 7.8-fold higher hazards of dementia; hazards were also higher for females, black race or people with higher medical comorbidity.

Conclusion

Gout was independently associated with a 15% higher risk of incident dementia in the elderly. Future studies need to understand the pathogenic pathways involved in this increased risk.

Comparative effectiveness of allopurinol versus febuxostat for preventing incident dementia in older adults: a propensity-matched analysis

Background

The purpose of this study was to assess the comparative effectiveness of allopurinol versus febuxostat for preventing incident dementia in older adults.

Methods

In a retrospective cohort study using Medicare claims data, we included patients newly treated with allopurinol or febuxostat (baseline period of 365 days without either medication). We used 5:1 propensity-matched Cox regression analyses to compare the hazard ratio (HR) of incident dementia with allopurinol versus febuxostat use and with allopurinol/febuxostat dose and duration.

Results

Crude rates of incident dementia per 100,000 person-days were lower with higher daily dose: allopurinol less than 200, 200 to 299, and at least 300 mg/day with 12, 9, and 8 and febuxostat 40 and 80 mg/day with 9 and 8, respectively. In propensity-matched analyses, compared with allopurinol use, febuxostat use was not significantly different, and the HR of incident dementia was 0.79 (95% confidence interval (CI) 0.61, 1.03). Compared with allopurinol less than 200 mg/day, higher allopurinol doses (200 to 299 and at least 300 mg/day) and the febuxostat 40 mg/day dose were each associated with lower HRs of dementia: 0.80 (95% CI 0.64, 0.98), 0.59 (95% CI 0.50, 0.71), and 0.64 (95% CI 0.47, 0.86), respectively. Compared with allopurinol use for 1 to 180 days, longer allopurinol or febuxostat use durations were not significantly associated with differences in HR of dementia (range of 0.76 to 1.14).

Conclusions

A dose-related reduction in the risk of dementia in older adults was noted with higher allopurinol dose and with febuxostat 40 mg daily dose. Future studies need to examine the mechanism of this benefit.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1663-3) contains supplementary material, which is available to authorized users.

Sex-Dependent Associations of Serum Uric Acid with Brain Function During Aging

Serum uric acid (SUA) is an abundant natural antioxidant capable of reducing cellular oxidation, a major cause of neurodegenerative disease. In line with this, SUA levels are lower in Alzheimer's disease; however, the association between SUA and cognition remains unclear. Results from studies examining the effects of SUA on cognition may be difficult to interpret in the context of normal versus pathological aging. This study examined sex-specific associations of baseline SUA with cognition during aging. Data from dementia-free participants initially aged 26-99 (N = 1,451) recruited for the Baltimore Longitudinal Study of Aging (BLSA), were used in the current analyses. SUA was assessed using blood samples collected during research visits. Cognition was measured using five composite scores (verbal memory, attention, executive function, language, and visuospatial ability). At the first study visit, compared with women, men were older, more likely to be White, had more years of education, higher baseline SUA levels, and higher cardiovascular risk scores. Higher baseline SUA was associated with attenuated declines in attention (β= 0.006; p = 0.03) and visuospatial abilities (β= 0.007; p = 0.01) in men. There was a trend to suggest higher baseline SUA in men was associated with attenuated declines in language, but this finding did not reach statistical significance (p = 0.09). There were no significant findings with SUA and cognition in women. In this sample of cognitively healthy, community-dwelling adults, we found that higher SUA levels at baseline were associated with attenuated declines in attention and visuospatial abilities in men. SUA was not associated with cognition or change in cognition over time in women.

A Prospective Study on the Association between Uric Acid and Cognitive Function among Middle-Aged and Older Chinese

BACKGROUND

Uric acid (UA) is a powerful antioxidant that may have neuroprotective properties, yet it is also a risk factor of vascular disease that predisposes individuals to cognitive impairment. Results from longitudinal studies on UA and cognitive decline remain controversial.

OBJECTIVE

We examined the associations of baseline plasma UA level with follow-up cognitive function as well as cognitive decline over time among a large sample of middle-aged and older Chinese.

METHODS

Data from China Health and Retirement Longitudinal Study (CHARLS) were used. Cognitive function, including episodic memory, mental intactness, and global cognition, were tested twice with 2-year interval. Plasma UA was measured at baseline. Basic demographics, life habits, and health status were considered as potential confounders. Multiple linear regression models and mixed-effects regression models were fitted.

RESULTS

A total of 12,798 individuals aged above 45 years were eligible with the follow-up time ranging from 1.33 to 2.42 years. Both global cognitive function and mental intactness declined, while episodic memory remained stable over time. In multiple linear regression models, compared with the lowest baseline UA level, 3rd baseline UA quartile was associated with better follow-up global cognitive function (b = 0.425, p = 0.041) and episodic memory (b = 0.413, p = 0.004), and highest baseline UA quartile was associated with better follow-up mental intactness (b = 0.253, p = 0.041) in males; highest baseline UA level was associated with better follow-up cognition for each measure (b = 0.281∼0.768, p≤0.046) in females. Mixed-effects regression models suggested no significant baseline UA-by-time interactions on any cognitive measure.

CONCLUSION

Higher baseline UA level was associated with better cognition in later life but not with rates of cognitive decline among middle-aged and older Chinese.

Uric Acid Impairs Insulin Signaling by Promoting Enpp1 Binding to Insulin Receptor in Human Umbilical Vein Endothelial Cells

High levels of uric acid (UA) are associated with type-2 diabetes and cardiovascular disease. Recent pieces of evidence attributed to UA a causative role in the appearance of diabetes and vascular damage. However, the molecular mechanisms by which UA induces these alterations have not been completely elucidated so far. Among the mechanisms underlying insulin resistance, it was reported the role of a transmembrane glycoprotein, named either ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) or plasma cell antigen 1, which is able to inhibit the function of insulin receptor (I_R) and it is overexpressed in insulin-resistant subjects. In keeping with this, we stimulated human umbilical vein endothelial cells (HUVECs) with insulin and UA to investigate the effects of UA on insulin signaling pathway, testing the hypothesis that UA can interfere with insulin signaling by the activation of ENPP1. Cultures of HUVECs were stimulated with insulin, UA and the urate transporter SLC22A12 (URAT1) inhibitor probenecid. Akt and endothelial nitric oxide synthase (eNOS) phosphorylation levels were investigated by immunoblotting. ENPP1 binding to I_R and its tyrosine phosphorylation levels were tested by immunoprecipitation and immunoblotting. UA inhibited insulin-induced Akt/eNOS axis. Moreover, UA induced ENPP1 binding to I_R that resulted in an impairment of insulin signaling cascade. Probenecid reverted UA effects, suggesting that UA intracellular uptake is required for its action. In endothelial cells, UA directly interferes with insulin signaling pathway at receptor level, through ENPP1 recruitment. This evidence suggests a new molecular model of UA-induced insulin resistance and vascular damage.

Serum Uric Acid and Its Association with Longitudinal Cognitive Change Among Urban Adults

Uric acid, a waste metabolite among humans, was linked to various cognitive outcomes. We describe sex and age-group specific associations of baseline serum uric acid (SUAbase) and significant change in SUA (ΔSUA: 1 versus 0 = decrease versus no change; 2 versus 0 = increase versus no change) with longitudinal annual rate of cognitive change among a large sample of urban adults. Data from the Healthy Aging in Neighborhoods of Diversity across the Life Span study, 2004-2009 (visit 1) and 2009-2013 (visit 2) were used. Of 3,720 adults selected at baseline (age range: 30-64 y), complete data were available for N = 1,487-1,602 with a mean repeat of 1.5-1.7 visits/participant. Cognitive test domains spanned attention, processing speed, learning/memory, executive function, visuo-spatial/visuo-construction ability, language/verbal, and global cognitive function. SUA was measured at both visits. Multiple mixed-effects regression analyses were conducted. In the total population, a higher SUAbase was associated with a faster annual rate of decline on a measure of visual memory/visuo-construction ability (the Benton Visual Retention Test) by γ= 0.07 with a standard error of 0.02, p < 0.001. Among older men, a significant increase in SUA was associated with slower decline on a test of attention/processing speed, namely Trailmaking test, Part A, measured in seconds to completion (γ= -6.91 ± 1.73, p < 0.001). In sum, a higher SUAbase was associated with faster cognitive decline over-time in a visual memory/visuo-construction ability test. ΔSUA had particular beneficial effects of an increasing ΔSUA on the domain of attention/processing speed among older men. More longitudinal studies are needed to examine cognitive domain-specific effects of over-time change in SUA within sex and age groups.

Relationship between serum uric acid level and mild cognitive impairment in Chinese community elderly

BACKGROUND

To evaluate the association between SUA levels within a normal to high range and the risk of mild cognitive impairment (MCI) among community elderly.

METHODS

The present study was based on 2102 community elderly from a cross-sectional study conducted in a representative urban area of Beijing between 2009 and 2010. The mean age were 71.2 ± 6.6 years old, 59.7% were female. Mini-Mental State Examination (MMSE) was used to assess cognitive function by trained neurology doctors.

RESULTS

The prevalence of hyperuricemia and MCI was 16.7% and 15.9% respectively. With the increase of SUA levels, the prevalence of MCI showed a strong decreasing linear trend. Multiple logistic regression analysis showed ORs for MCI were 1.01(95% CI: 0.69-1.48), 1.50(95% CI: 0.85-2.64), 1.65(95% CI: 1.12-2.43) and 1.53(95% CI: 1.00-2.33), 1.84(95% CI: 1.27-2.90), 1.92(95% CI: 1.02-3.35) for the second, third and highest quarters among men and women respectively (with the lowest quartile as the reference).

CONCLUSIONS

Higher SUA levels, when in the normal range, were positively associated with cognitive function among Chinese community elderly, but this association was not robust among participants with hyperuricemia.

Uric acid and incident dementia over 12 years of follow-up: a population-based cohort study

OBJECTIVES

In patients with gout, maintaining too low serum uric acid (SUA) level with urate-lowering therapy is a concern because uric acid is thought to be neuroprotective. However, the relation between SUA and dementia remains debated. This study aimed to investigate the impact of SUA level on the incidence of dementia.

METHODS

We assessed the longitudinal association between SUA level and incident dementia (Diagnostic and Statistical Manual of Mental Disorders Version IV (DSM-IV) criteria) in a large cohort of healthy older people from the community (Three-City Dijon cohort). Additionally, we investigated the relation between SUA level and MRI markers of brain ageing (white matter hyperintensity volume (WMHV), lacunes and hippocampal volume).

RESULTS

The study sample comprised 1598 people (mean (SD) age 72.4(4.1) years, 38.3% male). During the 13,357 person-years of follow-up (median duration: 10.1 years), dementia developed in 110 participants (crude incidence rate: 8.2/1000 person-years). After multiple adjustments, the multivariate HR with the highest (≥75th percentile) versus lowest SUA level was 1.79 (95% CI 1.17 to 2.73; p=0.007). The association was stronger with vascular or mixed dementia (HR=3.66 (95% CI 1.29 to 10.41), p=0.015) than Alzheimer's disease (HR=1.55 (95% CI 0.92 to 2.61), p=0.10). There was a non-significant trend towards an association between high SUA level and extensive WMHV (p=0.10), a biomarker of small vessel disease, but not hippocampal volume (p=0.94) or lacunes (p=0.86). The association between SUA level and vascular or mixed dementia might be affected by interim strokes.

CONCLUSIONS

Risk of dementia, especially vascular or mixed dementia, may be increased with high SUA levels in elderly people.

Risk reclassification ability of uric acid for cardiovascular outcomes in essential hypertension

BACKGROUND

Hyperuricemia is associated with incident cardiovascular events in different settings of patients. We tested whether the inclusion of uric acid (UA) in Cox models including standard risk factors allows to better stratify cardiovascular risk in a cohort of 1522 naïve hypertensives with preserved renal function.

METHODS

We used multiple Cox regression models to assess the independent effect of UA on cardiovascular outcomes, and Harrell'C index, Net Reclassification Index (NRI), and Integrated Discrimination Improvement (IDI) as indicators of the additional prognostic value of UA beyond and above that provided by standard risk factors and estimated glomerular filtration rate (e-GFR). Study outcomes were fatal and nonfatal cardiovascular events and fatal and nonfatal coronary outcomes/death due to other cardiovascular events.

RESULTS

UA resulted strongly related to both outcomes in unadjusted Cox regression analyses (P<0.001). Inclusion of UA into multiple Cox regression models including Framingham risk factors and e-GFR did not affect the association between UA and outcomes (fatal and nonfatal cardiovascular events, HR=1.44, 95% CI=1.36-1.55, P<0.001; fatal and nonfatal coronary outcomes/death due to other cardiovascular events, HR=1.48, 95% CI=1.36-1.61, P<0.001). Inclusion of UA into basic Cox models provided an increase in all indexes of prognostic accuracy for both outcomes: Harrell'C index: +5%; NRI: +24.9%; IDI: +7.6%, all P<0.001; and Harrell'C index: +5%; NRI: +25%; IDI: +6.3%, all P<0.001, respectively.

CONCLUSIONS

UA is an independent predictor of cardiovascular outcomes and increases prognostic accuracy of Cox models, including Framingham risk factors and e-GFR, in hypertensives with normal renal function, allowing a risk reclassification.

Fructose Intake, Serum Uric Acid, and Cardiometabolic Disorders: A Critical Review

There is a direct relationship between fructose intake and serum levels of uric acid (UA), which is the final product of purine metabolism. Recent preclinical and clinical evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, and cardiovascular disease. It is probably also an independent risk factor for chronic kidney disease, Type 2 diabetes, and cognitive decline. These relationships have been observed for high serum UA levels (>5.5 mg/dL in women and >6 mg/dL in men), but also for normal to high serum UA levels (5-6 mg/dL). In this regard, blood UA levels are much higher in industrialized countries than in the rest of the world. Xanthine-oxidase inhibitors can reduce UA and seem to minimize its negative effects on vascular health. Other dietary and pathophysiological factors are also related to UA production. However, the role of fructose-derived UA in the pathogenesis of cardiometabolic disorders has not yet been fully clarified. Here, we critically review recent research on the biochemistry of UA production, the relationship between fructose intake and UA production, and how this relationship is linked to cardiometabolic disorders.

Serum uric acid is associated with better executive function in men but not in women: Baseline assessment of the ELSA-Brasil study

BACKGROUND

Serum uric acid (SUA) may protect against free radical stress damage and was previously linked to cognitive impairment in older adults, but evidence in middle-aged adults is scarce.

PURPOSE

We sought to analyze whether SUA is associated with cognitive performance in apparently healthy middle-aged participants in the ELSA-Brasil cohort study.

METHODS

We excluded participants older than age 65, those taking allopurinol, benzbromarone, or medications that could impair cognitive performance, those with previous stroke, and those with incomplete data on cognitive tests or SUA. The Consortium to Establish a Registry for Alzheimer's Disease Word List Memory Test (CERAD-WLMT), the Semantic Fluency Test (SFT), and the Trail Making Test version B (TMT) were used as dependent variables. Sex-specific linear regression models were used to assess the association between SUA and cognitive tests, adjusted by age, education, hypertension, dyslipidemia, diabetes, smoking, alcohol consumption, body mass index, coronary heart disease, renal function, depression, aspirin use, thyroid function, and menopausal status (in women). We used the Bonferroni procedure to control for the false discovery rate associated with multiple comparisons.

RESULTS

We analyzed cross-sectional data from 6751 women and 5464 men. Mean age and standard deviation (SD) of the sample was 49.6 (SD 7.4) years for men and 49.9 (SD 7.3) years for women. The majority of men (52%) and women (51%) were white. Mean SUA value was 4.75 (SD 1.16) mg/dL in women and 6.44 (SD 1.39) mg/dL in men. Multivariate linear models showed no association in women and a significant inverse association between SUA levels and TMT (β=-3.106, 95% CI=-4.594; -1.618, p=0.0004) in men.

CONCLUSION

In a middle-aged subset population, SUA is associated with better performance on an executive function test in men, but not in women in the ELSA-Brasil cohort study.

Serum uric acid and impaired cognitive function in community-dwelling elderly in Beijing

The relationship between serum uric acid (sUA) and cognitive function is contradictory. This study assessed the association between sUA and cognitive impairment in 10,039 community-dwelling subjects aged ≥55years living in Beijing, China. Participants underwent determination of sUA and an evaluation of cognitive function using the scholarship-adjusted Mini-Mental State Examination (MMSE): MMSE ≤17 for illiterates; MMSE≤20 for primary school graduates (≥6years of education); and MMSE≤24 for junior school graduates or above (≥9years of education). Among the 10016 persons with valid MMSE scores, the prevalence of cognitive impairment was 9.14%. A multivariate logistic regression model including demographic, clinical and genetic parameters was performed to assess the relationship between sUA and cognitive impairment. Persons with cognitive impairment had lower sUA levels than those with normal cognitive function: (302.30±82.80 vs. 312.20±84.01μmol/L, p=0.001). After adjusting for age, sex, lifestyle, relevant diseases and the apolipoprotein E (APOE) ε4 allele, stepwise logistic regression showed that participants with higher levels of sUA had a lower risk of cognitive impairment (hazard ratio (HR): 0.78; 95% confidence interval (CI): 0.62-0.96; p=0.022). In this baseline cross-sectional population-based sample, high levels of sUA were associated with a decreased risk of cognitive impairment.

Uric Acid and Neurocognitive Function in Survivors of Childhood Acute Lymphoblastic Leukemia Treated with Chemotherapy Only

BACKGROUND

Hyperuricemia is implicated in cardiovascular and cerebrovascular diseases. This study evaluated associations between uric acid (UA), cardiovascular health, and neurocognitive function in adolescent and adult survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only.

METHODS

126 adolescent [mean (SD) age 14.6 (5.0); 7.8 (1.7) years postdiagnosis] and 226 adult survivors [age 25.4 (4.2) years; 18.1 (4.4) years postdiagnosis] completed comprehensive neurocognitive testing. Concurrent UA measurements were conducted for both groups. For adult survivors, cardiovascular risk factors were assessed, and UA measurements during adolescence [12.3 (4.0) years before neurocognitive testing] were also collected. UA levels were categorized into quartiles for age- and gender-based ranking, and associations with neurocognitive outcomes were examined.

RESULTS

Survivors demonstrated worse attention, processing speed, and executive functions than population norms (P values < 0.05). Adolescent survivors with elevated UA had poorer attention (P = 0.04), visual-processing speed (P = 0.03), and cognitive flexibility (P = 0.02). UA was not associated with neurocognitive outcomes in adult survivors. Adult survivors developed dyslipidemia (46%), hypertension (32%), and abdominal obesity (26%), and high UA during adolescence was associated with these cardiovascular risk factors as adults (all P values < 0.01). Fine-motor processing speed was slower in adult survivors with dyslipidemia (P = 0.04) and abdominal obesity (P = 0.04). Poorer attention was marginally associated with hypertension (P = 0.06).

CONCLUSIONS

Elevated UA is associated with neurocognitive performance in adolescent survivors. In adult survivors, relative elevation of UA during adolescence was predictive of cardiovascular health, which was associated with poorer neurocognitive outcomes.

IMPACT

Future studies should evaluate the mediating role of chronic cardiovascular health conditions between elevated UA and subsequent neurocognitive impairment in survivors. Cancer Epidemiol Biomarkers Prev; 25(8); 1259-67. ©2016 AACR.

Association of cognitive function and serum uric acid: Are cardiovascular diseases a mediator among women?

BACKGROUND

Several studies reported an association between concentrations of serum uric acid and cognitive function, but the evidence is contradictory. It is known that uric acid is associated with cardiovascular diseases, especially among women. Stratifying by sex and history of cardiovascular disease may clarify whether uric acid is an independent risk factor for cognitive dysfunction.

METHODS

A population-based study was conducted in the German State of Saarland. A subgroup of participants aged ≥70years underwent a comprehensive assessment of cognitive function. Linear regression models and restricted cubic spline functions were used to assess association of uric acid with cognitive performance in 1144 study participants.

RESULTS

High levels of uric acid were associated with worse cognitive performance among women (-0.57; 95% CI: -1.10 to -0.04) but not among men (-0.12; 95% CI: -0.64 to 0.39). The association was much stronger among the subgroup of women with cardiovascular diseases (-1.91; 95% CI: -3.15 to -0.67) and also revealed a dose-response relationship in this subgroup.

CONCLUSIONS

Serum uric acid showed an inverse association with cognitive function among women and the association was amplified by the presence of cardiovascular disease. These results highlight the importance of stratifying by sex and cardiovascular disease in future studies on uric acid and cognition.

GWAS and transcriptional analysis prioritize ITPR1 and CNTN4 for a serum uric acid 3p26 QTL in Mexican Americans

Background

The variation in serum uric acid concentrations is under significant genetic influence. Elevated SUA concentrations have been linked to increased risk for gout, kidney stones, chronic kidney disease, and cardiovascular disease whereas reduced serum uric acid concentrations have been linked to multiple sclerosis, Parkinson’s disease and Alzheimer’s disease. Previously, we identified a novel locus on chromosome 3p26 affecting serum uric acid concentrations in Mexican Americans from San Antonio Family Heart Study. As a follow up, we examined genome-wide single nucleotide polymorphism data in an extended cohort of 1281 Mexican Americans from multigenerational families of the San Antonio Family Heart Study and the San Antonio Family Diabetes/Gallbladder Study. We used a linear regression-based joint linkage/association test under an additive model of allelic effect, while accounting for non-independence among family members via a kinship variance component.

Results

Univariate genetic analysis indicated serum uric acid concentrations to be significant heritable (h² = 0.50 ± 0.05, p < 4 × 10⁻³⁵), and linkage analysis of serum uric acid concentrations confirmed our previous finding of a novel locus on 3p26 (LOD = 4.9, p < 1 × 10⁻⁵) in the extended sample. Additionally, we observed strong association of serum uric acid concentrations with variants in following candidate genes in the 3p26 region; inositol 1,4,5-trisphosphate receptor, type 1 (ITPR1), contactin 4 (CNTN4), decapping mRNA 1A (DCP1A); transglutaminase 4 (TGM4) and rho guanine nucleotide exchange factor (GEF) 26 (ARHGEF26) [p < 3 × 10⁻⁷; minor allele frequencies ranged between 0.003 and 0.42] and evidence of cis-regulation for ITPR1 transcripts.

Conclusion

Our results confirm the importance of the chromosome 3p26 locus and genetic variants in this region in the regulation of serum uric acid concentrations.

Serum uric acid level and association with cognitive impairment and dementia: systematic review and meta-analysis

Serum uric acid (sUA) level may be associated with cognitive impairment/dementia. It is possible this relationship varies with dementia subtype, particularly between vascular dementias (VaD) and Alzheimer's (AD) or Parkinson's disease (PDD)-related dementia. We aimed to present a synthesis of all published data on sUA and relationship with dementia/cognition through systematic review and meta-analysis. We included studies that assessed the association between sUA and any measure of cognitive function or a clinical diagnosis of dementia. We pre-defined subgroup analyses for patients with AD, VaD, PDD, mild cognitive impairment (MCI), and mixed or undifferentiated. We assessed risk of bias/generalizability, and where data allowed, we performed meta-analysis to describe pooled measures of association across studies. From 4811 titles, 46 papers (n = 16,688 participants) met our selection criteria. Compared to controls, sUA was lower in dementia (SDM -0.33 (95%CI)). There were differences in association by dementia type with apparent association for AD (SDM -0.33 (95%CI)) and PDD (SDM -0.67 (95%CI)) but not in cases of mixed dementia (SDM 0.19 (95%CI)) or VaD (SDM -0.05 (95%CI)). There was no correlation between scores on Mini-Mental State Examination and sUA level (summary r 0.08, p = 0.27), except in patients with PDD (r 0.16, p = 0.003). Our conclusions are limited by clinical heterogeneity and risk of bias in studies. Accepting this caveat, the relationship between sUA and dementia/cognitive impairment is not consistent across all dementia groups and in particular may differ in patients with VaD compared to other dementia subtypes.

Epidemiology and health-related services

PURPOSE OF REVIEW

This article presents recent epidemiologic contributions focusing on gout-related conditions, especially if controversial, to find plausible, despite hypothetical, mechanistic explanations from the clinician perspective.

RECENT FINDINGS

The prevalence of gout is increasing, but it is only partially clear that the incidence may be increasing as well. Direct associations of gout with increased risk of diabetes, black races, neurodegenerative disorders, and sugar-enriched foods have been recently questioned. A negative association with smoking has been reported, and new evidence shows that the impact of diet may be independent of obesity. Kidney disease and diuretics have been confirmed to be associated with gout, whereas new data on aging and menopause have come to challenge apparently established disease mechanisms. Regarding treatments, increase in bladder cancer associated with chronic allopurinol use has been reported, and the positive effect of urate-lowering treatment on cardiovascular events has been contested.

SUMMARY

Epidemiological data in gout-related conditions are still evolving and claim for future cohort or intervention studies to prove causality. Controversies in epidemiological results fertilize the ground for studies to prove mechanisms and causality and provides a unique opportunity for clinical intervention to improve outcomes, especially with regard to treatments.

Effects of coffee consumption on serum uric acid: systematic review and meta-analysis

OBJECTIVE

Study results on the effects of coffee consumption on serum uric acid (UA) have been conflicting. The aim of this study is to analyze the literature regarding the effect of coffee consumption on serum UA.

METHODS

We searched MEDLINE, EMBASE, the Cochrane library, and KoreaMed for all articles published before January 2015. Studies with quantitative data on coffee consumption and serum UA level were included. Coffee consumption and serum UA level were identified with/without the risk of gout.

RESULTS

Nine studies published between 1999 and 2014 were included, containing a total of 175,310 subjects. Meta-analysis demonstrated that coffee has a significantly lowering effect on serum UA, where there are gender differences in the amount of coffee required to lower serum UA. Women (4-6 cups/day) need more coffee to lower serum UA than men (1-3 cups/day). Meta-analysis showed that coffee intake of 1 cup/day or more was significantly associated with reduction of the risk of gout, with a negative correlation with the amount of daily coffee intake for both genders.

CONCLUSIONS

This is the first systematic review on the effects of coffee consumption on serum UA. Based on our study, moderate coffee intake might be advocated for primary prevention of hyperuricemia and gout in both genders.

Uric acid is an independent predictor of cardiovascular events in post-menopausal women

BACKGROUND

Uric acid (UA) is a risk factor for cardiovascular (CV) disease. In post-menopause UA levels are increased and strongly associated with subclinical organ damage. We investigated the prognostic significance of UA levels in predicting CV morbidity and mortality in post-menopausal women.

METHODS

We considered 645 post-menopausal outpatients not taking hormone replacement therapy or any drugs interfering with UA levels. We evaluated major adverse cardiovascular events (MACE) as primary endpoint, with coronary, stroke or total events as secondary endpoint. Survival curves for tertiles of UA were obtained by using the Kaplan-Meier and Mantel methods. Effect of prognostic factors on survival was evaluated by multivariable Cox regression model, considering P<0.05 as statistically significant.

RESULTS

During a mean (SD) follow-up at 72.5 (23.5) months, there were 90 new CV events (2.31%): 62 coronary and 28 cerebrovascular events. The rate of nonfatal CV events (3.15% versus 2.03% and 1.52%, P=0.009) as well as that of MACE (3.23% versus 2.11% and 1.59%, P=0.011) were significantly higher in the third tertile than in the other two groups. Interestingly, cerebrovascular (1.15% versus 0.62% and 0.30%, P=0.027) but not coronary events were significantly different among the three groups. In the Cox regression model, UA was independently and strongly associated with the incident risk of MACE (HR=1.248, P=0.001), cerebrovascular (HR=1.657, P<0.0001) and total events (HR=1.391, P<0.0001).

CONCLUSIONS

In post-menopause, independently of other CV risk factors and menopause duration, UA levels are associated with increased risk of death and MACE, in particular cerebrovascular but not coronary events.