Association between serum uric acid levels and cerebral white matter lesions in Chinese individuals

Associations of serum uric acid variability with neuroimaging metrics and cognitive decline: a population-based cohort study

BACKGROUND

The relationship between variation in serum uric acid (SUA) levels and brain health is largely unknown. This study aimed to examine the associations of long-term variability in SUA levels with neuroimaging metrics and cognitive function.

METHODS

This study recruited 1111 participants aged 25-83 years from a multicenter, community-based cohort study. The SUA concentrations were measured every two years from 2006 to 2018. We measured the intraindividual SUA variability, including the direction and magnitude of change by calculating the slope value. The associations of SUA variability with neuroimaging markers (brain macrostructural volume, microstructural integrity, white matter hyperintensity, and the presence of cerebral small vessel disease) and cognitive function were examined using generalized linear models. Mediation analyses were performed to assess whether neuroimaging markers mediate the relationship between SUA variation and cognitive function.

RESULTS

Compared with the stable group, subjects with increased or decreased SUA levels were all featured by smaller brain white matter volume (beta =  - 0.25, 95% confidence interval [CI] - 0.39 to - 0.11 and beta =  - 0.15, 95% CI - 0.29 to - 0.02). Participants with progressively increased SUA exhibited widespread disrupted microstructural integrity, featured by lower global fractional anisotropy (beta =  - 0.24, 95% CI - 0.38 to - 0.10), higher mean diffusivity (beta = 0.16, 95% CI 0.04 to 0.28) and radial diffusivity (beta = 0.19, 95% CI 0.06 to 0.31). Elevated SUA was also associated with cognitive decline (beta =  - 0.18, 95% CI - 0.32 to - 0.04). White matter atrophy and impaired brain microstructural integrity mediated the impact of SUA increase on cognitive decline.

CONCLUSIONS

It is the magnitude of SUA variation rather than the direction that plays a critical negative role in brain health, especially for participants with hyperuricemia. Smaller brain white matter volume and impaired microstructural integrity mediate the relationship between increased SUA level and cognitive function decline. Long-term stability of SUA level is recommended for maintaining brain health and preventing cognitive decline.

Lower serum uric acid and impairment of right cerebral hemisphere structural brain networks are related to depressive symptoms in cerebral small vessel disease: A cross-sectional study

Cerebral small vessel disease (SVD) may be associated with an increased risk of depressive symptoms. Serum uric acid (SUA), an antioxidant, may be involved in the occurrence and development of depressive symptoms, but the mechanism remains unknown. Moreover, the relationship between structural brain networks and SUA has not been explored. This study examined the relationship between SUA and depressive symptoms in patients with SVD using graph theory analysis. We recruited 208 SVD inpatients and collected fasting blood samples upon admission. Depressive symptoms were assessed using the 24-item Hamilton Depression Rating Scale (HAMD-24). Magnetic resonance imaging was used to evaluate SVD, and diffusion tensor images were used to analyze structural brain networks using graph theory. Patients with depressive symptoms (n = 34, 25.76%) compared to those without (334.53 vs 381.28 μmol/L, p = 0.017) had lower SUA levels. Graph theoretical analyses showed a positive association of SUA with betweenness centrality, nodal efficiency, and clustering coefficients and a negative correlation with the shortest path length in SVD with depressive symptoms group. HAMD scores were significantly associated with nodal network metrics in the right cerebral hemisphere. Our findings suggested that lower SUA levels are significantly associated with disrupted structural brain networks in the right cerebral hemisphere of patients with SVD who have depressive symptoms.

The relationship between uric acid and brain health from observational studies

This study conducts a systematic literature review and meta-analysis regarding the potential influence of serum uric acid levels on cerebral small vessel diseases and the cognitive status in the prodromal stages of dementia. We identified four different cerebral small vessel diseases and three specific domains of cognitive performance to be considered in the literature search. The analysis contained 14 studies (13 cross-sectional design and one longitudinal design) with 11,502 participants measuring the relationship between uric acid and cerebral small vessel disease. In both continuous and categorical analyses, significant associations were found between hyperuricemia and cerebral small vessel diseases (continuous data: pooled OR: 1.00, 95%CI: 1.00-1.01 and categorical data: pooled OR: 1.42, 95%CI: 1.15-1.75). For the relationship between uric acid and cognitive performance, 19 studies with 49,901 participants were considered, including eight cohort studies, and 11 cross-sectional studies. The cross-sectional data showed that a marginal relationship existed between uric acid and global cognition (β: 0.00, 95%CI: -0.01-0.00). The pooled analysis of cohort studies indicated that higher uric acid had a deleterious effect on attention and executive function (continuous data: β: -0.02, 95%CI: -0.04-0.00 and categorical data: β: -0.03, 95%CI: -0.07-0.00). Conclusion: Our study indicated that a higher level of uric acid had an adverse effect on brain health. Furthermore, a high level of uric acid is related to cognitive decline in attention and executive function, which may exist a long time before the diagnosis of dementia.

Can hyperuricemia predict the progression risk of cerebral small vessel disease?

AIMS

Uric acid (UA) may play a crucial role in the process of cerebral small vessel disease (SVD), but few follow-up studies have focused on the effect of UA in the progression of SVD. The present study aimed to ascertain whether serum UA levels are associated with the risk of SVD progression.

METHODS

We performed an observational clinical study in adults older than 45 years with cranial magnetic resonance imaging (MRI) from 30 October 2015, to 28 January 2021. The patients were divided into two groups according to whether their total burden of SVD scores increased or not during the follow-up: SVD progression (increased by at least one point) and without SVD progression (increased 0 points). Cox regression and Kaplan-Meier survival analyses were used for univariate analysis between groups to identify the risk factors for SVD progression.

RESULTS

Ultimately, 261 eligible patients were included in the final analysis. Of the 261 eligible patients, 73 were included in the SVD progression group, and 188 were included in the group without SVD progression. Correlation analysis found that the levels of UA and the ratio of hyperuricemia (HUA) showed statistically significant correlations with SVD progression risk (r = 0.197 and Crammer's V = 0.213, respectively, P < 0.01). Cox regression and Kaplan-Meier survival analyses showed that after adjustment for covariates, HUA was an independent risk factor for the incidence of SVD progression. The risk of SVD progression in patients with HUA was higher than that in those without HUA (HR (95% CI), 1.77 (1.03-3.05), P < 0.05).

CONCLUSIONS

High serum UA levels are independently related to the risk of SVD progression, thus highlighting not only the influence of traditional risk factors such as hypertension and age on SVD but also the UA levels of patients for individualized treatment.

Hyperuricemia, Gout, and the Brain-an Update

PURPOSE OF REVIEW

This review aims to summarize recent evidence regarding the complex relationship between uric acid (UA), gout, and brain diseases.

RECENT FINDINGS

Observational studies have suggested that patients with hyperuricemia or gout might have a decreased risk of neurodegenerative diseases. Conversely, they may be at increased risk of cerebrovascular disease. Mendelian randomization (MR) studies use a genetic score as an instrumental variable to address the causality of the association between a risk factor (here, UA or gout) and an outcome. So far, MR analyses do not support a causal relationship of UA or gout with Alzheimer's disease and dementia, and of UA with Parkinson's disease or stroke. Observation studies indicate a U-shaped association between UA and brain diseases, but MR studies do not support that this association is causal. Further studies should address the causal role of gout as well as the impact of urate-lowering therapy on these outcomes.

Is microvascular dysfunction a systemic disorder with common biomarkers found in the heart, brain, and kidneys? - A scoping review

Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and 2019 that measured blood biomarkers of MVD in three vital organs i.e. brain, heart, and the kidney. Of the 9706 unique articles 321 met the criteria, reporting 49 biomarkers of which 16 were common to the three organs. Endothelial dysfunction, inflammation including reactive oxidation, immune activation, and coagulation were the commonly recognized pathways. Triglyceride, C-reactive protein, Cystatin C, homocysteine, uric acid, IL-6, NT-proBNP, thrombomodulin, von Willebrand Factor, and uric acid were increased in MVD of all three organs. In contrast, vitamin D was decreased. Adiponectin, asymmetric dimethylarginine, total cholesterol, high-density and low-density cholesterol were found to be variably increased or decreased in studies. We review the pathways underlying MVD in the three organs and summarize evidence supporting its systemic nature. This scoping review informs clinicians and researchers in the multi-system manifestation of MVD. Future work should focus on longitudinal investigations to evaluate the multi-system involvement of this disease.

Serum Uric Acid is Independently Associated with Enlarged Perivascular Spaces

Enlarged perivascular spaces (EPVS) are reported to be associated with impaired cognitive function and sleep disorders. It is of clinical importance to understand the risk factors for EPVS. Hyperuricemia increases the risk of hypertension and endothelial dysfunction, which are well recognized to be associated with EPVS. Therefore, we postulated that serum uric acid (SUA) might be associated with EPVS. A total of 665 lacunar stroke patients were enrolled in this study. The SUA concentrations of patients with severe EPVS were much higher than those of patients with mild EPVS (for basal ganglia: 5.25 ± 1.40 mg/dl vs. 4.75 ± 1.40 mg/dl, p < 0.001; for white matter: 5.31 ± 1.41 mg/dl vs. 4.88 ± 1.37 mg/dl, p = 0.009). The percentage of subjects with severe EPVS tended to be higher in the highest quartile of SUA (chi-square test: P = 0.002 for basal ganglia and 0.006 for white matter). Spearman correlation analysis indicated that the SUA concentrations were positively correlated with the severity of EPVS (rho > 0, p < 0.05). Multivariate logistic regression analysis showed that high normal SUA was independently associated with a higher severity of EPVS. This finding suggests that high SUA levels might be an independent risk factor for EPVS in lacunar stroke patients.