Serum urate levels and neurodegenerative outcomes: a prospective cohort study and mendelian randomization analysis of the UK Biobank.

BACKGROUND: Previous studies on the associations between serum urate levels and neurodegenerative outcomes have yielded inconclusive results, and the causality remains unclear. This study aimed to investigate whether urate levels are associated with the risks of Alzheimer's disease and related dementias (ADRD), Parkinson's disease (PD), and neurodegenerative deaths. METHODS: This prospective study included 382,182 participants (45.7% men) from the UK Biobank cohort. Cox proportional hazards models were used to assess the associations between urate levels and risk of neurodegenerative outcomes. In the Mendelian randomization (MR) analysis, urate-related single-nucleotide polymorphisms were identified through a genome-wide association study. Both linear and non-linear MR approaches were utilized to investigate the potential causal associations. RESULTS: During a median follow-up period of 12 years, we documented 5,400 ADRD cases, 2,553 PD cases, and 1,531 neurodegenerative deaths. Observational data revealed that a higher urate level was associated with a decreased risk of ADRD (hazard ratio [HR]: 0.93, 95% confidence interval [CI]: 0.90, 0.96), PD (HR: 0.87, 95% CI: 0.82, 0.91), and neurodegenerative death (HR: 0.88, 95% CI: 0.83, 0.94). Negative linear associations between urate levels and neurodegenerative events were observed (all P-values for overall < 0.001 and all P-values for non-linearity > 0.05). However, MR analyses yielded no evidence of either linear or non-linear associations between genetically predicted urate levels and the risk of the aforementioned neurodegenerative events. CONCLUSION: Although the prospective cohort study demonstrated that elevated urate levels were associated with a reduced risk of neurodegenerative outcomes, MR analyses found no evidence of causality.

Joint association of serum urate and healthy diet with chronic obstructive pulmonary disease incidence: results from the UK Biobank study.

Background: The role of serum urate (SU) levels in the development of chronic obstructive pulmonary disease (COPD) remains a topic of debate, and it is unclear whether a healthy diet can mitigate the impact of SU on COPD risk. The objective of this study is to examine whether and to what extent a healthy diet can reduce the risk of COPD in relation to SU levels. Methods: The cohort analysis included 155 403 participants from the UK Biobank. SU levels were measured at the time of recruitment. A healthy diet score was calculated based on the consumption of vegetables, fruits, fish, processed meats, unprocessed red meat, whole grains, and refined grains. The Cox proportional hazards model was used to analyze the associations between SU levels, a healthy diet score, and the risk of COPD. Results: During a follow-up period of 1 409 969 person-years, 2918 incident cases of COPD were identified. Compared with the lowest SU level group, the hazard ratio (HR) and 95% confidence interval (CI) for COPD were 1.17 (1.03, 1.34) for participants with the highest SU level (hyperuricemia), indicating a positive association. Additionally, a dose-response relationship was observed between SU levels and the incidence of COPD (P-value for overall <0.0001). In the combined effect analysis, compared to individuals with high SU (hyperuricemia) + a low diet score (diet score <4), those with normal SU + a high diet score (diet score ≥4) had a HR (95% CI) of 0.75 (0.65, 0.87) for COPD. Conclusions: In summary, there is a positive association between SU levels and the risk of COPD. Furthermore, a healthier diet can mitigate the risk of COPD associated with high SU levels.