Relationships between Serum Lipid, Uric Acid Levels and Mild Cognitive Impairment in Parkinson's Disease and Multiple System Atrophy

Background: Mild cognitive impairment is one of the non-motor symptoms in Parkinson's disease (PD) and multiple system atrophy (MSA). Few studies have previously been conducted on the correlation between serum uric acid (SUA) and lipid levels and mild cognitive impairment in PD and MSA. Methods: Participants included 149 patients with PD and 99 patients with MSA. The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to evaluate cognitive function. Evaluations were conducted on SUA and lipid levels, which included triglyceride, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and total cholesterol (TC). Results: Patients with PD and MSA diagnosed with mild cognitive impairment demonstrated multiple cognitive domain impairment when compared with patients with normal cognition. Attentional impairment was more pronounced in patients with MSA when compared with PD (p = 0.001). In PD, the risk of mild cognitive impairment was lower in the highest quartiles and secondary quartile of SUA than in the lowest quartiles (odds ratio [OR] = 0.281, 95% confidence intervals [CI]: 0.097–0.810, p = 0.019; and OR = 0.317, 95% CI: 0.110–0.911, p = 0.033). In MSA, the risk of mild cognitive impairment was lower in the third and highest quartile of SUA than in the lowest quartile (OR = 0.233, 95% CI: 0.063–0.868, p = 0.030; and OR = 0.218, 95% CI: 0.058–0.816, p = 0.024). In patients with PD, the MoCA scores were negatively correlated with TC levels (r = –0.226, p = 0.006) and positively correlated with SUA levels (r = 0.206, p = 0.012). In MSA, the MoCA scores were positively correlated with SUA levels (r = 0.353, p = 0.001). Conclusions: Lower SUA levels and higher TC levels are a possible risk factor for the risk and severity of mild cognitive impairment in PD. Lower SUA levels are a possible risk factor for the risk and severity of mild cognitive impairment in MSA.