【Abstract】 Objective To investigate the relationship between plasma homocysteine (Hcy), uric acid(UA) levels and cognitive functions, behavioural and psychological symptoms of dementia (BPSD) in Alzheimer's disease. Methods The plasma Hcy, UA levels were measured and compared in 86 patients with AD and 90 normal healthy persons. Patients in AD group were divided into cognitive normal group and mild, moderate, severe dementia group by using minimental state examination (MMSE) and the Clinical Dementia Scale (CDR) to evaluate the cognitive function. Patients in AD group were divided into BPSD group and nonBPSD group by using the neuropsychology questionnaire (NPI) to evaluate The symptoms of mental behavior. Multivariate logistic regression analysis was used to assess the risk factors for cognitive decline in AD patients. Results Multivariate logistic regression analysis showed that cognitive decline in AD patients was associated with advanced age, high Hcy level, and low UA level (P＜005), but not related to SBP, DBP, gender, education level, TG, TC, FBG, HbA1 (%). 005). The blood UA level in the AD group was significantly lower than that in the control group (P＜005), while the plasma Hcy level was significantly higher than the control group (P＜005). Compare with mild, moderate, and severe AD groups, the more dementia in AD patients, the higher plasma Hcy levels and the lower serum UA levels were detected. Plasma Hcy levels in BPSD group were higher than nonBPSD group(P＜005). Conclusions Age, high Hcy, and low UA levels are risk factors for cognitive decline in AD patients. Plasma levels of Hcy and UA are associated with the severity of dementia in AD patients. High Hcy levels are associated with mental behavioral symptoms in AD patients.