Investigation on plasma homocysteine level and cognition in population at high risk for stroke in Xi'an

OBJECTIVE: To investigate the relationship between plasma homocysteine (Hcy) and cognitive impairment so as to provide basis for dementia prevention.

METHODS: Subjects at high risk for stroke were selected from the Screening and Prevention Program of Stroke (organized by the Ministry of Health, from August to December, 2012) in Yanta area, Xi'an. Fasting blood was taken from cubital vein to measure Hcy. When Hcy>15 µmol/L was defined as hyperhomocysteinemia, Hcy in the range of 16-30 µ mol/L was considered mild, ≥ 31 µ mol/L as moderate-severe hyperhomocysteinemia. The cognitive function was evaluated by the Mini Mental State Examination (MMSE). MMSE grades under normal value were defined as cognitive impairment.

RESULTS: 393 subjects were randomly recruited, including 173 men (44.0%) and 220 women (56.0%). Number of cases with cognitive impairment was 70 (17.8% of the total subjects), with hyperhomocysteinemia was 220 (56.0% of the total subjects). The prevalence of cognitive impairment did not show significant difference with hyperhomocysteinemia or normal Hcy group (16.8% vs. 19.1%, P>0.05), neither with mild and moderate-severe hyperhomocysteinemia group (17.0% vs. 16.3% , P > 0.05). Results from Spearman correlation analysis indicated that there was no correlation between MMSE grades and Hcy (rs = -0.01, P = 0.85). Prevalence of cognitive impairment in the smoking group was higher than that in the non-smoking group (21.3% vs. 7.8%, P < 0.01), but higher in hypertension group than that in the normal blood pressure group (21.7% vs. 8.0%, P < 0.01). In the stroke group, prevalence of cognitive impairment was seen higher than that in the non-stroke group (25.3% vs. 15.4%, P < 0.05). Based on the results from Binary logistic regression, cognitive impairment appeared to be associated with the levels of education (OR = 0.90, 95% CI:0.81-0.98, P = 0.02), histories of hypertension (OR = 1.02, 95%CI:1.01-1.04, P = 0.01) and stroke(OR = 1.86, 95%CI:1.04-3.33, P = 0.04), but there was no correlation seen between Hcy and cognitive impairment (OR = 0.90, 95% CI:0.51-1.58, P = 0.71).

CONCLUSION: Plasma homocysteine did not seem a risk factor for cognitive impairment.