Elevated serum homocysteine level is not associated with serum C-reactive protein in patients with probable Alzheimer’s disease

Abstract

Elevated plasma homocysteine (Hcy) levels have been associated with Alzheimer's disease (AD) and cognitive impairment. Studies have shown that Hcy may have direct and indirect neurotoxicity effects. The aim of the study was to investigate serum Hcy concentration in patients with probable AD with age-matched controls and to determine whether there was an association between serum Hcy and C-reactive protein concentration in patients with probable AD. We also aimed to determine whether there was an association between serum tHcy concentration and cognitive impairment in patients with probable AD. Serum concentration of total Hcy was determined by the fluorescence polarization immunoassay on the AxSYM system, and serum C-reactive protein (CRP) concentration was determined by means of particle-enhanced immunonephelometry with the use of BN II analyzer. Cognitive impairment was tested by the MMSE score. Body mass index (BMI) was calculated for each subject included in the study. Age, systolic and diastolic blood pressure and BMI did not differ significantly between the two groups. Mean serum tHcy concentration in the control group of subjects was 12.60 mumol/L, while in patients with probable AD the mean serum tHcy concentration was significantly higher than 16.15 mumol/L (p < 0.01). A significant negative association between serum tHcy concentration and cognitive impairment tested by the MMSE score in patients with probable AD was determined (r = -0.61634; p < 0.001). Positive, although not significant correlation between CRP and serum tHcy concentrations in patients with AD, was observed. Increased tHcy concentration in patients with probable AD, and the established negative correlation between serum tHcy concentration and cognitive damage tested by MMSE score in the same group of patients, suggests the possible independent role of Hcy in the pathogenesis of AD and cognitive impairment associated with this disease.

Homocysteine, antioxidant vitamins and lipids as biomarkers of neurodegeneration in Alzheimer’s disease versus non-Alzheimer’s dementia

“…A significant negative relationship was found only between serum tHcy levels and MMSE scores in n-ADP. Other researchers have also shown a significant negative association between serum tHcy concentration and cognitive impairment tested by the MMSE score in patients with probable AD [15]. Although some studies found no association between plasma tHcy levels and cognitive impairment in patients with AD [16], in the presented study, the mean serum tHcy concentrations for AD and n-AD patients were elevated in comparison to upper reference limits for tHcy (20 µmol/l) in patients aged >65 years, and in comparison to control, but no statistically significant differences were noted.…”

Homocysteine and cognition: A systematic review of 111 studies

“…Overall, an inverse correlation was found between the MMSE scores and the plasma Hcy levels in cases (39)(40)(41)(42). Similarly, Kim and colleagues showed a significant negative relationship between the plasma Hcy levels and the scores of the Word List Memory and Constructional Recall (WLMCR) test in the AD group, after adjusting for several covariates.…”

Blood-Based Biomarkers of Alzheimer's Disease: Challenging but Feasible

“…Given that the association with AD may well be weaker than with cardiovascular disease, this emphasizes the gap between finding an association with disease and proof of utility as a biomarker. Nonetheless, CRP and tHcy may have independent effects on the risk of developing AD [51] and an elevation in CRP has been associated with AD, rate of progression of AD, MCI and Down’s syndrome [39,52–57]. However, other large longitudinal studies found that other general markers of inflammation, such as TNF-α but not CRP, were associated with risk of dementia or with brain volume [58,59] and others found an association between CRP and vascular dementia [60].…”