Buccal Cytome Biomarkers and Their Association with Plasma Folate, Vitamin B12 and Homocysteine in Alzheimer's Disease

Abstract

Background/Aims: Alzheimer's disease (AD) is an irreversible neurodegenerative disorder and is the commonest form of dementia. One aim of this study was to determine whether AD individuals have altered plasma folate, vitamin B12 and homocysteine (Hcy) levels compared to controls. The other aim was to investigate correlations between B vitamins and buccal biomarkers to test whether they are influenced by B vitamin status. Methods: Folate, vitamin B12 and Hcy were measured using ARCHITECT® and AxSYM® assays. Genomic stability was measured using the buccal micronucleus cytome assay. Results: The area under the receiver operating characteristic curve for AD basal cells was 0.96 (p < 0.0001), for karyorrhectic cells 0.88 (p < 0.0001) and for basal and karyorrhectic cells 0.91 (p < 0.0001). Hcy was significantly increased (p = 0.0003) compared to controls. Plasma vitamin B12 in controls showed a positive correlation with pyknosis (r = 0.5365, p = 0.004), karyolysis (r = 0.5447, p = 0.004) and condensed chromatin (r = 0.5238, p = 0.006). Plasma vitamin B12 in AD cases showed a positive correlation with micronuclei (r = 0.3552, p = 0.04) and basal cells (r = 0.3448, p = 0.04), whilst plasma Hcy showed a negative correlation with karyorrhectic cells (r =-0.4107, p = 0.01). Conclusions: Hcy was significantly increased in AD cases relative to controls. The lower frequency of basal cells and karyorrhectic cells observed in AD cases may be explained by lower vitamin B12 and higher Hcy levels, respectively.