Apolipoprotein E genotype modulates effects of vitamin B 12 and homocysteine on grey matter volume in A lzheimer's disease

Aims The aim of the present study was to investigate whether the effects of vitamin B 12 and homocysteine on brain volume are influenced by apolipoprotein E ( APOE ) genotype. We examined the effects in each subgroup ( APOE ε4 carriers and non‐carriers) of A lzheimer's disease ( AD ) patients and healthy normal controls. Methods Forty participants with AD and 20 healthy normal controls were recruited from memory impairment clinics at P usan N ational U niversity H ospital in K orea. All participants were APOE genotyped and underwent magnetic resonance imaging, including 3‐D volumetric images for grey matter ( GM ) volume. A multiple regression model integrated into statistical parametric mapping was used to see if there was any correlation between vitamin B 12 or homocysteine and GM volume in each subgroup ( APOE ε4 carriers and non‐carriers) of AD patients and healthy normal controls. Results There was a significant positive correlation between serum concentrations of vitamin B 12 and regional GM volume in APOE ε4 carriers with AD but not in non‐carriers. We also found that there was a significant negative correlation between serum concentrations of homocysteine and regional GM volume in APOE ε4 non‐carriers with AD but not in carriers ( P < 0.001, uncorrected for multiple comparisons; extent threshold = 100 voxel). Conclusion The present findings suggest that the effects of vitamin B 12 and homocysteine on GM volume might be influenced by APOE genotype.