Association of vitamin B12 deficiency in a dementia cohort with hippocampal atrophy on MRI

• This analysis consists of 567 participants revealed that vitamin B12 deficiency, not folate or vitamin B1 deficiency was associated with hippocampal atrophy detected by MRI-VSRAD analysis. • Vitamin B12 deficiency was associated with hyperhomocysteinemia. • Clear correlations were observed between hippocampal atrophy and vitamin B12 value. Vitamin deficiencies have been reported to cause brain atrophy. Hippocampal atrophy has been well reported in patients with dementia including Alzheimer’s disease. To investigate the association between hippocampal atrophy and vitamin deficiency Cross sectional study Three sites in one country Overall, 567 patients who visited an outpatient dementia clinic and underwent MRI-VSRAD (Voxel-Based Specific RegionalAnalysis System for Alzheimer's Disease) were included in this study. Patients with a hippocampal atrophy Z-score of < 2 were classified as normal ( n = 323), and those with a Z-score of ≥ 2 were diagnosed with hippocampal atrophy ( n = 244). Vitamin B 12 , folic acid, vitamin B 1 , homocysteine, HbA1c, and creatinine levels were measured and their association with hippocampal atrophy was assessed. Age, MMSE (Mini Mental State Examination), and hippocampal atrophy were also evaluated. In the hippocampal atrophy group, the frequency of vitamin B 12 deficiency was higher ( p < 0.022), MMSE score was lower ( p < 0.0001), and age was higher ( p < 0.0001) than that in the normal group (Mann-Whitney U test ). Patients with vitamin B 12 deficiency (odds ratio, 3.46) and low MMSE score (odds ratio, 2.24) had an increased risk of hippocampal atrophy. Vitamin B 12 deficiency was associated with hippocampal atrophy detected by VSRAD analysis. Therefore, early vitamin B 12 supplementation should be considered in patients with deficiencies to reduce dementia risk.