Cognitive and psychiatric effects of vitamin B12 replacement in dementia with low serum B12 levels: a nursing home study

BACKGROUND: The aim of this study is to determine whether B12 replacement would ameliorate cognitive and psychiatric symptoms in elderly subjects with dementia and low serum B12 levels. METHODS: A test group (n = 28) of nursing home residents with low serum B12 levels (<250 pg/mL) and a matched comparison group (n = 28) with normal serum B12 levels (>300 pg/mL) were evaluated by blinded raters while the test group received intramuscular (IM) B12 replacement therapy. All subjects were assessed at baseline, 8 weeks, and 16 weeks with the Dementia Rating Scale, Brief Psychiatric Rating Scale, and Geriatric Depression Scale. RESULTS: Although B12 replacement produced significant improvement in hematologic and metabolic parameters, it yielded no significant effect on cognitive or psychiatric variables. A few subjects evidenced notable individual treatment responses; however, these were not statistically more frequent than in the normal B12 group. CONCLUSIONS: These results suggest that B12 replacement is unlikely to benefit cognitive or psychiatric symptoms in the vast majority of elderly dementia patients with low serum B12 levels.