Research appearing in the Journal of Neurological Sciences (2009; 284(1-2): 144-8) found that in 102 patients with Alzheimer’s disease, 7% were found to be B12 deficient (with deficiency defined as serum B12 being less than 350 ng/L) upon testing. In follow-up testing two years later, 22% were found to be B12 deficient. The authors of the study concluded that testing for B12 after may help to prevent the neurologic damage of B12 deficiency and help improve quality of life.