Incidence of prescription vitamin B12 use in relation to diagnosis of Alzheimer’s disease among community-dwelling persons

Abstract

Aims: To evaluate the incidence of described purchases of vitamin B12 in community-dwelling persons with and without Alzheimer’s disease (AD) from 9 years before to 5 years after the diagnosis. Subject and methods: We utilized register-based data from the Finnish nationwide MEDALZ (Medication use and Alzheimer’s disease) cohort, including all AD cases who received a diagnosis in 2005–2011 (N = 70,718) and their age-, gender-, and region of residence-matched comparison persons without AD. Information on vitamin B12 use during 1995–2012 was collected from the Prescription Register. Results: During the follow-up, 5669 persons (8.2%) with AD and 3408 comparison persons (4.9%) initiated vitamin B12 use. The incidence rate of vitamin B12 use was significantly higher among persons with AD, beginning from one and a half years before the diagnosis and remained higher until 3 years after the diagnosis. The difference between the incidence rates was highest at the time of diagnosis (incidence rate ratio = 4.43, 95% confidence interval 3.82–5.14). The incidence started to increase also in persons without AD approximately 4 years before the diagnosis, remaining higher during the follow-up. Conclusions: The incidence of vitamin B12 use was considerably higher among persons with AD than in persons without AD around the time of AD diagnosis. On the other hand, the incidence of vitamin B12 use increased during the follow-up also in persons without AD. Regular checks of vitamin B12 levels among older people and earlier treatment of deficiency might reduce the disability related to vitamin B12 deficiency.