Preoperative Vitamin B12 and Folic Acid on POCD in Elderly Non-cardiac Surgical Patients

Vitamin B12 has long been suggested to have neural nutrient effect and widely used in clinical settings for patients with peripheral nerve injury as well as complementary medicine for patients with CNS disorders, including cognitive dysfunction. Evidences showed that, although no significant improvement in cognitive function was observed in healthy elderly after vitamin B12 supplementation, some studies suggested that patients with pre-existing CNS disorder may benefit from Vitamin B12. Post operational cognitive dysfunction (POCD) is severe, and long-lasting complication that affects as high as 53% of patients in high risk surgeries. Age is an independent risk factor for POCD. Researches have shown that serum vitamin B12 level decrease with age, and methylcobalamin (active form of Vitamin B12) content in the frontal cortex of aged patients are lower than that of younger patients. However, there are no report on effect of preemptive supplementation of vitamin B12 on POCD incidence. Therefore, the current research is aimed to explore the preoperative methylcobalamin supplementation (500 mg, 3/day for 7 days before surgery) on incidence of POCD. Folic acid supplementation is a common companion for vitamin B12 treatment in clinical settings because they are in the same methionine cycle, increase of one may result in deficiency of another. So we added 5 mg, 1/day of folic acid with methylcobalamin in the treatment group. This study will recruit patients more than 65 years old eligible for non-cardiac surgery. Patients who participate will take either vitamin B12 and folic acid supplementation or placebo for 7 days before surgery. Neuropsychological test battery (NPB) will be tested before intervention and at discharge for determination of Post operative cognitive dysfunction (POCD). Another group of non-surgical elderly participants will also be tested for NPB to account for learning effect in POCD diagnosis. The hypothesis is that preoperative vitamin B12 supplementation will reduce the incidence of POCD in elderly patients undergoing non-cardiac surgery.