For patients with a deficiency in vitamin B12, supplementation can improve their memory to some extent. However, there is currently no evidence that vitamin B12 can enhance memory in normal individuals. Many studies have shown that Alzheimer's patients have lower levels of vitamin B12 in their blood, and individuals with low vitamin B12 levels are at increased risk of developing Alzheimer's disease. Therefore, in theory, vitamin B12 may have some beneficial effects on Alzheimer's patients.