Bae JB, Han JW, Song J, et al. - This study was undertaken to investigate if hypohomocysteinemia, like hyperhomocysteinemia, could increase the risk of dementia and Alzheimer's disease (AD) in a large population-based cohort of older adults. Researchers conducted a prospective cohort study that followed 2,655 randomly sampled, community-dwelling, non-demented individuals aged 60 years or older from 2010 to 2018. They assessed baseline serum total homocysteine (tHcy) levels and examined the effect of serum tHcy on the risks of dementia and AD using Cox proportional hazards models. Dementia and AD developed in 85 and 64 participants, respectively during the follow-up period (mean = 5.4 years, SD = 0.9). The results showed that in older adults, not only hyperhomocysteinemia but also hypohomocysteinemia considerably increased the risk of dementia and AD. The findings suggested that the risk of dementia that results from overuse or misuse of vitamin supplements should be acknowledged and homocysteine-lowering health policies should be tailored to consider dementia risks that are associated with hypohomocysteinemia.