We thank Dr. Beale for the interesting comment on our article. [1] We agree that Vitamin D is a possible confounder. However, we did not detect a modifying effect of Vtiamin D in our study. Even if existing data are not sufficient to conclude that Vitamin D reduces dementia risk, an association was found between low plasma 25-hydroxy vitamin D and an increased risk of Alzheimer disease and vascular dementia. [2] Therefore, Vitamin D supplementation might even decrease the risk of dementia. As noted in our paper, the study was observational. Thus, true cause and effect cannot be proven.
1. Kern J, Kern S, Blennow K, et al. Calcium supplementation and risk of dementia in women with cerebrovascular disease. Neurology 2016;87:1674-1680.
2. Afzal S, Bojesen SE, Nordestgaard BG. Reduced 25-hydroxyvitamin D and risk of Alzheimer's disease and vascular dementia. Alzheimers Dement 2014;10:296-302.
For disclosures, please contact the editorial office at journal@neurology.org.
We thank Dr. Beale for the interesting comment on our article. [1] We agree that Vitamin D is a possible confounder. However, we did not detect a modifying effect of Vtiamin D in our study. Even if existing data are not sufficient to conclude that Vitamin D reduces dementia risk, an association was found between low plasma 25-hydroxy vitamin D and an increased risk of Alzheimer disease and vascular dementia. [2] Therefore, Vitamin D supplementation might even decrease the risk of dementia. As noted in our paper, the study was observational. Thus, true cause and effect cannot be proven.
1. Kern J, Kern S, Blennow K, et al. Calcium supplementation and risk of dementia in women with cerebrovascular disease. Neurology 2016;87:1674-1680.
2. Afzal S, Bojesen SE, Nordestgaard BG. Reduced 25-hydroxyvitamin D and risk of Alzheimer's disease and vascular dementia. Alzheimers Dement 2014;10:296-302.
For disclosures, please contact the editorial office at journal@neurology.org.