Vitamin D and Dementia
Vitamin D Deficiency Increases Your Risk of Alzheimer's
Vitamin D has long been associated with increased risk of developing brain disorders. The vitamin has gotten a lot of attention lately in relation to depression, multiple sclerosis, alzheimer’s, and dementia. Sometimes the broad range of vitamin D’s effects makes people skeptical of the actual effectiveness of vitamin D. People who do know about vitamin D often still associate it only with bone health. I can’t blame them; only recently have researchers begun to really look at vitamin D receptors outside of the parathyroid-vitamin D axis.
The truth is, vitamin D regulates many cellular processes beyond its use as a hormone for calcium absorption. And we’ve found that some of those cellular processes are directly related to Alzheimer’s disease.
As far back as the early ’90s, a relationship between concentrations of the vitamin D hormone in the brain and alzheimer’s was noted.1
In 2008, a study showed that higher blood serum levels of vitamin D3 correlated with better cognitive performance in Alzheimer’s patients.2
A study in 2009 from UCLA showed that vitamin D stimulated immune cells responsible for “clean up” to pick up more amyloid beta peptides. Plaques formed by these peptides are considered a main cause of the neural damage in alzheimer’s disease.3
Studies have shown that people with genetically defective vitamin D receptors (that is, people who have particular gene mutations which cause their vitamin D receptors to be less effective) are significantly more likely to have alzheimer’s.4,5
Additionally, a study looking at cortical neurons in the presence of amyloid beta and vitamin D found an interesting relationship between the two. Amyloid beta was observed to activate cell toxicity and cell death. Administration of vitamin D had a protective effect, counterbalancing those negative effects of amyloid beta.6
So it wasn’t all that surprising last year when a study published in the journal Neurology showed that vitamin D deficiency significantly increased the risk of dementia and Alzheimer’s disease in subjects7
That study has received a decent amount of attention in the media, and for good reason. The study found that subjects who had “deficient” blood serum vitamin D levels (between 25nmol/L and 50nmol/L) were over 50% more likely to develop dementia than subjects with sufficient levels of vitamin D. Subjects with “severely deficient” blood serum vitamin D levels (less than 25nmol/L) were OVER twice as likely to develop dementia than subjects with sufficient levels of vitamin D. The numbers for Alzheimer’s disease in particular were similar. Alzheimer’s disease is the most common cause of dementia.
The problem is, somewhere around 25% of the US population falls into that “deficient” category, according to NHANES data.8 Somewhere around 5% of the US population falls into the “severely deficient” category. That’s a lot of people.
Something that’s worth noting, if all of this information has swayed you into raising your vitamin D levels — many of the studies mentioned above looked at vitamin D3. Those important vitamin D receptors? They’re 1,25[OH]D3 receptors. All the research available suggests that vitamin D2 is not as effective as vitamin D3; receptors for vitamin D are for vitamin D3, not vitamin D2. Those receptors will typically accept vitamin D2, but at slower rates, making them less effective. Many doctors are still prescribing vitamin D2, in large part because there was no prescription vitamin D3 until relatively recently. You may want to ask specifically for vitamin D3.
1: Sutherland, M. K., Somerville, M. J., Yoong, L. K., Bergeron, C., Haussler, M. R., & McLachlan, D. R. C. (1992). Reduction of vitamin D hormone receptor mRNA levels in Alzheimer as compared to Huntington hippocampus: correlation with calbindin-28k mRNA levels. Molecular brain research, 13(3), 239-250.
2: Oudshoorn, C., Mattace-Raso, F. U. S., van der Velde, N., Colin, E. M., & Van der Cammen, T. J. M. (2008). Higher serum vitamin D3 levels are associated with better cognitive test performance in patients with Alzheimer’s disease. Dementia and geriatric cognitive disorders, 25(6), 539-543.
4: Gezen-Ak, D., Dursun, E., Ertan, T., Hanagasi, H., Gürvit, H., Emre, M., … & Yilmazer, S. (2007). Association between vitamin D receptor gene polymorphism and Alzheimer’s disease. The Tohoku journal of experimental medicine, 212(3), 275-282.
5: Lehmann, D. J., Refsum, H., Warden, D. R., Medway, C., Wilcock, G. K., & Smith, A. D. (2011). The vitamin D receptor gene is associated with Alzheimer’s disease. Neuroscience letters, 504(2), 79-82. Chicago
6: Dursun, E., Gezen-Ak, D., & Yilmazer, S. (2011). A Novel Perspective for Alzheimer’s Disease: Vitamin D Receptor Suppression by Amyloid-ß and Preventing the Amyloid-ß Induced Alterations by Vitamin D in Cortical Neurons. J Alzheimers Dis, 23, 207-219.
7: Littlejohns, T. J., Henley, W. E., Lang, I. A., Annweiler, C., Beauchet, O., Chaves, P. H., … & Llewellyn, D. J. (2014). Vitamin D and the risk of dementia and Alzheimer disease. Neurology, 83(10), 920-928.