The Savvy Psychologist explains the link between vitamin D deficiency and Alzheimer's Disease.
We already know that heavy smoking and drinking can increase the risk of developing Alzheimer’s, but a 2014 study found that a much more innocuous factor (or, more accurately, lack thereof) can also increase risk.
The researchers followed 1,685 senior citizens for approximately 5 and a half years and found that those who had low levels of vitamin D were 69% more likely to develop Alzheimer’s Disease, while those who had severe vitamin D deficiency had an increased risk of 122%.
See also: Understanding Vitamin D Deficiency
Now, the big asterisk is that this does not mean that low levels of vitamin D cause Alzheimer’s. There may be something else—some X factor—to which both vitamin D and Alzheimer’s are related. A mantra was pounded into my head during my research training: correlation does not imply causation.
For example, ice cream consumption and murder rates correlate, meaning that they rise and fall together. However, that doesn’t mean that a double scoop of rocky road will make you homicidal. Instead, the connection is summer—hot weather and late sunsets keep people out on the streets until later at night, which in turn increases both ice cream purchases and, unfortunately, the opportunity for violent crime.
So while the study makes it clear that vitamin D deficiency and Alzheimer’s go together, it’s still unclear exactly how.
In the meantime, vitamin D deficiency has been linked to a host of other health problems, including depression, so it can’t hurt to check your diet or ask your doctor for advice about how to balance the risks and benefits of sun exposure, a critical part of the body’s natural production of vitamin D.
Littlejohns, T.J., et al. (2014). Vitamin D and the risk of dementia and Alzheimer disease. Neurology, 83, 920-928.;