A large population-based study found an association of depression status and severity with decreased Vitamin D (serum 25(OH)D) levels and increased serum parathyroid hormone (PTH) levels in older individuals.
Levels of 25(OH)D were 14%lower in 169 persons with minor depression and 14% lower in 26 persons with major depressive disorder compared with levels in 1087 control individuals
Vitamin D is produced by your skin in response to exposure to ultraviolet radiation from natural sunlight.It is nearly impossible to get adequate amounts of vitamin D from your diet. Sunlight exposure is the only reliable way to generate vitamin D in your own body.It is impossible to generate too much vitamin D in your body from sunlight exposure: your body will self-regulate and only generate what it needs.
As people age, skin cannot synthesize vitamin D as efficiently and the kidney is less able to convert vitamin D to its active hormone form. Homebound individuals, people living in northern latitudes, women who wear long robes and head coverings for religious reasons, and people with occupations that prevent sun exposure are unlikely to obtain adequate vitamin D from sunlight.
Causes of vitamin D deficiency in the elderly are: less sun exposure as a result of decreased outdoor activity, different housing or clothing habits, and decreased vitamin intake.
The question remains whether the vitamin D deficiency is secondary to depression, or is depression the consequence of poor vitamin D status.
Low levels of Vitamin D could be involved in the pathogenesis of depression in several ways.
In human beings, the distribution of the vitamin D receptor seems to be similar to that in rodents, with the strongest staining occurring in the hypothalamus suggesting a role in neuroendocrine functioning. In earlier work,we found that the human hypothalamus is likely implicated in the pathogenesis of depression because a number of neuron types show altered levels of neuropeptides and corresponding gene expression in postmortem brain tissue from depressed patients compared with control subjects
Depression and depression severity, as measured with the Center for Epidemiologic Studies–Depression (CES-D) scale, is strongly associated with lower Vitamin D levels and higher PTH levels, even after adjustment for age, sex, BMI, smoking status, health status, level of physical activity, and level of urbanization. Longitudinal studies are needed to answer the question about cause and consequence of Vitamin D shortage and depression.
Hoogendijk, W.J. (2008). Depression Is Associated With Decreased 25-Hydroxyvitamin D and Increased Parathyroid Hormone Levels in Older Adults. Archives of General Psychiatry, 65(5), 508-512.