Older adults with low blood levels of vitamin D and high blood levels of a hormone secreted by the parathyroid glands may have a higher risk of depression, according to a report in the May issue of Archives of General Psychiatry.
About 13 percent of older individuals have symptoms of depression, and other researchers have speculated that vitamin D may be linked to depression and other psychiatric illnesses, according to background information in the article. "Underlying causes of vitamin D deficiency such as less sun exposure as a result of decreased outdoor activity, different housing or clothing habits and decreased vitamin intake may be secondary to depression, but depression may also be the consequence of poor vitamin D status," the authors write. "Moreover, poor vitamin D status causes an increase in serum parathyroid hormone levels." Overactive parathyroid glands are frequently accompanied by symptoms of depression that disappear after treatment of the condition.
Witte J. G. Hoogendijk, M.D., Ph.D., and colleagues at VU University Medical Center, Vrije Universiteit Amsterdam, the Netherlands, measured blood levels of vitamin D and parathyroid hormone and assessed symptoms of depression among 1,282 community residents age 65 to 95. Of those individuals, 26 had a diagnosis of major depressive disorder, 169 had minor depression and 1,087 were not depressed. The average blood vitamin D level was 21 nanograms per milliliter and the average parathyroid hormone level was 3.6 picograms per milliliter.