Low vitamin D may be associated with depression

Further research needed to determine whether changes in vitamin D, parathyroid hormone precede depression or follow it.

Older individuals with low serum vitamin D and high blood levels of parathyroid hormone may have a higher risk for depression, according to a recent report.

Researchers from the Netherlands used a population-based cohort study — Longitudinal Aging Study Amsterdam — of 1,282 residents aged 65 to 95 years to study the link between mood and blood levels. Depression was measured using participants self-reports.

Of the participants, 169 were diagnosed with minor depression, 26 with major depressive disorder and 1,087 with no depression. Participants had an average blood vitamin D level of 21 ng/mL and an average parathyroid hormone level of 3.6 pg/mL. Severity of depression was significantly associated with increased parathyroid hormone levels and decreased vitamin D levels (P=.03 and P=.008).

Those with major depressive disorder and minor depression had 14% lower vitamin D levels compared with those who were not depressed. Moreover, parathyroid hormone levels were 5% higher among participants with minor depression and 33% higher among those with major depressive disorder compared with non-depressed participants (P=.003).

“The clinical relevance of the present study is underscored by our finding that 38.8% of men and 56.9% of women in our community-based cohort had an insufficient vitamin D status,” the researchers wrote.

Treatment for low vitamin D and high parathyroid hormone levels may include higher dietary intake of vitamin D or calcium and increased sunlight exposure.

“Underlying causes of vitamin D deficiency and decreased vitamin intake may be secondary to depression, but depression may also be the consequence of poor vitamin D status,” they wrote. – by Katie Kalvaitis

It has been long known that hyperparathyroidism is associated with clinical depression. This is a disease that is actually often diagnosed by psychiatrists. As many as 55% of our parathyroid patients have been on some sort of antidepressant medication in the past year, oftentimes because they go to their doctor with multiple complaints that sound like depression: insomnia, memory loss, feeling down and depressed. As they are put on an antidepressant, eventually the workup turns out to be parathyroid related. This paper is interesting in that it is published in a psychiatry journal. I think it is important that psychiatrists understand the relationship between hyperparathyroidism and depression.

The significance here is the researchers approached it from a different standpoint and took patients with depression and looked at their parathyroid function. It is very different from other papers that took people with known parathyroid disease and looked at how many of them were depressed. The most common mistake we see is that people think low vitamin D is causing the high parathyroid hormone, when in the vast majority of cases it is the other way around – high parathyroid hormone is actually causing low vitamin D.

Only in the last few years, however, are we learning the relationship between vitamin D and parathyroid disease in parathyroid hormone. Whereas the primary goal of parathyroid hormone is to maintain serum calcium n the normal range, the sole purpose of vitamin D is to help maintain calcium homeostasis and facilitate absorption of calcium from our diet. We now know that people with severe vitamin D deficiency can show increases in their parathyroid hormone, but much more commonly people with high parathyroid hormone levels and primary hyperparathyroidism will show dramatic decreases in vitamin D.

– James Norman, MD, FACS, FACE

Parathyroid surgeon, Norman Parathyroid Surgery Clinic, Tampa

For more information:
Hoogendijk WJG, Lips P, Dik MG, et al. Depression is associated with decreased 25-hydroxyvitamin D and increased parathyroid hormone levels in older adults. Arch Gen Psychiatry. 2008;65:508-512.