Low levels of vitamin D may increase risk of depression

Low levels of vitamin D have been linked to depression, according to UT Southwestern Medical Center psychiatrists working with the Cooper Center Longitudinal Study. It is believed to be the largest such investigation ever undertaken.

Low levels of vitamin D already are associated with a cavalcade of health woes from cardiovascular diseases to neurological ailments. This new study - published in Mayo Clinic Proceedings - helps clarify a debate that erupted after smaller studies produced conflicting results about the relationship between vitamin D and depression. Major depressive disorder affects nearly one in 10 adults in the U.S.

"Our findings suggest that screening for vitamin D levels in depressed patients - and perhaps screening for depression in people with low vitamin D levels - might be useful," said Dr. E. Sherwood Brown, professor of psychiatry and senior author of the study, done in conjunction with The Cooper Institute in Dallas. "But we don't have enough information yet to recommend going out and taking supplements."

UT Southwestern researchers examined the results of almost 12,600 participants from late 2006 to late 2010. Dr. Brown and colleagues from The Cooper Institute found that higher vitamin D levels were associated with a significantly decreased risk of current depression, particularly among people with a prior history of depression. Low vitamin D levels were associated with depressive symptoms, particularly those with a history of depression, so primary care patients with a history of depression may be an important target for assessing vitamin D levels. The study did not address whether increasing vitamin D levels reduced depressive symptoms.

The scientists have not determined the exact relationship - whether low vitamin D contributes to symptoms of depression, whether depression itself contributes to lower vitamin D levels, or chemically how that happens. But vitamin D may affect neurotransmitters, inflammatory markers and other factors, which could help explain the relationship with depression, said Dr. Brown, who leads the psychoneuroendocrine research program at UT Southwestern.