Researchers from Southwestern Medical Center have found that a lack of vitamin D is associated with the development of depression.
Depression currently affects one in 10 American people at some point in their lives, a problem that should not be underestimated as suicide is the tenth leading cause of death and amounted to 11.3 deaths per 100,000.
In 2007, 34,598 people lost their lives to suicide. For every death, National Institute of Mental Health estimates there are another 11 suicide attempts.
After screening 12,600 people for vitamin deficiency between 2006-2010, the researchers found that those with higher levels of vitamin D had less risk of depression, even in those people who had a previous history of depression. They also found that low vitamin D levels were associated with symptoms of depression.
They aren’t sure whether it is the depression that is causing the low vitamin D levels or whether the low vitamin D levels cause the depression, but said that a lack of the vitamin can lead to inflammation and that in turn can affect the neurotransmitters of the brain.
How Does Inflammation Cause Depression?
The National Institute for Mental Health says that when a person is infected with a virus or bacteria, it stimulates their immune system to produce cytokines. The cytokines trigger the immune system to defend the person and help them fight the infection.
However, cytokines also trigger inflammation and this inflammation can cause changes in behavior, withdrawal and fatigue. Cytokines are known to cause depression in people with physical illnesses even when they have no history of mental illness.
In animal tests, scientists used a BCG vaccine to induce chronic inflammation. They infected mice with high doses of BCG to persistently activate the immune system. Once the mice recovered from their illness, they developed depressive-like behavior.
The same effect is seen in humans when they receive cytokine interferon a for the treatment of cancer. One-third of these patients go on to develop major depression.