A recent animal study published in Psychoneuroendocrinology found that depression caused by chronic unpredictable mild stress increases the metabolism and concentration of vitamin D in the hippocampus and cardiac muscle.
Chronic unpredictable mild stress (CUMS) is an accepted model of animal depression. In rats, chronic stress leads to depressive behavior, abnormal cardiac function, and exaggerated reactivity to stressors. In humans, the precipitation of depressive episodes have been linked to stressful life events. There is a positive association between depression and cardiac morbidity and mortality, and depression is recognized as a risk factor for cardiovascular disease (CVD). Individuals with major depression have four times the risk of a heart attack than the general population.