At times there's a biologic basis of the problem as infections or endocrine-system diseases, the hormonal shifts of the menstrual cycle, certain medications, exposure to toxic metals or chemical, an unbalanced diet. All of these can lead to depression. All of these can lead to depression. At the same time, we should think of our bodies, and the damage medicines can do to liver and kidneys. It is likely that, at one point or another, we will all experience a bout of depression.