Research shows that people of lower socioeconomic status are more likely to develop a depressive illness than wealthier people. 

A study by a group of scientists from Harvard Medical School found that low-income people with depression are less likely to respond to treatment than those who have higher incomes.  The study was published in the medical journal, The Archives of General Psychiatry, and it analyzed 248 patients of varying income levels. 

It also found that people with lower incomes are more likely to be suicidal.

In the South African town of Kimberley, where diamonds are plentiful, but where wealth is scarce, there were so many cases of depression among teenagers that in one month, 150 attempted suicides were reported.

Elaine Van der Berg

Elaine Van der Berg works at a counseling service in Kimberley. "I think most of the crisis is financial issues. There are not a lot of work options in Kimberley. Also, recreation facilities and then mostly relationship problems."

Symptoms of depression include loss of interest, poor concentration and forgetfulness, lack of motivation, tiredness, irritability, poor sleep and changes in appetite.

One teen's friend was one of the many who committed suicide in Kimberley because of depression.  She says she feels it too.

Friend committed suicide

"I have considered suicide, very much, actually. But then I realized I was being selfish because I've got so many friends around me now that I look after."

Depression is a mental illness that affects millions of people worldwide, but only some are lucky enough to overcome it.   

Sixteen-year-old Jordan Walton is one of them.  She suffered from depression and had suicidal thoughts, until she started taking anti-depressant medication, a remedy that is widely used in America.

Jordan Walton

"Once I was on medication, things just started getting better," she said.

With prices ranging from $39 to $200 per month, not everyone can afford prescription medications.  For many people without insurance, it is a near-insurmountable cost.

Although the study tested only American subjects, researchers say its conclusions apply to people all over the world. 

And in developing countries, where depression affects about 15 percent of the population, as opposed to roughly 9 percent in the United States, there is often no access to doctors, hospitals or drugs, even if patients can afford them.