The number of Americans suffering from depression is on the rise according to results from a survey showing that nearly 10% of Americans suffer from clinical depression up from the 2001-2002 figure of 6.6%.

The survey conducted by the Centers for Disease Control and Prevention polled from 2006-2008 had 235,000 adult participants from 45 states, the U.S. Virgin Islands, Puerto Rico and Washington, D.C.

Study results showed approximately a third of depressed Americans have a severe form of mental disorder which is linked to unemployment. Contrasting sharply from the unemployed participants, only two percent of people with jobs suffered from major depression.

The study found depressive disorders to be more common among persons with chronic conditions including; obesity, cardiovascular disease, diabetes, asthma, arthritis, and cancer. Depression is also more prevalent in people with unhealthy behaviors including smoking, lack of exercise and drinking.

Education was found to be the second biggest contributing factor to depression. The study found 6.7 per cent of depressed people had less than a high school diploma, compared to four percent of high school graduates and only 2.5 per cent of people who had spent one or two years at university.

The rates of depression varied across the US with Mississippi having the highest rate at 15% and North Dakota with the lowest at 5%.

Women and young people were found to more likely to become depressed.