It is the single biggest cause of disability in the Western world but many sufferers say the stigma attached to it is worse than the illness itself, according to researchers.
While celebrity sufferers who speak out about their depression are hailed as heroes, ordinary citizens are shunned, taunted and abused.
An international study of more than 1,000 sufferers in 35 countries has found that three quarters said they had been ostracised by other people leading them to avoid relationships, applying for jobs and contacting friends.
Discrimination is leading many to put off seeking treatment with a subsequent worsening of their condition.
Drugs and psychotherapy can help 60-80 per cent of people with depression but only half get treatment and only 10 per cent receive treatment that is effective – at the right dose, for long enough and with the right kind of therapy.
The international study published in The Lancet found that levels of discrimination were similar to those for schizophrenia revealed in a similar study three years ago.
Professor Graham Thornicroft, head of health service and population research at the Institute of Psychiatry said: "We have a major problem here. Non-disclosure is an extra barrier – it means people don't seek treatment and don't get help."
While public confessions of depression by well known people including the tennis champion Serena Williams, the US actress Kir-sten Dunst and chat-show host Stephen Fry were increasing, abuse of sufferers was also widespread.
The Norwegian Prime Minister, Kjell Bondevik, attracted worldwide approval when he relinquished power for three weeks to his deputy in 1998 while he recovered from an episode of depression. He was subsequently re-elected.
In contrast, Professor Thornicroft described the case of a woman who had dog faeces posted through her door because neighbours wanted her out and another in which police halted an interview with a man whose flat had been burgled when they learnt that he had been in psychiatric hospital.
"Our findings show discrimination is widespread and almost certainly acts as a barrier to an active social life and having a fair chance to get and keep a job," he said.
The Government's Time to Change campaign launched in 2008 aimed at reducing discrimination against people with mental illness had proved to have had a "modest but significant" impact, he added.
In a separate study, researchers have found that the 2008 economic crash led to a deterioration in the mental health of men – but not women.
Anxiety and depression increased markedly among men in the three years following the crash, but women escaped largely unscathed.
Rising unemployment and falling income are not to blame, the researchers say. Instead, job insecurity is thought to be the cause.
Mental ill health among men rose from 13.7 per cent in 2008 to 16.4 per cent in 2009 before falling back to 15.5 per cent in 2010, according to the study published in the journal BMJ Open.
Men derive much of their social status from their occupation and are still the main wage earners in most families. They are becoming more mentally unstable because of the fear of losing their jobs in the recession.
The authors from the Social and Public Health Sciences Unit in Glas-gow, say that while women's mental health appeared to change little in the period it may have deteriorated since due to job cuts in the public sector.