Mental illness will be the second biggest cause of death and disability by 2020, according to the World Health Organisation. It has released global figures on mental health to help launch a campaign aimed at removing the stigma from mental illness.

The biggest killers in the world today are acute lower respiratory illnesses, but the infection rate of these diseases is expected to tail off in the next few years, the WHO says. Ischaemic heart disease, the sixth leading cause of death today, will be the world's biggest killer in two decades' time, followed by mental disorders.

Mental illnesses, from epilepsy to depression, currently affect over 400 million people around the world. This group includes 45 million people with schizophrenia.

America and Japan experience the highest levels of depression, but research has shown significant levels of depression in Brazil, Zimbabwe and India. Over 1 million people now die through suicide each year and the ten countries with the highest suicide rates are all former Soviet states.

"We can expect a decrease in suicides if we are properly treating depressed people", according to the WHO. "There is a common myth that mental health problems are those of rich, industrialised countries - a luxury. But mental and neurological problems are equally important in rich and poor countries".