Mental illnesses are medical conditions that disrupt a person's thinking, feeling, mood, ability to relate to others and daily functioning.
That definition comes from the National Alliance on Mental Illness, the largest grassroots health organization in the United States that is dedicated to people affected by mental illness.
Mental illnesses include depression, schizophrenia, bipolar disorder and a host of other disorders, and severity can vary widely from person to person. Consequences of such illnesses involve difficulties in sustaining personal relationships and carrying on daily lives, and sometimes self-destructive behavior, even suicide.
Depression also is a major component of other mental illnesses. The World Health Organization has reported that by 2020, depression will be the second most prevalent cause of disability in the world, next to only heart disease.
According to the China Association of Mental Health, more than 260 million people in China suffer from depression, and more than 60 per cent of them have never been to even a general hospital seeking information or treatment.
Most don't know they have depression. Only 10 per cent of depression patients receive effective medical treatment, the association said.
Mental illness is not a character flaw that can be resolved through will power. Nor is it confined to adults.
In Beijing, the association said, 83 children in every 1,000 had mental illness in 1984, but the rate had tripled by 2002. Of the children who were diagnosed, 70 per cent had hyperactive or transient disorder.
As the only children in their families, one Beijing psychiatrist said, today's youngsters generally have been overly pampered, which weakens their social adaptability. They also have heavier study burdens than children before them.
According to the Asian Society for Child & Adolescent Psychiatry Allied Professions, 30 million children in China have mental problems but fewer than 300 doctors specialize in treating them.