An Enigmatic Mental Illness With Exact Cause Still Not Known

"When all is said and done, they are stranger to me than the birds in my garden," said Swiss psychiatrist Eugen Bleuler of his patients with schizophrenia.

- Chong Siow Ann

It was Dr Bleuler who, after years of socializing with his patients and studying them at close quarters, coined the term "schizophrenia" in 1911.

More than a century later, schizophrenia remains arguably the most unusual and enigmatic of all the mental illnesses. We don't have a definitive cure, largely because we still don't know its exact cause.

But we know that genes matter – more than a hundred independent sites scattered across the genome have been associated with schizophrenia, though each confers only a very small risk.

Adverse childhood experiences may matter, along with a host of other implicated factors like birth complications, urban living, stress of migration and demoralization from racial discrimination. But in a large number of cases, there are no discernible risk factors.

In my long practice, I have seen hundreds of patients with schizophrenia, and in almost every case, I have been asked by bewildered patients and families why they have ended up with this illness.

Often, the only answers are words that are thoroughly unscientific (and that I sometimes can't bear to say) – luck, chance, destiny.

Schizophrenia is the most serious form of psychosis, which is defined as a major mental disorder in which the individual's ability to think, respond emotionally, interpret reality, and behave appropriately is impaired to the extent that it interferes grossly with his capacity to meet the ordinary demands of life.

Globally, somewhere between 0.5 per cent and 1 per cent of the world's population – men and women of all ethnic and cultural groups – will be stricken with schizophrenia in their lifetimes. It is not the most common psychiatric condition; depression and anxiety disorders are the most common.

But various analyses by different bodies, including the World Health Organization, have consistently shown that it is schizophrenia that has a disproportionately high social cost.