Patients with obsessive-compulsive disorder often suffer in silence

A year ago, Nicky's life was very different. Scared, he would stay in bed all day with a blanket over his head, leaving only to wash his hands or take a shower, which could last for more than an hour. "I'd cover myself with blankets and spend the day in bed. It felt safe," he says.

"I could spend two hours in the shower - I felt so bad about it, that I contemplated suicide."

The 24-year-old Hongkonger agreed to be interviewed on condition his last name was not used because of the stigma attached to people with mental health problems. Last year, he was diagnosed with obsessive-compulsive disorder (OCD).

Obsessive-compulsive disorder is a type of anxiety disorder where patients obsess over certain thoughts. Sufferers perform rituals such as washing their hands over and over again, even if they know their behaviour is irrational.

There's no definitive explanation for what causes obsessive-compulsive disorder, although research connects it to abnormal activity in some areas of the brain, says Lee Wing-king, a psychiatrist and consultant for Kwai Chung Hospital in the New Territories.

There are no statistics on the prevalence of OCD in Hong Kong. In a February 2009 monthly digest, the Census and Statistics Department estimated that 1.3 per cent of the total population, around 86,000 people, suffer from a mood disorder or mental illness.