By Amanda Gillies / 3news.co.nz

Stephen Fry is the funny guy with the serious illness. This month the British actor claimed bipolar may one day lead him to take his own life.

“You cannot conceive of such a thing as the future. Life is so black you cannot imagine a tomorrow,” he says.

Two months ago, movie star Catherine Zeta Jones announced she too was being treated for bipolar at a psychiatric hospital, but this is not an illness restricted to the rich and famous.

New Zealand Professor Peter Joyce says bipolar doesn't discriminate. Up to 3 percent of our population has it and symptoms can appear when patients are just 15 years old. They go on to experience extreme highs and lows, often triggered by stress.

“I'm aware of one person in my career who believed they were Jesus Christ, killed themselves but left a message saying they would be back in three days, believing they were going to be resurrected,” says Professor Dean Peter Joyce.

A study last year of more than 700,000 adults showed that those who scored top grades at school were four times more likely to develop bipolar disorder than those with average grades.

If the illness is well managed, people can lead successful happy lives, but securing the right medication and treatment isn't always easy.

“Getting the ongoing care is a real challenge. Too many mental health services have been set up for acute episodes and they don't provide the ongoing care, going private is outside the cost range for many people so there are real challenges to provide high quality on going care for people with bipolar disorder,” says Professor Joyce.

It's been acknowledged the behaviour of people going through extreme mania or depression is no longer in their control.