Kerry Katona is to open up about her battle with depression in a new documentary.

The Atomic Kitten star has suffered from bipolar disorder for several years and in a Channel 5 show she revisits her difficult childhood to search for answers, reported the Daily Star.

Kerry, who is expecting her fifth child, said: "One in four people have mental health issues. I have four children and one on the way. You do the maths.

"I need to find out if this is hereditary or if my traumatic childhood is to blame."

In Kerry Katona: My Depression Diaries, the star looks at her early life, which included witnessing her mum suffer a violent attack at the hands of a boyfriend.

"From a young age I lived with aunties, uncles, stepdads and nanas," said the 33-year-old.

Kerry Katona: My Depression Diaries will air on Channel 5 later this year.