Katy Perry blames her childhood for her OCD.

The 28-year-old singer openly admitted she suffers from the Obsessive Compulsive Disorder, which can cause her to freak out if things are disturbed in her normal routine, but she's convinced the medical condition first flared up when she was a youngster.

Speaking to the new UK issue of ELLE magazine, she said: ''I have OCD tendencies. I do strange things with buttoning everything up and colour coordinating it, hanging it in a certain way. When things are out of control in your childhood, you find things to focus on. ''

The 'Wide Awake' hitmaker was brought up in a strict Christian household and previously revealed she struggles to read as she didn't ''go to school much'' due to her family constantly moving around the US when she was a child.

She said previously: ''I have a problem reading ... I wasn't going to great schools, because my parents didn't believe in public education. They wanted the education to be influenced by their religion, so I was going to these halfway education-slash-Christian schools that were like pop-up shop-style education.''