Intrusive thoughts of people with obsessive-compulsive disorder, or OCD are more frequent, last longer and create a need to act on the compulsion in order to neutralise their thoughts, finds a study.

It may be normal to have intrusive thoughts such as a random or inappropriate idea popping into people’s heads, or to feel compelled to double-check and triple-check that the front door is locked. Typically they go away and people go about our lives.