Some people have obsessive–compulsive disorder without compulsions. This is called "primarily obsessional OCD", or "pure-O". It is thought that up to half of all people with obsessive–compulsive disorder have primarily obsessional OCD. People with primarily obsessional OCD may have a third type of obsession; that is aggressive thoughts. People with aggressive thoughts may have obsessions about hurting or killing themselves or people around them. Instead of performing compulsions, people with primarily obsessional OCD may act out compulsions in their mind or avoid the things and places that cause the obsessions.