OCD

The main symptoms are having thoughts, images or impulses that keep coming into the mind and  are difficult to get rid of (called obsessions), and a strong feeling that the person must carry out or repeat  certain physical acts or mental processes (called compulsions). Common obsessions include being afraid  of dirt and germs, worrying that something is not safe (such as an electrical appliance), wanting to have things in a particular order, and thoughts and fears of harming someone else. Common compulsions  include excessive washing and cleaning, checking things repeatedly, keeping objects that other people  might throw away, and repeating acts, words or numbers in a pattern.