It is hard to communicate obsession – severe, clinical obsession, a true monopoly of thought. Here is the best description I have. Consider a computer, and the various windows and separate operations that the machine can run concurrently. As I write this, there is another window open in the background that updates my email, and a separate web browser that tracks football scores. When I choose, I can toggle between these windows, make them bigger or smaller, open and close others as I see fit. That is how the mind usually handles thoughts. It shares conscious concentration between tasks, while the subconscious changes the content of each window, or draws our attention among them. Obsession is a large window that cannot be made to shrink, move or close. Even when other tasks come to the front of the mind, the obsession window is there in the background. It acts as a constant drag on the battery and degrades the performance of other tasks. You can’t turn the machine off and on. Whenever you are awake, the window is there. And when you do manage to turn your attention elsewhere, you are aware of doing so. Soon enough, the obsession will reclaim the focus.
The obsessive thoughts of OCD tend to cluster around a limited number of themes. Obsessions of contamination with dirt and disease are the most frequent and feature in about a third of cases. Irrational fears of harm − did I lock the back door? Is the oven switched off? – are the next most common, and affect about a quarter of people with OCD. About one in 10 wrestles with an obsessive need for patterns and symmetry. Rarer, but still significant, are obsessions with the body and physical symptoms, religious and blasphemous thoughts, unwanted sexual thoughts and thoughts of carrying out acts of violence. It’s because obsessive thoughts are so often within these taboo and embarrassing subjects that so many people with OCD choose to hide them.
OCD is the fourth most common mental disorder after the big three − depression, substance abuse and anxiety. Its impact on quality of life has been judged more severe than diabetes. But people with OCD typically wait a decade or more before they seek help.