Obsessive Compulsive Disorder can be crippling to the sufferer, whether they have compulsions or not. As a child I had classic OCD (bad image in head repeatedly, then I had to repeatedly pray; or count steps until it "felt right").
Now it's mostly Pure O (Pure Obsessions).
For instance, one thing I keep thinking is that other people can't see me. Intellectually, I know this is not true, but the thought causes extreme anxiety. Most recently traffic patterns and occupation patterns are bothering me. I'll see a busy street and wonder how in the hell could so many people be out and about. Then I try to think where they were coming from, going to, etc. while also thinking about what their occupation is. And I wonder how could there be so many occupations. It's stupid, I have a college degree and am no village idiot. But my mind does not want to grasp it. It just doesn't click.
I could go on and on but I'm at Micky D's at the moment and need to get back on the road to DC.
Imagine OCD and Depersonalization as bed mates - that's me.