K.S.
I kind of have the opposite problem. I have OCD and BipolarII myself and struggle with getting my family to understand what all my disorders entail. My opinion is that 11 is definately old enough to understand, or at least begin to understand, what OCD is all about. In addition to having the disorders myself, I have worked with young adults with mental illnesses from depression to schizophrenia and it always helped for me to compare their illness to a physical ailment when it came to taking meds, etc. ie: Just like someone with heart disease, you take medication for your illness, or just like someone with diabetes, you may have some difficulties with work or school. There is such a stigma around mental illness still, I believe it's important to stress that it's a real illness with real symptoms and you might even explain to him what stigma means and what it is all about. Most importantly, teach him in a way that limits the amount of shame he may have around it. You might also get advice from the psychiatrist or therapist, if he sees one and search the internet for a kid's book on mental illness; I would think one would exist. This is an issue that's dear to my heart and I wish you good luck!