Pure O: Why "Purely Obsessional" OCD Still Has Compulsions

Pure O, short for "purely obsessional", describes OCD in which there are no visible rituals - no washing, no checking, no arranging. The name is misleading. The compulsions have not disappeared; they have moved inside, where they are much harder to identify and easier to mistake for thinking. Pure O is not a separate diagnosis. It is OCD with mental compulsions.

This distinction is not pedantry. It decides whether treatment works, because ERP targets compulsions, and you cannot prevent a response you have not noticed.

Why the label caught on

Pure O became popular because it named something real. If your OCD presents as unrelenting intrusive thoughts about harm, sexuality, morality, or your relationship, and you have never washed your hands more than anyone else, the standard public picture of OCD does not describe you at all. Many people spend years assuming they cannot have OCD for exactly this reason.

So the term does useful work. It just should not be taken literally. The clinical research has been consistent for decades that mental rituals are common and that presentations with genuinely no compulsions at all are rare.

The mental compulsions to look for

This is the heart of it. Mental compulsions are repetitive mental acts done to reduce distress or prevent something feared. The common ones:

• Mental review. Going back over a conversation, a memory, or an event to establish what happened. Central to real-event OCD.
• Rumination. Working the problem. Trying to think your way to a conclusion that will settle it.
• Self-reassurance. Silently telling yourself that you would never, that you are a good person, that it is just OCD.
• Mental arguing. Debating the thought. Marshalling evidence against it.
• Checking your feelings. Scanning your body or your emotional reaction for evidence about what you really want. The groinal check in sexual orientation OCD, the “do I still feel love” check in ROCD.
• Neutralising. Replacing a bad image with a good one, saying a phrase, counting, praying to cancel a thought.
• Mental checking of memory. Trying to summon a clear enough recollection to be sure.

If you recognise several of these, the “purely” part of Pure O does not apply to you, and that is good news. It means there is something to prevent.

Obsession or compulsion? The test that works

The hardest skill in treating Pure O is telling the obsession from the compulsion, because both are thoughts. The distinction is not content. It is direction.

• An obsession arrives. It is involuntary, unwanted, and it increases distress.
• A compulsion is performed. It is something you do, deliberately even if habitually, and it is aimed at reducing distress.

The practical question: am I having this thought, or am I doing it?

“What if I hurt someone” arriving unbidden is the obsession. The forty minutes that follow, spent carefully establishing that you would not, is the compulsion. The first is what you expose yourself to. The second is what you prevent.

A useful second check is the intent. Rumination always has a goal, even when it does not feel like it: to reach certainty, to feel resolved, to be sure. Notice the goal and you have found the ritual.

Why the compulsions are so hard to give up

Mental compulsions have three advantages over physical ones, from the OCD’s point of view.

They are invisible. Nobody can see you doing them, so nobody intervenes, and there is no external friction at all.

They are always available. You cannot leave the house without your mind. There is no equivalent of putting the knives away.

They pass for thinking. Rumination feels like problem solving, and our culture is generally in favour of problem solving. It takes a real shift to accept that in this specific case, careful sustained thought about the problem is the problem.

How ERP is adapted for mental compulsions

The structure is the same as any ERP, but the emphasis shifts.

• Imaginal exposure does most of the work. You write out the feared scenario, or record it, and deliberately expose yourself to it repeatedly without neutralising. Since the trigger is internal, the exposure has to be too.
• Detection training comes first. Before you can prevent the ritual, you need to catch it starting. Many people begin by simply tallying occurrences for a week, making no attempt to stop. You cannot prevent what you cannot see.
• Disengagement, not suppression. Response prevention here means noticing that you have begun ruminating and declining to continue - deliberately leaving the question open. It does not mean pushing the thought away, which is its own compulsion and tends to backfire.
• Uncertainty statements are exposures. “Maybe it is true, I cannot know” is not a coping phrase to be said until you feel better. It is meant to leave you uncomfortable. If it comforts you, it has become reassurance.
• Everything mental is on the hierarchy. Silent reassurance, checking your feelings, praying to cancel a thought. If it is done to make the distress stop, it goes on the list.

What this looks like from the inside

For about six years I would have told you, sincerely, that I had no compulsions. I was proud of it in a strange way. Whatever was wrong with me, at least I was not doing anything embarrassing.

What I was actually doing was spending two to three hours of every day mentally re-examining a set of about four events, and I did not count that as behaviour because it happened in the same place my thinking happens. It was just what my head did. It felt like being a thoughtful person with an unusually detailed memory.

The week my therapist asked me to tally it was genuinely shocking. Not the content - the volume. I had been running a full-time ritual and filing it under personality.

Catching it early was the hard part, and it stayed hard for months. Rumination does not announce itself. It starts as one reasonable-sounding question and you are twenty minutes in before you notice you are not thinking, you are checking.

Sources

• International OCD Foundation: Mental compulsions and “Pure O”
• Williams, M. T., et al. (2011). Myth of the pure obsessional type in obsessive-compulsive disorder. Depression and Anxiety, 28(6), 495-500.
• Rachman, S., & de Silva, P. (1978). Abnormal and normal obsessions. Behaviour Research and Therapy, 16(4), 233-248.
• Salkovskis, P. M. (1999). Understanding and treating obsessive-compulsive disorder. Behaviour Research and Therapy, 37, S29-S52.