Why a Well-Built Exposure Hierarchy Matters

In the behavioural treatment of obsessive-compulsive disorder (OCD), that is, in what we call exposure and response prevention (ERP), it’s important to start from a good hierarchy of compulsions. And what’s that? Basically, a list of all the compulsions (motor and mental) the client performs, rating how much anxiety or distress they would feel if they stopped doing each one.

Sometimes a client comes in and says: “Yes, but I don’t actually have any compulsions.” In practice, OCD without compulsions is very rare. It’s true that the DSM-5 allows a diagnosis with obsessions, compulsions or both, but when it seems there are only obsessions, mental compulsions (reviewing, mentally checking, neutralising one thought with another…) or behaviours such as avoidance or reassurance-seeking almost always turn up. If there really are none, it’s worth considering whether it’s a different kind of problem. Or: “Yes, but I only have this one compulsion, honestly, I don’t do anything else.” When this happens, even though the client believes they’re being sincere, the reality is that they usually aren’t well informed about what a compulsion is or, if they are, they’ve overlooked many of them because they consider them “normal”, “I’ve always done that” or “I hadn’t even noticed I was doing it”, to give a few examples. If this happens, you need to explore and explain to the client how their problem works so that you can identify the behaviours to be dropped. If this is done properly, the compulsions almost always come to light in the end.

I want to stress that when I talk about behaviours, I mean both types:

• Mental behaviours or compulsions (invisible to others): reasoning things out, mentally reviewing, mental counting…
• Motor behaviours or compulsions (visible to others): seeking reassurance from other people, cleaning, rearranging, repeating certain actions, avoiding…

A good hierarchy gives us our bearings and helps us gain perspective as treatment begins. It shows us where to start exposure, good exposure. I always recommend graded exposure, working from easier to harder: there’s no point heading for the eighth floor when we’re out of breath before reaching the second. And to know where to begin, it’s essential that the client guides us with a scale from 0 to 10 or 0 to 100, telling us how important each compulsion is. The more essential a compulsion is to the person, in other words the more distress the idea of dropping it causes, the later we’ll tackle it (as a general rule).

Generally speaking, until the compulsions at a certain level have been worked on and the gains have reasonably settled, it’s best not to go for the ones that cause the most anxiety, because the client may become overwhelmed and that can set back progress in therapy.

I believe graded exposure is best because that’s what most of the literature recommends, and my own experience confirms it’s the best way to do it. There are other, more intensive approaches but, except in the odd exceptional case where they might be considered (I’ve never used them), they aren’t the most appropriate. We have to remember that the client comes to us afraid, and none of us finds it pleasant or easy to face our greatest fears. Exposure based on a well-built, well-graded hierarchy increases the chances of success: by starting with “the easiest” steps, the client is more likely to succeed, and that success in turn reinforces them; seeing what they’ve achieved, they feel more motivated to keep going. Knocking down walls, one by one.

If we head for the fifth floor when we’re already struggling on the first, we increase the risk of sensitising the client through a bad experience. And if that happens, nobody wins. The last thing we want is to make the client more sensitised to the issue than they already are. We want them to feel stronger and more in control when faced with the feared stimuli or situations, not the other way round.

Sometimes the ratings in the hierarchy also turn out to be off: the client may think a situation will cause more or less anxiety than it actually does. If, during exposure to the feared stimulus, we realise they overestimated the distress of not doing the compulsion, that’s fine: they’ll move on more quickly to the next level of the hierarchy. If, on the other hand, we realise they underestimated how much the compulsion matters, we’ll re-rate the level of distress and work on it when its turn comes within the rest of the hierarchy. These things happen, because the idea a person has in theory is one thing and the reality once they get down to work is another. It isn’t a problem: if necessary, the hierarchy can be adjusted as we put it into practice.