What causes OCD?
Up until the 1970s, most mental health professionals looked at OCD through the lens of psychoanalysis, which regarded obsessions as irruptions of deep, instinctive, and principally sexual urges, and compulsions as attempts to control these urges. Persuading a person with OCD to abandon their compulsions was seen as a sure-fire means to propel the individual into psychosis (the technical term for insanity).
That consensus began to change with the ground-breaking work of behavioural psychologists such as Stanley Rachman. The behaviourists argued that obsessions arise from conditioned anxiety. A person who learns to fear contamination, for instance, may become anxious at the sight or mere thought of dirt. When they wash themselves, their anxiety quickly subsides. And because washing makes them feel so much better, they’ll do it again the next time they feel anxious (this is an example of positive reinforcement).
But Rachman and colleagues demonstrated that it isn’t necessary to use compulsions to reduce the anxiety triggered by obsessions. In what’s known as exposure and response prevention treatment, patients are taught to refrain from reacting compulsively. What they discover is that their anxiety will decrease all by itself. The debilitating cycle of obsession and compulsion is broken, and lasting improvement in OCD symptoms usually follows.
Cognitive theories of OCD have built on the insights of behaviourist approaches. The main model has been formulated by Paul Salkovskis, who argues that what distinguishes the person with OCD is not unpleasant, intrusive impulses — as we’ve seen, almost everyone experiences those — but rather the way they interpret such impulses.
At the core of that interpretation is the idea that, as Salkovskis puts it, ’the person may be, may have been, or may come to be, responsible for harm or its prevention’ (either to oneself or others). So someone with OCD may believe that, if they don’t constantly wash themselves or clean their home, they or their loved ones will develop a fatal illness. A person disturbed by ideas of violence may believe that such thoughts prove they are a danger to others. And an individual who sees an image of their home in flames may fear that this is what will happen unless they repeatedly check that electrical appliances have been switched off. Salkovskis argues that these feelings of responsibility are generally the result of early life experiences — for example, the attitudes with which we were brought up.
Understandably, such feelings can cause great anxiety. The person with OCD tries to rid themselves of that anxiety (and prevent the disaster they fear) through their compulsions. Unfortunately, although a compulsion may bring short-term relief, in the long run it only serves to maintain and indeed increase the anxiety. There are several reasons for this:
• The compulsion draws the person’s attention to the obsessive thought, making it more likely to recur.
• Compulsions are a form of safety behaviour. As we’ve seen, safety behaviours prevent us from discovering that our anxiety is exaggerated: someone who avoids physical contact with other people because they’re afraid of contamination is unable to learn that you can’t contract an illness by shaking hands.
• Compulsions frequently involve unrealistic targets. Regardless of the precautions we take, we can never be certain that an accident won’t occur. No matter how long we spend washing and cleaning, absolute spotlessness is sure to elude us. The desire for cast-iron certainty leaves the person with OCD feeling that they could always do more — thereby fuelling their anxiety.
• Many compulsions are inherently counterproductive. For example, people with OCD often try to suppress their obsessions. But trying not to think about something can make it more likely that you’ll do so, not less. (You can give this a go: try not to think about white bears.) And there’s evidence that people with OCD are less able to suppress thoughts than other people.
• Repeated checking is a common feature of OCD. Yet checking doesn’t bring certainty: in fact, the more a person (even someone without psychological problems) checks something, the less sure they become. This is because repeated checking reduces the vividness of our memory, though not its accuracy. And because the memory seems less vivid, we distrust it — and thus check again.
The cognitive behavioural therapy developed by Salkovskis and colleagues teaches the person with OCD to change the way they interpret their impulsive thoughts — to regard them as normal and inconsequential, rather than doom-laden reminders of personal responsibility — and to abandon the compulsions that fuel their anxiety.
Neurologically, OCD is distinct from the other anxiety disorders. The latter, as we saw in Chapter 2, are thought to involve problems in the amygdala, frontal lobes, and/or hippocampus. OCD, on the other hand, seems to be characterized by malfunction in a circuit comprising the orbitofrontal cortex, anterior cingulate cortex, striatum, and thalamus.
(Hoarding, incidentally, is thought to engage different areas of the brain — which is one of the reasons some scientists feel it shouldn’t be categorized as a form of OCD. In fact, research led by David Mataix-Cols suggests that washing, checking, and hoarding each involve ’distinct but partially overlapping neural systems’.)
In especially severe cases of OCD — cases that respond neither to psychotherapy nor medication — surgery may be performed. (OCD is the only anxiety disorder to be treated by means of neurosurgery.) The operation, termed a cingulotomy, aims to break the OCD neurocircuit at the anterior cingulate. The success rate is moderate: a study of 44 patients operated on at Massachusetts General Hospital since 1989 found that 32% improved significantly, with a further 14% experiencing partial benefit. Some of these patients had undergone more than one cingulotomy.
OCD seems to run in families, though not to any great degree. Having a first-degree relative with OCD elevates your own risk of developing the disorder from around 3% to 7%. Genetic heritability is thought to be modest. Twin studies of OCD are rare, but some have found no evidence of heritability. On the other hand, a twin study of OCD-like symptoms estimated heritability at 36%.
With genes making a relatively limited contribution to OCD, the spotlight falls onto environmental factors.
OCD has been linked to traumatic events in childhood (especially sexual abuse); relatively low socio-economic status; and hostile or neglectful parenting. However, these are also experiences that make a person vulnerable to anxiety disorders in general, and indeed to depression, alcohol and drug issues, and a wide range of psychiatric problems. The search for environmental influences specific to OCD continues.