Causes of OCD: the cognitive behavioural model explained

What causes OCD?

When people ask why OCD develops, a single explanation is rarely sufficient. OCD is a multifactorial condition. This means that biological, environmental and psychological factors often interact.

It is therefore useful to distinguish between vulnerability, triggering factors and the processes that maintain symptoms. A person may have increased vulnerability without developing OCD, and OCD can become stronger when doubt, distress and attempts to obtain certainty begin to form a fixed pattern.

Inherited and biological factors can increase a person’s vulnerability, but they rarely explain the whole picture on their own. Stress, loss, conflict or other life events may help trigger or intensify OCD in some people. Psychological factors concern how thoughts, doubt, responsibility and distress are interpreted, and which strategies the person uses to obtain relief.

The cognitive behavioural model is useful here because it shows how OCD can be kept going in everyday life. It does not explain the full cause of OCD, but it can make it clearer how psychological mechanisms can develop and maintain OCD.

OCD is characterised by obsessions and compulsions. Obsessions are unwanted thoughts, ideas, images or impulses that may feel threatening, aggressive, repulsive or senseless to the person experiencing them. Common themes include contamination, responsibility for harm, harm-related, sexual or religious intrusive thoughts, and a need for order or precision. Most people with OCD have several themes, and both the form and the content can change over time (Castonguay & Oltmanns, 2013).

The fact that a thought feels violent or wrong does not mean that the person wants it or will act on it.

Many people occasionally have intrusive thoughts that feel strange, unwanted or unpleasant. In OCD, the problem is often that the thoughts are given special meaning and start to feel as if they require an answer, certainty, neutralising action or reassurance.

In treatment, it therefore becomes important to look not only at which thoughts appear, but also at how the thoughts are interpreted and how the person responds to them.

Psychological causes and mechanisms behind OCD

In clinical practice, the cognitive behavioural model is often used to understand how OCD patterns can develop and be maintained (Salkovskis, 1985). The model should not be understood as a complete explanation of why OCD has developed in a specific person, but as a clinically useful way to examine how OCD can develop and remain active.

The model can be understood as a self-reinforcing sequence: vulnerability and triggering events can activate certain rules for living, which influence the interpretation of thoughts and situations. When the interpretation feels threatening, distress can arise together with a strong need to do something to obtain relief. That response can become compulsions or other safety behaviour.

The model reminds us that distress is not only about the thought or situation itself. It is also about the meaning the person gives to it. Fear in OCD can become stronger when intrusive thoughts, feelings or impressions are interpreted as overly significant or threatening.

Three things are especially important in the model: vulnerability, triggering events and rules for living. Vulnerability covers factors that can make a person more likely to develop OCD. Triggering events are stressful life circumstances or significant events that can activate the vulnerability. Rules for living are basic assumptions about oneself, other people or the world.

Rules for living are not usually deliberate choices. They are often learned ways of creating a sense of control, responsibility or safety.

Examples of rules for living may be:

• “If I am not completely sure, it is not good enough.”
• “If I have a thought about harm, it may mean that I am responsible.”
• “If something feels wrong, I have to do something until it feels right.”
• “I should be able to control my thoughts.”

In OCD, such rules for living may show up as particular forms of threat appraisal or misinterpretation. The person may overestimate responsibility, risk or the importance of thoughts, struggle with uncertainty, or feel that something has to be completely right before they can move on.

Predisposing factors may include:

• inherited genetic factors
• developmental vulnerabilities
• vulnerability linked to earlier stress or adversity
• a particularly sensitive threat system

It is possible to live with such rules for living without developing OCD. If the person later faces a period of stress or a major life change, for example a bereavement, divorce or loss, the rules may be activated. In some people, this can lead to obsessions and the development of OCD.

Rules for living can also be difficult to notice. They may influence the person’s reactions before the person has time to become aware of them.

When a situation or thought is interpreted through strict or threatening rules for living, it can start to feel threatening. It begins to feel highly significant and demands attention. The negative interpretation may create physical discomfort, anxiety, doubt or guilt.

For the person, it may therefore feel necessary to act on the distress. The response may become compulsions or other safety behaviour. This is a central part of the OCD pattern.

Compulsions are not always visible. They may also be hidden mental actions, for example mental checking and reviewing, internal reassurance, analysis, prayer, counting, trying to make the thought feel right, or repeated reassurance seeking.

When the compulsion is carried out, distress often decreases temporarily. This can make the compulsion or safety behaviour feel helpful.

In the longer term, however, the pattern may be strengthened because the person has fewer opportunities to learn that distress can subside without the ritual. A maintaining spiral may develop, where distress is gradually triggered in more situations and the OCD pattern spreads to more areas of the person’s life (Salkovskis, 1985).

For some people, the pattern can eventually affect everyday life so much that professional help is needed.

Why does OCD persist?

The cognitive behavioural model is not only a tool for understanding how OCD can develop. It can also explain why OCD may persist. Rules for living may be shaped by earlier experiences and become part of the person’s way of evaluating situations. Later, they can influence the interpretation of new situations, even without the person being fully aware of it.

Once the pattern becomes self-reinforcing, thoughts, bodily sensations and situations can quickly start to feel dangerous. The person may then end up doing the same thing again: checking, avoiding, neutralising or seeking certainty.

Because OCD is multifactorial, the pathway into OCD can look different from person to person. There may be different predisposing and triggering factors, even when the symptoms look similar. Two people can have the same OCD theme but very different life histories, vulnerabilities and triggering events. The model can therefore be used as a tool for examining the individual’s pattern, not as a simple explanation of why OCD has developed.

The model makes it clearer where treatment can intervene: not by debating every single thought, but by changing the pattern that follows the thought.

What does the model mean for treatment?

Treatment therefore does not focus only on the content of the thoughts, but on the pattern around them: the interpretation, the distress and the response that follows. In cognitive behavioural therapy, the person works both on understanding OCD-related interpretations and on gradually practising not carrying out rituals, avoidance or neutralising. A related model, the cognitive diamond, can be used to examine the interaction between thoughts, feelings, body and action in a specific situation.

Treatment is therefore not about convincing the person once and for all that the thoughts are harmless. It is about changing the response to thoughts, doubt and distress.

This is where exposure and response prevention becomes central. The person practises facing the situations, thoughts or sensations that trigger OCD distress without carrying out the usual compulsion or safety strategy. The goal is not to become completely certain or entirely free from distress straight away. The goal is to gain new experiences that thoughts, doubt and physical discomfort can be present without OCD deciding what the person does.