Why People With OCD Fear Things They Shouldn't Fear

University of Minnesota's Christopher Hunt discusses his new research on obsessive-compulsive disorder and risk tolerance.

By Mark Travers, Ph.D. | September 4, 2021

A new article appearing in the academic journal Clinical Psychological Science offers insight into why people with obsessive compulsive disorder engage in what psychologists refer to as "catastrophizing," or the repeated mental simulation of highly unlikely catastrophic events. According to the authors, it has to do with a flawed perception of the likelihood of low probability events.

I recently spoke with Dr. Christopher Hunt, the lead author of the research, to discuss his findings in more detail. Here is a summary of our conversation.

What inspired you to investigate the topic of obsessive compulsive disorder (OCD) and risk tolerance and what did you find?

My inspiration for this topic stems from my clinical experiences conducting exposure with response prevention (ERP) therapy with OCD patients. When I first began seeing OCD patients, their fears seemed highly specific, if not totally unique to them; over time, however, I began to realize that the same, highly specific fears arose over and over again, even for patients of vastly different backgrounds. This made me wonder what commonality might underlie these seemingly disparate fears, and eventually, I realized that virtually all could be considered improbable catastrophes: events with an absurdly low probability of occurring but which would be truly terrible were they to occur (e.g., catching HIV from a doorknob, unknowingly committing a hit-and-run). As an experimental psychopathology researcher, I wanted to find out whether individuals with OCD symptoms would be sensitive to this category of threat — an improbable catastrophe — when they encountered it in the laboratory.

What are the theories around the causes of OCD and what percentage of the population does it affect?

Like most mental illnesses, genetics appear to play some role in the etiology of OCD, as genes account for between 27-47% of the variability in OCD for adult-onset cases and a higher percentage for child-onset cases. There are also certain neurobiological circuits that are perturbed in those with the illness, particularly the cortico-striatal-thalamic (CSTC) circuit. There are several different psychological theories regarding the origin of OCD, each with modest but not complete empirical support. Cognitive Appraisal Models (CAM) are perhaps the most well-known. These stipulate that intrusive thoughts are actually a normal part of human experience and that the tendency to catastrophically misinterpret the nature of the thought (rather than having the thought itself) is what leads to and characterizes OCD. For instance, while we all might have a fleeting, disturbing thought such as 'what if I jump out of the window of this 10-story building?', most of us would not give this thought much attention and would soon forget about it. In contrast, those with OCD might become greatly disturbed by this thought, perhaps questioning whether they are secretly suicidal and spending the remainder of the day distressed about this possibility. In support, researchers have found that almost everyone endorses experiencing an intrusive thought on at least an occasional basis, whereas only 2.5% of the population will meet clinical criteria for OCD in their lifetime.

How does your research inform clinicians' efforts to effectively treat OCD and obsessive-compulsive symptoms?

I think the major way this research can inform clinicians' efforts to effectively treat OCD is to help OCD patients make better sense of why they fear the things that they do. For instance, consider a patient who is concerned about contracting HIV from public surfaces, checks their stove repeatedly to prevent household fires, and also fears they will be severely punished by God for having a fleeting immoral thought (all common OCD fears). Learning that these seemingly random and bizarre fears are actually all manifestations of the same thing — a fear of improbable catastrophes — should hopefully afford the patient a greater understanding of their disorder and greater hope that it can be overcome. I think this knowledge could also help patients better cope with the emergence of new obsessive-compulsive fears, which often arise in the years following treatment. Instead of viewing these new fears as entirely new problems, they could instead see them as simply another example of their fear of improbable catastrophes, which they would have learned to effectively manage during a previous stint in therapy.

Aren't we all somewhat "irrationally" afraid of low probability but highly catastrophic events (like shark attacks and plane crashes)?

There are certainly some improbable catastrophes that we as a society tend to be more afraid of than we should be — shark attacks and plane crashes being great examples. However, we typically do not act on these fears like those with OCD do: most of us still fly on planes, most still swim in the ocean without issue. We know that these threats l are technically possible, but their minute chance of occurrence does not bother us to the extent that it affects our behavior or thinking in any significant way. In contrast, those with OCD are so bothered by the potential of an improbable catastrophe occurring that they will spend hours gaining reassurance that it will not happen, such as cleaning their hands repeatedly to eliminate any possibility, however small, of contracting a deadly infectious disease. Additionally, concerns about improbable catastrophes in society at large may be driven by factors like the availability heuristic, which is where we overestimate the probability of a negative event because we have recent examples that come to mind (think media coverage or plane crashes or shark week on National Geographic). Some improbable catastrophes feared by those with OCD have no such examples, as they are completely unprecedented or deemed impossible by medical science (e.g., contracting HIV from a doorknob).

Did you find any gender or demographic differences in how OCD tends to be expressed? Did people from different backgrounds develop different OCD symptoms?

Gender and demographic differences were not examined in the current paper but I did recently author a review on this issue. Using data from past studies and over 9000 OCD patients, I found there to be only very small differences in the extent to which patients of different genders, ages (child vs. adult), and cultures (Asia vs. U.S./Europe vs. South America vs. Middle East) exhibited different types of obsessions and compulsions. This again leads back to the notion that typical OCD fears all trigger some underlying sensitivity that most OCD patients possess. My research suggests this commonality may be a heightened sensitivity to improbable catastrophes.

What techniques might you advise people to explore if and when they experience threat overestimation/catastrophization?

Like most anxiety disorders, OCD appears to respond best to cognitive behavioral therapy, particularly exposure with response prevention. In my opinion, cognitive techniques are most useful for addressing distortions that pertain to the cost of feared consequences. For instance, some patients with OCD have what is known as an inflated sense of responsibility for negative consequences, which means that they may perceive catastrophic events as even worse than others because they are more likely to perceive the terrible event as being their fault. Cognitive techniques like gathering evidence for and against these beliefs can be helpful in reducing these distortions.

In contrast, I find exposure therapy (ERP) to be particularly effective in addressing inflated estimates of a catastrophic event's probability. This is because most OCD patients already know that the event they fear is extremely unlikely, so they typically do not need to address this belief with cognitive techniques. Rather, the patient continues to be bothered by the minute possibility that the feared consequence could occur. Repeatedly experiencing that the terrible event they fear does not occur via exposure helps bring their experience in line with their low estimation of the negative event's probability. Of course, abstaining from compulsions when facing one's fear is critical so that the patient knows the event truly does not occur and didn't just not occur because they prevented it with their compulsions.

Where would you like to see this research go in the future? Do you have any plans for follow-up studies?

I think the most important next step is to replicate this finding in a sample with more severe and diverse OCD symptoms. For instance, we will need to verify that OCD patients with primarily contamination symptoms, primarily checking symptoms, primarily sexual or religious OCD symptoms, and others, all exhibit similar sensitivity to improbable catastrophes. Later on, I hope to examine whether the sensitivity to improbable catastrophes can predict treatment outcomes or whether it reduces with successful therapy. This step will be key to evaluating whether sensitivity to improbable catastrophes can serve as a useful treatment target in the development of future OCD interventions.