If you have OCD or know someone with the condition, you may wonder just how common it is. After all, nearly everyone has heard of OCD, but few people truly understand what it is. While it might seem simple to answer, finding an accurate estimate of the number of people with OCD has proven difficult, leading some to underestimate OCD’s prevalence.
We spoke with Dr. Jamie Feusner, Chief Medical Officer at NOCD, to gain a clearer picture of how common OCD is and what’s involved in figuring that out. Here’s what we learned.
What is the current best estimate?
Obsessive-compulsive disorder is a mental health condition characterized by two primary symptoms: obsessions and compulsions. Obsessions are intrusive and distressing thoughts, images, and urges. Compulsions are mental or physical actions done in response to obsessions to alleviate distress or prevent bad outcomes from occurring.
Research suggests that over the course of their lives, an estimated 2.3% of the population, or 1 in 40 people, will develop OCD, and that 1.2% of people have OCD in any 12-month period.
However, the true prevalence of OCD is likely higher, as social stigma and imperfect assessment tools cause OCD to be under-reported.
How are these estimates calculated?
To estimate the prevalence of OCD, researchers complete the following two tasks.
Step 1: Gather a random sample
First, researchers need to gather a relatively random sample of the population, meaning that any member of a population has a roughly equal chance of being in it. This helps to ensure that the research sample is representative of the population it intends to study, whether that’s a demographic group, a particular country, or the entire world.
Step 2: Choose and administer a diagnostic tool
With a random sample in hand, researchers must have a test they can use to assess whether each person in it does or does not have OCD. Dr. Feusner notes that studies on the prevalence of OCD “asked people questions to determine if they meet Diagnostic and Statistical Manual of Mental Disorders (DSM) or International Classification of Disease criteria for OCD.”
From there, researchers look at the data, learn what percentage of the group met the diagnostic criteria for OCD, and—because the sample was randomly chosen—can infer that a similar percentage of the population participants were chosen from will have OCD.
What are some challenges to calculating these estimates?
Though our current estimates provide us with a pretty good idea of how common OCD is, there are still challenges and obstacles that get in the way of generating an even more reliable number. Here are two significant difficulties.
#1: Mental health stigma keeps people from sharing their symptoms
Though the public perception of mental health is improving, negative stereotypes are still common. Importantly, these views and beliefs are often also held by those with mental health conditions—this is known as “self-stigma” or “internalized stigma.” For example, a recent review of self-stigma found it remains common across the globe for serious mental health conditions such as OCD and bipolar disorder.
Self-stigma can cause people with mental health conditions to conceal their symptoms and experiences. Since studies on the prevalence of any mental health condition ultimately depend on people being open and honest about their mental health, self-stigma poses a challenge to obtaining an accurate result. In particular, if self-stigma is causing patients with mental health conditions not to discuss their symptoms, studies on the prevalence of those conditions will end up underestimating how common they are.
Given that OCD often centers around taboo or stigmatized topics, and people with OCD are sometimes falsely portrayed as violent or dangerous, self-stigma most likely impacts studies on the OCD population. For example, one study found that 75% of people with OCD said they “felt ashamed of [their] problems.”
#2 Assessment tools aren’t always reliable
As was noted above, once you have a random sample of people and want to assess how many have a mental health condition, you need a tool that will reliably tell you who does and does not have it.
When doctors look for many non-psychiatric conditions, like heart disease or cancer, they don’t just base their determination on a verbal description of symptoms, though this may prompt further testing. Instead, they can also rely on “biological markers” of these conditions. However, as Dr. Feusner notes, “for all psychiatric disorders, there is no objective ‘biomarker’ with high sensitivity and specificity.” In other words, studies that involve establishing a diagnosis rely on verbal responses when asked structured interview questions. The researchers assess responses from participants to decide whether they have a particular condition—in psychiatry, typically based on the DSM or the International Classification of Diseases (ICD). For these structured interviews to serve as reliable detection devices, they must be clear, accurate, comprehensive, and widely understandable.
The DSM is the handbook used by healthcare professionals in the U.S. and much of the world as the authoritative guide for diagnosing mental health conditions. Despite its widespread use, it has its limitations, as do other tools like the International Classification of Diseases (ICD). “The DSM criteria are not perfect in their ability to detect OCD and might result in misdiagnosis,” says Dr. Feusner. One reason why is that their descriptions are incomplete. “For OCD, because there are so many subtypes, each with many varieties, it is not always clear to people receiving diagnostic interviews if what they experience constitutes an obsession or compulsion—it depends on their understanding and interpretation of the questions they’re asked. This seems to be particularly true for intrusive obsessive thoughts having to do with violence, sex, religion, sexual orientation, or relationships.”
Because guidelines like the DSM are imperfect tools, certain people with OCD may go undetected in studies of its prevalence.
What about “mild” or subclinical OCD?
OCD is not an all-or-nothing condition. The symptoms that characterize it exist on a spectrum, meaning it’s possible to experience them to various degrees. For example, some people might spend more time obsessing or engaging in compulsions than others.
Notably, according to the DSM, engaging in some obsessions or compulsions alone does not mean that a person meets the criteria for an OCD diagnosis. For example, obsessions or compulsions must be time-consuming or cause clinically significant distress and/or impairment in social, occupational, or other important areas of functioning. This means one can actually both experience obsessions and engage in compulsions and not be diagnosed with OCD. Researchers often refer to this as “subclinical OCD.”
A few things are worth mentioning here. First, the fact that one can have “subclinical OCD” is relevant for how we think about how prevalent OCD is. While around 2% of people meet the diagnostic criteria for OCD in their lifetime, this figure may be much higher for subclinical cases. For example, the same study found that more than a quarter of respondents reported obsessions or compulsions at some time in their lives.
This matters because these individuals may still be affected by some OCD symptoms, even when they’re not severe enough to warrant a diagnosis. These experiences could still interfere to a certain degree with their ability to function.
Moreover, OCD can start out at subclinical levels. With some exceptions, people typically don’t go from experiencing no symptoms one day to meeting diagnostic criteria the next. Experts have argued that when symptoms are caught early, treatment like exposure and response-prevention (ERP) therapy theoretically may work as a preventive measure. As a result, it’s important for both clinicians and the general public to be aware of subclinical OCD and how to identify it.
Is OCD becoming more common?
According to some studies, the number of OCD diagnoses has increased over time. For example, one study found that reported OCD diagnoses have increased in Denmark, Finland, and Sweden compared to the 90s.
But does this mean OCD is actually becoming more common over time? “I do not believe the field knows the answer to this question,” says Dr. Feusner. He points to several factors that may explain why reported diagnoses are increasing even though the number of people with OCD isn’t. Specifically, he suggests that the public has become more aware of OCD, and mental health professionals are better trained at identifying OCD and its subtypes. “The field of mental health and health care in general perhaps have gotten gradually, but only slightly, better at diagnosing OCD, aided by more awareness in the general population of the many different types of OCD symptoms,” he says. “However, the lack of awareness and understanding still remains a significant problem.”
Of course, environmental stressors can impact rates of OCD symptoms and diagnosis. For example, a recent review concluded that both people with and without OCD before the pandemic showed increased symptoms of OCD throughout it, especially those who engage in compulsive handwashing and cleaning. In this sense, OCD, or at least the prevalence of obsessions and compulsions, can become more common for a period of time due to the presence of environmental factors that trigger new OCD symptoms or intensify existing ones.