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OCD and ADHD: The Relationship Between Them

OCD and ADHD: if you aren’t diagnosed with one (or both) of these disorders, you probably aren’t too familiar with the exact differences between the two.

Both OCD and ADHD are mental health disorders that are often greatly misunderstood by the general public. People who are diagnosed with these conditions are usually labeled as “quirky” or even “weird”, and there is little to no understanding about how truly detrimental and painful both of these disorders can be.

OCD and ADHD, although they share many characteristics, are not the same disorder. They do, however, have many important similarities, which can lead to people getting misdiagnosed. Even though some people suffer from both disorders at the same time, it’s important to differentiate between the two – because treatment for OCD looks vastly different from treatment for ADHD.

This guide will explain everything you need to know about the similarities and differences between OCD and ADHD, and why it’s crucially important to tell them apart.


What Are The Symptoms of OCD and ADHD?

First, let’s talk about what defines OCD and ADHD as disorders. Although they’re both diagnosable mental health conditions, the symptoms that define them are very different.

What is OCD?

If you’ve been following this blog, you’re probably very familiar by now with the symptoms of OCD.

OCD, or Obsessive-Compulsive Disorder, is a mental illness that’s often called “the doubting disease”, because, at its core, it’s an inability to tolerate any level of doubt. The disorder is defined by the presence of two specific symptoms: obsessions and compulsions.

Obsessions are intrusive and unwanted thoughts that pop into someone’s head. We all have random thoughts like this sometimes, but what makes an obsession different is that the person with OCD ruminates on the thought. The thought causes them a great deal of distress, anxiety, and fear, and they feel like they’d be willing to do anything just to get the thought to leave their brains. They’re unable to think about anything else when an obsession gets lodged in their minds.

Compulsions are what, for people with OCD, follows an obsession. These are any kind of repetitive, ritualistic behaviors (whether it’s mental or physical) that are meant to reduce the anxiety that’s caused by an obsession. This could be anything from washing one’s hands over and over again or checking locks (the compulsions that are most commonly associated with OCD) to asking for reassurance or mentally reviewing memories.

To meet the diagnostic criteria for OCD, these obsessions and compulsions must cause a significant decrease in functioning for the person in important areas of their life, like employment or relationships.

OCD can be a debilitating disease when left untreated, and is listed by the World Health Organization as one of the top ten causes of disability in the world.

What is ADHD?

ADHD, or Attention Deficit and Hyperactivity Disorder, is one of the most common neurological disorders in the world, affecting over 8% of children and over 2% of adults. As its name suggests, people with ADHD have difficulties maintaining focus, as well as with hyperactivity or impulsivity.

Some of the symptoms of ADHD might be constant daydreaming, an inability to sit still, impulsive or risky behaviors, forgetting or losing important things, talking too quickly or too much, and making constant careless mistakes.

It’s important to note that in the DSM-V, ADHD is split up into three subtypes: the primarily inattentive type, the primarily impulsive or hyperactive type, and the combined type (which means the person is both hyperactive and inattentive).

Again, like all mental health disorders, the symptoms must cause significant distress or impairment to the person to meet the diagnostic criteria. People with ADHD often experience lifelong struggles with school and work, and can also have trouble making and sustaining relationships because of their symptoms.

Did you know, our our self-help course has helped thousands of OCD sufferers better manage their symptoms?

"My OCD is finally manageable"

Jennifer S

OCD and ADHD: Similarities and Differences

On the surface, it may seem like OCD and ADHD are completely different conditions that could never be confused for each other. While this is true (OCD and ADHD are different conditions), these two disorders can often present in similar ways – which leads to some confusion. However, when we look at them deeply, we start to understand just how different they are.

Similarities Between OCD and ADHD Symptoms

On paper, it might seem like OCD and ADHD have nothing in common at all. In presentation, though, these disorders are often misdiagnosed for each other. More specifically, children who actually have OCD are often misdiagnosed with – and treated for – ADHD.

Fidgeting or Compulsions?

We think that part of the reason why these two conditions are confused is because people with OCD often engage in repetitive behaviors that look strange to people watching them. To an outsider, it might just look like the person can’t sit still or that they’re constantly fidgeting. For example, consider the example of a young boy who, instead of completing his homework every day, is constantly re-arranging his school supplies.

It’s important for treatment providers to get to the root of why that person is engaging in these behaviors. Are they truly just fidgeting because they feel like they can’t sit still, or is there an underlying obsession that’s causing these behaviors?

For example, is the little boy playing with his school supplies because he’s distracted and hyperactive, or is he re-arranging them because he has an overwhelming feeling that something is “off” or that something terrible will happen until his desk is arranged “just so”?

If it’s the former, that boy may qualify for ADHD. If there is an obsession underlying the behavior, however, the re-arranging might be a compulsion, which would make it more likely to be OCD.

What About ADHD Intrusive Thoughts?

If you have been diagnosed with ADHD, you might have thought to yourself, as you were reading about OCD obsessions: “But I get intrusive thoughts too!”

And you’d be right; people with ADHD do report that they experience intrusive thoughts that cause more distress to them than they do to people who are neurotypical. People with ADHD have intrusive thoughts that just won’t go away, and may find that they ruminate on them.

There’s not a clear answer on whether an intrusive thought is caused by ADHD or OCD. One defining factor of an OCD obsession, though, is that they usually revolve around a specific theme, which we’ll talk more about later.

If you’re unsure about the cause of your intrusive thoughts, the only person who can give you the answer you’re seeking is a licensed mental health professional. By studying not only your intrusive thoughts, but the other symptoms you’re experiencing as well, a professional should be able to distinguish between the two disorders.

Inattention in ADHD and OCD

As we talked about before, one of the defining features of ADHD is inattention; people with this disorder have trouble regulating their focus, often swinging between not being able to maintain their attention or becoming hyperfocused on something that captures their attention.

Although inattention isn’t a defining feature of OCD like it is for ADHD, people with OCD can definitely also struggle with this. This can be seen as a shared characteristic between the two disorders, but there are big differences between what causes inattention in ADHD and in OCD.

For people with ADHD, inattention is caused by a biological function in the brain. Although people with OCD do sometimes struggle with paying attention, it isn’t likely to be caused by biology in their case – at least not in the way that it is with ADHD.

A more likely explanation is that, if someone with OCD does have trouble with focus, it’s caused by anxiety. Obsessions, remember, bring with them an intense amount of anxiety, fear, and dread. Anxiety makes it hard for anybody to have great focus, not only people with OCD.

Neurobiological Similarities Between ADHD and OCD

Both OCD and ADHD are neurological disorders, which means that both of these illnesses biologically affect people’s brains.

One important similarity in the way that these disorders affect the brain is that they both seem to affect the frontostriatal pathway. This is the part of the brain that is responsible for important executive functions like self-control, task-switching, decision-making, and planning.

However, that’s the only thing that these two disorders have in common neurobiologically. The ways in which the disorders affect the frontostriatal pathway are completely different, which we’ll learn more about later.

How OCD and ADHD Are Different

Despite the few similarities in how these two disorders present, OCD and ADHD are actually quite different.

Specific “Themes” of OCD Obsessions

We’ve already talked about the presence of intrusive thoughts in people with ADHD (as well as OCD). Although all types of intrusive thoughts cause anxiety, there is an essential defining factor to OCD thoughts that isn’t present in any other disorder: obsessions revolve around a very specific theme.

People with ADHD who get intrusive thoughts are likely to experience them about a range of topics; they may be triggered by whatever is in front of them at the moment. People with OCD, however, experience intrusive thoughts that revolve around a specific topic that causes them a great deal of distress.

As an example, we can take one of the most common OCD obsessions, which is the fear of contamination. Someone with contamination OCD will experience intrusive thoughts about the specific fear of becoming contaminated or dirty. The intrusive thought might even be more specific than that; for example, maybe they get intrusive thoughts about being contaminated any time they’re around toilets, but don’t experience anxiety about anything other object.

Other themes of OCD range from pedophile OCD (in which the person is obsessed with the idea that they may be a pedophile without knowing it) to suicide OCD (in which the person is obsessed with the fear that they may “accidentally” commit suicide), and an infinite number more.

In contrast, people with ADHD are unlikely to experience thoughts that revolve around such a specific theme.

Impulsivity in OCD and ADHD

Impulsivity and compulsivity have sometimes been studied on a spectrum, and these researchers had a point; when you think about it, both impulsive behavior and compulsions are behaviors that people perform even though they might not really want to, and usually despite negative consequences.

However, when we think of impulsive behavior as risky behavior, we can start to clearly see the difference between OCD and ADHD. People with OCD are much less likely than people with ADHD (and even less likely than the greater population) to engage in risky impulsive behaviors. Think about it: people with OCD are concerned with avoiding any amount of risk, not inviting it. On the other hand, people with ADHD impulsivity aren’t able to think so carefully about the risk associated with their behaviors.

Neurobiological Differences Between ADHD and OCD

In terms of the brain science, one of the only things that ADHD and OCD have in common is that they both affect the frontostriatal system. How the disorders affect this part of the brain, though, is vastly different between the two disorders. In fact, OCD and ADHD affect the brain in literally opposite ways.

People with OCD have been found to have an overactive frontostriatal system, while people with ADHD have an underactive one. In other words, people with OCD think too much about decisions and plans, for example, while ADHD people think too little about them.

This is the marked difference between compulsions and impulsivity, like we talked about before. Both groups of people have difficulties with executive functioning, but in opposite ways.

The Relationship Between OCD and ADHD

Now that we’ve differentiated between these two disorders clearly, let’s talk about how they’re related. Yes, OCD and ADHD are two separate disorders – but that doesn’t mean that they have absolutely nothing to do with each other.

OCD and ADHD are often confused and misdiagnosed for one another, because of the similarities that we discussed earlier. On top of that, a small population of people actually suffer from both of these disorders at the same time.

OCD and ADHD Can Be Co-Occurring Disorders

An important thing to remember is that mental health diagnoses aren’t meant to be boxes that you can never escape from. Yes, it’s important to receive the right diagnosis (so you can receive the right treatment), but many people don’t fit neatly into one diagnosis “box”.

In the same vein, many people fall into more than one “box”; they fit the diagnostic criteria for more than one mental health disorder.

OCD, especially, has a high co-morbidity rate with other mental illnesses; it’s estimated that up to 60% of people with OCD also suffer from at least one Major Depressive Episode in their lifetimes. It’s not hard to see why, considering the intense amount of suffering that OCD brings.

OCD and ADHD can also be co-occurring (this is just a fancy way of saying that someone can be diagnosed with both disorders at the same time). Estimates show that around 11% of people with OCD also have ADHD (although, to be fair, we have to note that other literature reviews have found a huge discrepancy in those numbers across studies, and claim that the comorbidity rates actually range between 0 and 60%). This number is even higher for children with OCD, with around 25% of them being dually diagnosed with ADHD.

Misdiagnosis of OCD and ADHD

Even though we can see that OCD and ADHD have different symptoms, there’s also a surprisingly high rate of misdiagnosis between the two.

Most often, this happens with children; like the example of the young boy before, it can be hard, even for professionals, to figure out the root cause of children’s behavior. Especially when children aren’t verbal or can’t express everything that’s going on inside of them, it can be tricky to figure out what the exact causes are. It doesn’t help that children’s behavior is often reported on by parents and teachers, not the children themselves.

This might lead to someone with OCD getting misdiagnosed with ADHD, and vice-versa, because of the sometimes-similar presentations of these two disorders.

Although there are no specific statistics available for exactly how many people are misdiagnosed, the research shows that the misunderstanding of OCD, especially, often leads to inaccurate ADHD diagnoses. Some research that points towards this is the fact that around 25 percent of children with OCD are also diagnosed with ADHD, but that number goes down by about half for adults with OCD.

How do we explain this discrepancy? Are adults with OCD just “growing out of” ADHD? Maybe, but probably not. What many researchers hypothesize is that this number is so drastically different because children’s OCD behavior is often misdiagnosed as ADHD. Often, as they get the OCD treatment that they need, symptoms that might look like ADHD on the surface disappear.

The Difference in Treatment of OCD and ADHD

Here’s where we get to why it’s so important to receive the correct diagnosis: the recommended treatments for ADHD and OCD are vastly different, and without the right treatment, it’s impossible to recover from either disorder.

ADHD Treatment and Medications

ADHD is usually treated with a combination of behavioral therapy and medication. Behavior therapy teaches people, especially children, techniques to manage the dysfunction that ADHD causes, and the medications actually work to improve these functions by directly affecting the brain.

You might think, well, that seems harmless. It wouldn’t hurt to try these medications if you think you might have ADHD, even if you aren’t sure. Although, of course, being prescribed the wrong medication isn’t likely to have fatal consequences, it’s far from harmless to take ADHD medication if you really have OCD.

ADHD medications like Ritalin have been shown to actually exacerbate OCD symptoms. Remember that neurobiologically, people with OCD have an overactive frontostriatal pathway while people with ADHD have an underactive one. It’s not hard to see why a medication that’s designed to activate this part of the brain even further would be harmful to someone with OCD.

That’s why doctors recommend that if medical professionals are really unsure about whether or not a patient has ADHD or OCD, to start by trying to treat OCD. OCD treatment for someone with ADHD probably isn’t going to help much, but it’s much less likely to cause harm or worsen symptoms.

OCD Treatment: Exposure and Response Prevention

The recommended treatment for OCD is also very specific: a CBT-based intervention called Exposure and Response Prevention (or ERP). Although ERP is based on CBT principles, it’s far from general CBT treatment.

Specifically designed to help people with OCD get out of the obsession-compulsion cycle, ERP helps patients to tolerate more and more of the anxiety that obsessions bring without resorting to performing compulsions.

Again, ERP isn’t likely to make ADHD worse, but it’s also unlikely to help. People with ADHD aren’t fidgeting or engaging in behaviors specifically to decrease their anxiety; most of the time, if they are hyperactive, they’re just moving unconsciously because they can’t help it. Since there are no compulsions there to begin with, there are no compulsions to “prevent” – rendering ERP useless for this condition.

The psychiatric medication that’s most often used in the treatment of OCD symptoms is a class of antidepressant drugs called SSRIs. Since many people (up to 30 percent) with ADHD also experience depression, this OCD treatment isn’t likely to be harmful for people with ADHD, either – and might even be helpful in some situations.

Looking for OCD Treatment?

First of all, it’s important to receive a correct diagnosis. Your first step on your mental health journey should be to speak with a qualified mental health provider to figure out whether you are suffering from OCD, ADHD, or another disorder.

If you do have OCD, then there is effective treatment out there for you. You don’t have to live with these symptoms forever, and many people have recovered from this debilitating illness. Impulse Therapy is a self-guided program that uses evidence-based practices like ERP to help people recover from OCD. We are here for you, every step of the way.

Our self-help OCD therapy course has helped 1000s of OCD sufferers since 2018.

"My OCD is finally manageable"

Jennifer S


Natalie Saya Des Marais

Saya Des Marais, MSW is a health and wellness writer and Masters-level mental health professional with over 10 years of experience in the field. Some of the topics she's written about include but are not limited to: mental illness, addiction and recovery, parenting, depression, anxiety, mental health treatment, self-esteem, mindfulness meditation, and yoga.

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