Attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD) share some similar symptoms, which make it difficult for the untrained eye to tell them apart. Not only is it possible to be misdiagnosed, but in some cases, ADHD and OCD occur together, as dual diagnoses. That’s why, if you think you—or someone you know—could be struggling with one or both of these disorders, it’s important to really know the facts. 

We spoke with Dr. Patrick McGrath, psychologist and Chief Clinical Officer at NOCD, for a nuanced take on OCD and ADHD, how they are related, whether you can have both, what the treatments are, and more. 

ADHD vs. OCD

Attention deficit hyperactivity disorder (ADHD) is a mental health condition that affects around 1 in 10 children and 1 in 20 adults. According to the fifth edition of the diagnostic and statistical manual of mental disorders (DSM-V), ADHD is characterized by “a persistent pattern of inattention or hyperactivity-impulsivity that interferes with functioning or development.” For example, a child with ADHD may struggle to pay attention to details, follow instructions, or sit still. As a result, they’re unable to complete tasks at school or develop normal social relationships.  

Obsessive-compulsive disorder, a mental health disorder that affects millions of people in the U.S. each year, is defined by the presence of unwanted images, thoughts, beliefs, feelings, and urges that cause distress or anxiety (called obsessions). People with OCD often engage in repetitive physical behaviors or mental actions in an attempt to relieve the distress caused by their obsessions or avoid unwanted outcomes (called compulsions). 

What causes OCD and ADHD? Understanding the Underlying Biology

Evidence suggests that both OCD and ADHD are partly caused by dysfunction in the same brain regions and systems. Specifically, they are correlated with abnormal activity of the frontostriatal system, a part of the brain involved in executive functions such as short-term memory, planning, and behavioral control.

Interestingly, though both conditions are associated with dysfunction in the same regions, their characteristic abnormalities are opposite: while ADHD is correlated with decreased activity in this part of the brain, OCD is associated with overactivity. 

As these conditions relate to neurotransmitters (chemical messengers in the brain), both disorders are associated with imbalances in neurotransmitter levels. However, while OCD is correlated with low serotonin levels, ADHD is connected to dopamine dysfunction. This has important implications for which medications are best used to treat each condition.

How Can I Tell if I Have OCD or ADHD?

Here are four questions you can use to assess whether you’re experiencing OCD or ADHD.

#1: Do I Experience Intrusive Thoughts?

Though anyone can experience an unwanted thought from time to time, obsessions are not a distinguishing feature of ADHD. So, if you often experience intrusive thoughts, images, or urges, you’re more likely to have OCD.

#2: Do I Perform Compulsions?

Since individuals with ADHD don’t experience compulsions as people with OCD do, if you don’t find yourself performing mental or physical actions in order to rid yourself of anxiety and uncertainty or to prevent an unwanted outcome, that means you probably don’t have OCD.

#3: Am I Impulsive or a Risk-Taker?

By and large, individuals with OCD tend to be fairly cautious and opposed to taking risks. This contrasts with ADHD, which is often characterized by impulsivity and risk-taking behaviors. 

#4 Have Stimulants Caused More Intrusive Thoughts?

If a patient is having trouble with attention and executive control, they may be prescribed a category of medications called stimulants. While these help people with ADHD, they are generally bad for people with OCD and anxiety disorders. If you’ve been prescribed a stimulant and it made you obsess and ruminate more, that could be evidence that you have OCD.

Misdiagnoses: Why it’s easy to confuse the symptoms of OCD and ADHD 

Despite the differences, misdiagnoses can occur—and they can go both ways. Here are some reasons why OCD could be misdiagnosed as ADHD, and vice versa.

Why OCD Be Misdiagnosed as ADHD

Experts suggest that OCD can frequently be misdiagnosed as ADHD. The reason is that people with OCD often experience difficulties with attention and executive functioning—which are key traits of ADHD. For instance, people with OCD can become severely distracted by intrusive, upsetting thoughts, which can make it difficult to pay attention to anything else and interfere with their daily functioning.  “It can appear as if they’re not paying attention at work or in school when the reality is they’re doing all sorts of stuff involving obsessions and compulsions in their head,” shares Dr. McGrath. “And because of that, they might look like they have ADHD when that’s not actually the case.” 

Why ADHD Be Misdiagnosed as OCD

It’s also possible for ADHD to be misdiagnosed as OCD.

Generally speaking, ADHD does not involve obsessions or compulsions. However, as Dr. McGrath notes, it can appear that way. For example, though ADHD is associated with distractibility, researchers have found that people with the condition can become “hyperfocused” on particular tasks or topics. However, this type of “obsession” is entirely distinct from the kind associated with OCD. This is because individuals with ADHD generally do not experience intrusive or unwanted thoughts, images, and urges, though they can, especially if they also have OCD. 

Likewise, individuals with ADHD may engage in behaviors that appear to be similar to compulsions. For example, a child who is easily distracted may spend an excessive amount of time ordering, arranging, and cleaning things. But while these may appear similar to certain behaviors in people with OCD, they aren’t compulsions, as they aren’t done to alleviate anxiety associated with obsessions or to prevent a bad outcome. 

Can You Have Both OCD and ADHD?

Yes, it is possible to have both conditions. In fact, it’s pretty common—estimates suggest that up to 30 percent of children and adolescents with OCD also have ADHD.

However, some argue that a genuine combined diagnosis is actually much less common. This is because, as noted above, individuals with OCD rarely exhibit impulsivity or risk-taking behavior. Also, because ADHD and OCD are associated with opposite activity in certain parts of the brain, some feel that it’s unlikely for a person to have both. 

In either case, many individuals show sufficient symptoms of both conditions to be diagnosed with both OCD and ADHD.

Does ADHD Make OCD Worse?

ADHD can exacerbate the symptoms of OCD. For example, one study found that compared to adults with OCD alone, those additionally diagnosed with ADHD engaged in more obsessions and compulsions. The authors hypothesize that the additional impairments in executive control caused by ADHD may make it harder for individuals with both disorders to resist compulsions that make OCD worse. 

In addition to increasing the frequency of obsessions and compulsions overall, the combination of disorders may make some intrusive thoughts and OCD subtypes more common. In the study referenced above, the researchers found that obsessions and compulsions related to hoarding, symmetry, and fears about disorder were more common among those with both conditions. 

Can OCD and ADHD Be Treated at the Same Time?

OCD and ADHD  can both be effectively treated at the same time through therapy, medication management, or both. It’s absolutely crucial to work with a therapist who has specialty training in OCD, so treatment approaches are appropriate for both conditions.

Therapy

Exposure and response prevention (ERP) is the most popular and effective treatment for OCD. For this treatment, individuals with OCD are exposed to some stimulus that triggers an obsession (e.g., a fear of health contamination) without engaging in compulsions in response (e.g., seeking reassurance through internet searches or doctors). Over time, preventing compulsions in response to obsessions and anxiety allows people with OCD to tolerate uncertainty and distress, while reducing the strength of the compulsive urges. 

ERP is considered the gold standard for OCD treatment and has been studied extensively in decades of clinical research demonstrating its effectiveness.

ADHD can also be managed with ERP, but it’s often combined with other behavioral therapies. For example, therapists may additionally employ parenting training,  goal-setting strategies, and lifestyle skills training. In general, it benefits from a more holistic approach that draws from several therapeutic techniques.

Medication

ADHD is often treated with a class of medications known as stimulants, such as methylphenidate or dextroamphetamine-amphetamine, which increase the amount of dopamine, a chemical messenger involved in motivation and reward learning. However, as Dr. McGrath highlights, they shouldn’t be used to treat people with both conditions: “You don’t give people with OCD a stimulant medication.” This is because it can intensify their anxiety and magnify their symptoms. 

Fortunately, there are also several non-stimulant medications for ADHD. Some examples include

• Atomoxetine
• Clonidine
• Guanfacine
• Viloxazine

These medications work on different chemical responses in the brain to avoid the possible anxiety-inducing effects of traditional stimulants. 

OCD is typically treated with selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine (Prozac) or sertraline (Zoloft), paroxetine (Paxil), citalopram (Celexa), and escitalopram (Lexapro), which impact serotonin, a chemical messenger believed to play a role in the symptoms of OCD, anxiety disorders, and depression. These medications may be combined with the non-stimulant alternatives listed above to treat patients with both OCD and ADHD. 

Where to go for OCD treatment

If you’re at all overwhelmed about what a treatment path will look like for you, rest assured that there are experts who can help so you don’t have to figure out anything alone. At NOCD, for example, all of our therapists specialize in OCD. Many of them have dealt with OCD themselves and understand how crucial ERP therapy is.