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Attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD) share some overlapping symptoms, and they can have similar effects on the way people function at school and on the job.

Although it isn’t common, it may be possible for people to have ADHD and OCD at the same time. It’s also possible to be misdiagnosed — one condition mistaken for the other.

Here’s a look at what ADHD and OCD have in common, along with how you can tell the two apart.

These two conditions share a lot of territory. Similar symptoms and similar effects can increase the possibility of a misdiagnosis.

ADHD is a developmental condition that causes people to be inattentive, impulsive, or overly active — sometimes all three.

People with ADHD often have a hard time completing projects and staying organized. The disorder can cause problems at school, at work, and at home.

Around 6.1 million children in the United States have been diagnosed with ADHD. That’s roughly 9.4 percent of the childhood population, making ADHD one of the most commonly diagnosed developmental disorders in the United States.

Symptoms of ADHD typically start before age 12 years, even if the diagnosis occurs later. They vary from person to person, especially in their severity.

Some people have more difficulty with attentiveness, while others may be more hyperactive. Most people experience some combination of these symptoms:

  • difficulty focusing or staying on task
  • problems keeping track of materials
  • trouble following through on complex projects
  • distractibility and forgetfulness
  • appearing not to listen when spoken to
  • increased need to be up and moving
  • fidgetiness
  • impulsivity
  • tendency to interrupt other people
  • excessive talking

OCD is a condition that causes people to have unwanted, intrusive thoughts (obsessions) along with behaviors they believe they must repeat (compulsions).

People with OCD often use their compulsions to try and quiet or counteract their obsessive thoughts. If left untreated, OCD can lead to anxiety, depression, and other health problems.

It’s important to note that though most people have both obsessions and compulsions, the diagnostic criteria states “obsessions, compulsions, or both,” so a person could have obsessions alone.

Although it’s less common than ADHD, OCD affects millions of people in the United States every year. Around 2.3 percent of the population has experienced OCD for some period during their lifetime.

OCD has two primary symptoms: obsessions and compulsions.

Obsessions are repetitive, upsetting, and unwanted thoughts. They may include:

  • intense fear of acquiring infections or experiencing contamination
  • thoughts of self-harm or harming someone else
  • unwelcome sexual or religious thoughts
  • strong need to make things orderly, symmetrical, or predictable

To relieve the anxiety these thoughts create, some people feel compelled to perform very specific behaviors. Compulsions may look like these behaviors:

  • extreme or excessive cleaning
  • counting rituals
  • precise organizing or arranging of objects
  • frequent checking and re-checking

What OCD causes people to fear, and how they respond to those fears, is highly individualized. But obsessions and compulsions take up a lot of time, creating conflicts in many areas of life.

These two disorders share certain symptoms and cause similar problems. And both disorders have a genetic connection.

Here are some of the other similarities between them.

Both conditions involve the same brain areas

Brain scans show that ADHD and OCD both produce atypical activity in the same neural pathway in the brain — the frontostriatal area.

This circuit is involved with a number of important cognitive and behavioral abilities such as:

  • attention-shifting
  • flexibility
  • habits
  • goal-directed behaviors

When the frontostriatal circuit isn’t working as it should, it can be harder for you to:

  • make decisions
  • remember things
  • plan
  • switch from one task to another

Both can interfere with academic and career success

ADHD is well known for the disruption it causes at school and work.

People with ADHD often have a hard time:

  • managing time
  • keeping up with supplies
  • remaining focused
  • completing complex tasks

They may be late to class or to work, and inattention can cause them to make frequent mistakes.

Similarly, the time involved in carrying out rituals, checking behaviors, and other compulsions can make people late to school or work.

Obsessions, compulsions, and the anxiety they cause can affect the ability to focus and follow through on tasks. Both conditions can affect grades, attendance, and performance.

Both disorders can affect your ability to pay attention

One of the chief characteristics of ADHD is the inability to pay attention for longer periods of time. If someone calls your name, you might not hear it because you’re distracted by something else.

OCD can also make you seem inattentive but for a different reason. You might be so preoccupied by an obsession or a compulsion that you’re not focused on what’s happening around you.

Both impact relationships with family, friends, and others

ADHD and OCD both require extra support from the people in your life. Family members may be involved in helping you seek treatment or carry out a treatment plan.

They may be instrumental in helping you learn coping skills. Ideally, they will go the extra mile to make sure you feel loved and supported — and they may sometimes feel stressed, frustrated, or worried about you, too.

Both can trigger anger, anxiety, and depression

Stress can make the symptoms of ADHD and OCD worse. And by the same token, living with the symptoms of these conditions can increase your anxiety to unhealthy levels.

In some cases, ADHD and OCD may lead to depression.

People with both conditions also feel intense surges of anger and persistent irritability, which can sometimes provoke aggressive behavior.

Both are associated with sleep problems

Some studies show that as many as 70 percent of people with OCD also have insomnia and other sleep disorders.

Similarly, people with ADHD often experience:

  • restless leg syndrome
  • disrupted circadian rhythms
  • obstructive sleep apnea
  • insomnia

When you don’t get enough good sleep, the symptoms of OCD and ADHD may get worse or be harder to tolerate.

Both are associated with gastrointestinal (GI) issues

Studies show that people with OCD are more likely than the general population to experience irritable bowel syndrome. People with ADHD are also more likely to have chronic constipation and irritable bowel syndrome.

Both may be caused or worsened by trauma

A growing body of research looks at the connection between childhood trauma and the emergence of developmental conditions like ADHD and OCD.

A history of childhood trauma is common among people with an OCD diagnosis.

And ADHD symptoms in children, which become ongoing symptoms in adults, can be brought on by traumatic events, especially child abuse and neglect.

Despite the similarities, the two disorders are different in important ways. A misdiagnosis can mean you end up with a treatment plan that either doesn’t help or makes your symptoms worse.

The basic nature of the disorders is different

ADHD is considered an externalizing disorder, which means problems arise because of the way the person with ADHD responds to and interacts with their environment.

OCD, on the other hand, is considered an internalizing disorder. Someone with OCD reacts to stressful events internally — with obsessive thoughts and the compulsions that help them feel a sense of control over them.

They show different effects on brain activity

Even though the frontostriatal area of the brain is the location of the problem in both disorders, the conditions show very different patterns of activity in that circuit.

Functional MRI images and other brain scans show that people with ADHD have very low activity in the frontostriatal region, while people with OCD have too much activity there.

They may involve different levels of risk tolerance

People with a certain subtype of OCD may avoid risks and uncertainty. Studies show that people who have more doubt and checking behaviors may be indecisive or may avoid risks because they’re overly concerned that they could cause harm.

By contrast, research has shown that people with ADHD may be more likely to behave in risky ways. Researchers say some of the reasons people with ADHD may be inclined to take risks include:

  • enjoying the sensations involved
  • underestimating the possible consequences
  • believing the benefits outweigh the risks
  • not wanting to wait for a safer alternative

Experts suggest that if you’re trying to decide whether a condition is OCD or ADHD, it’s a good idea to look closely at whether the individual has a tendency to be impulsive and take risks.

OCD compulsions might challenge a person with ADHD

For most people with OCD, compulsions have to be carried out consistently, and according to precise rules. That kind of strict routine, which could often involve paying close attention to details, might be difficult for a person with ADHD.

In fact, some experts say that if you’re trying to decide whether ADHD or OCD is the correct diagnosis, examining the complexity of rituals might be a good way to tell the difference.

Maybe.

On one hand, researchers who have studied the shared neurological and biological links between the conditions say between 8 percent and 25.5 percent of people may have a dual diagnosis — both ADHD and OCD at the same time.

But some researchers think having both at the same time would be rare or highly unlikely.

These researchers think that because the effects of the disorder can look so similar, the dual diagnosis rates might actually be inflated. They suggest that the demands of OCD might cause an “executive function overload” with symptoms that look a lot like the ones caused by ADHD.

A small 2019 study seems to support the idea that ADHD is often misdiagnosed in people with OCD.

A group of children who were diagnosed with both conditions were treated only for OCD. As their OCD symptoms went down, so did the inattention, hyperactivity, and impulsivity. Researchers concluded that OCD may have created ADHD-like symptoms.

ADHD is typically treated with a combination of:

Treatment of OCD usually consists of these therapies in combination:

Understanding your diagnosis — and making sure you haven’t been misdiagnosed — is really important. That’s because the medications used to treat one disorder don’t necessarily help with the other.

In fact, stimulant medications such as methylphenidate, prescribed for ADHD, have been known to cause obsessive-compulsive symptoms in rare cases.

For some people, ADHD symptoms improve as they get older, especially if they receive treatment. ADHD can persist into adulthood, though.

Doctors say that around half of those diagnosed with ADHD as children won’t have symptoms as adults. Around 25 percent may have symptoms but not severe enough to warrant medical treatment.

OCD usually comes and goes throughout your lifetime. Doctors say that among people who are diagnosed with OCD as children and who receive treatment, around 40 percent go into remission when they become adults.

OCD and ADHD can sometimes look alike. These two conditions can have similar symptoms such as inattention and cause similar problems at school or work. They’re also associated with:

  • anxiety
  • anger
  • depression
  • sleep problems
  • GI problems

Although people are sometimes diagnosed with both conditions at the same time, it may be more likely that OCD causes ADHD-like symptoms. Similar psychotherapy techniques can be used to manage both conditions, but the medications used to treat them are different.

If you have symptoms that could be either OCD or ADHD, it’s important to get a clear diagnosis as early as possible so you can put the right treatment plan into place.