Attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD) are among the most commonly diagnosed neuropsychiatric disorders. The two conditions, which have overlapping symptoms and are thought to share underlying deficits, also have substantial comorbidity rates. Despite this prevalence and documented overlap, ADHD is often missed in patients with OCD — and vice versa — often due to symptom presentation.
To ensure an accurate diagnosis and effective treatment, clinicians must understand the unique interplay between OCD and ADHD, including how ADHD tends to present in patients with OCD. They must also acknowledge common barriers to proper assessment, as well as the most frequent diagnostic errors. Finally, while a strong understanding of similarities is helpful, also fundamental is a solid foundation on the innate differences between OCD and ADHD.
What Is OCD?
OCD, as suggested in the name, is characterized by having obsessions and/or compulsions.
Obsessions can include recurrent, persistent thoughts, visions, and impulses that are experienced as intrusive and inappropriate, and which cause marked anxiety and distress to the individual. Other hallmarks of OCD obsessions include:
- Thoughts, impulses, and mental images are not simply excessive worries about real-life problems.
- The individual often attempts to ignore or suppress such thoughts, impulses, or images, or to neutralize them with some other thought or action.
- The individual recognizes that the obsessive thoughts, impulses, or images are a product of their own mind (not imposed from without as in thought insertion)
Compulsions can include repetitive behaviors (e.g., hand washing, ordering objects, checking) or mental acts (e.g., praying, counting, repeating words silently) that the individual feels driven to perform in response to an obsession, or according to rules that must be applied rigidly.
The repetitive behaviors or mental acts are aimed at preventing or reducing distress, or at preventing some dreaded event or situation. However, these behaviors or mental acts either are not connected in a realistic way with what they are designed to neutralize or prevent, or they are clearly excessive.
The OCD spectrum covers a collection of disorders and conditions that have a genetic, underlying trait of obsessionality and compulsivity. They include:
OCD and ADHD: Comorbid Considerations and Characteristics
OCD-ADHD Prevalence and Background
The comorbidity of ADHD and OCD is much more common than generally thought. Most research has studied the prevalence of ADHD in patients with OCD rather than the inverse, with diagnosis rates mostly falling around 30 percent.1
Comorbid OCD and ADHD enhance the symptoms of each other, though the presence of OCD may attenuate hyperactivity in some ADHD patients. OCD also has an earlier onset when ADHD is present.
Research reveals abnormal activity in certain regions of the brain for both ADHD and OCD. OCD is associated with increased activity in frontal and striatal regions. However, ADHD is associated with decreased activity in similar regions.
Genetically, dopaminergic genes are implicated in ADHD, while OCD is linked to serotonergic genes. The two disorders are also heritable. Family history studies show an OCD-ADHD association – compared to an individual without ADHD, an individual with ADHD is more likely to have someone in their family with OCD.
How ADHD Presents in OCD
Comorbid ADHD often gives rise to certain conditions and presentations under the OCD umbrella, including
- Pure obsessionality (Pure-O), which refers to individuals with OCD who have the obsessive thoughts component, but not the compulsive behaviors. (Pure-O, while in the family of OCD disorders, is often misidentified as anxiety)
- Tics and Tourette’s disorder, both characterized by impulsivity
Hoarding in Patients with ADHD and OCD
Recent research has linked hoarding behaviors to poor executive function, which is also at the core of ADHD. Hoarding can also look different when ADHD is present compared to OCD alone.
- Acquisition differences: Many hoarders with ADHD may acquire material due to a cycle of impulse buying. In classic OCD, on the other hand, the individual tends to save items, but impulsive behavior is not a problem.
- Ego dystonic vs. ego syntonic: Individuals with ADHD who have hoarding issues tend to be bothered by it – the behavior is often seen as inconsistent and unacceptable to their attitudes and sense of self (ego-dystonic). The clutter may also distract the individual with ADHD and even aggravate their symptoms. In contrast, individuals in the classic OCD spectrum are not as bothered by clutter (ego-syntonic).
- The motivations behind hoarding are different. Individuals with ADHD tend to be driven to hold on to items in case they are needed at a later time, and to save some “executive bandwidth.” On the OCD-side, these individuals tend to be motivated by the idea of not ridding oneself of things. Objects also tend to hold much sentimental value.
- Sense of morality and personification of objects: Individuals with OCD tend to equate throwing things out with wastefulness, and thus an attack on their character. In the most severe cases, individuals also tend to personify objects.
Body-Focused Repetitive Behaviors in Patients with ADHD and OCD
With ADHD, the function of BFRB is mainly to provide stimulation and arousal:
- A repetitive behavior can start with a distraction the individual is rejecting, like a blemish on the face or an uneven nail.
- The sensory nature of these behaviors can be very appealing for individuals with ADHD, and can also provide some stress relief as well as a fidget for focus.
- A behavior can be goal-oriented and coupled with accomplishment (like hair pulling), which can be reinforcing for people with ADHD.
OCD and Executive Functions
OCD is also an executive functioning disorder. When an individual has obsessive thoughts and compulsions, it leads to executive overload, leaving little room to attend to anything else. Compared with ADHD, however, the reasons behind the executive dysfunction are different. Individuals with OCD experience the following:
- Difficulty with planning and with working memory deficits, due to trouble filtering out irrelevant data while feeding a need for completeness
- Selective attention deficit to what is threatening or distressing. With ADHD, attention is directed to what is stimulating
- Impaired inhibition as an element of compulsivity
- Decision-making problems due to excessive over-thinking, compared to individuals with ADHD who may be more impulsive
- An inflated sense of responsibility and perfectionism, which can make taking actions and making decisions much more profound than they need be
OCD and ADHD: Diagnostic Concerns
It is helpful to think of OCD and ADHD as opposites on a spectrum, where similar, overlapping behaviors and symptoms are explained by contrasting drivers. But this also explains why ADHD is routinely missed in patients with OCD, and vice versa.
Why ADHD is Missed in OCD Patients
- ADHD is rarely assessed in clinical settings, especially in adults. A patient hospitalized for an episode, for example, may be assessed for a history of mood and anxiety disorders, but seldom for ADHD.
- ADHD and OCD symptoms can intertwine, even though the basis and motivation for the behaviors may differ.
- Myths and stereotypes about ADHD (hyperactivity, school performance, etc.) can lead to bias, especially against females and adults.
- Perceived compulsions might be based in ADHD more than OCD, as individuals with ADHD often have to create specific environments and structures to function.
- Distractibility can be seen as a positive in light of obsessive thoughts and compulsions.
- Sensory sensitivity and defensiveness could be mistaken for perfectionist tendencies.
- Hyperfocusing could be mistaken for over-focusing, which is very different.
Why OCD is Missed in ADHD Patients
- Myths about OCD (that the condition only relates to hygiene and cleanliness, for example) can make for a simplistic, inaccurate picture.
- Over-focusing can be mistaken for hyperfocus, and can sometimes be reinforcing for people with ADHD.
- Individuals with OCD often feel shame around their “irrational” symptoms, so they are less likely to discuss them in clinical settings.
- Delays and incomplete tasks can be mistaken for lack of follow-through/cognitive fatigue.
- Need for perfectionism can be labeled as sensory defensiveness, executive dysfunction, and/or stubbornness.
OCD and ADHD: Treatment Considerations
Patients with OCD and ADHD likely need a combined pharmacotherapy treatment plan comprising both SSRIs and stimulants to treat both disorders. While the medications do not have to interact with one another, there can be significant reactions. Stimulant treatment for ADHD, for example, may exacerbate OCD symptoms. As stimulants increase attention and focus, they may also lead an individual with comorbid OCD to focus more on the obsessive thought. However, there are cases when stimulants can help treat OCD, especially if symptoms are triggered by inattentiveness and other ADHD symptoms. The same can apply to SSRIs for OCD – when symptoms are in check, that tends to calm the ADHD.
Untreated, unmanaged ADHD may adversely impact OCD treatment, which is why it’s important for clinicians to assess for ADHD.
Exposure Plus Response Prevention (ERP) is the first-line treatment for OCD. It involves exposure to the obsessive thoughts that create anxiety, and inhibiting the compulsive behavior associated with the trigger. With OCD and ADHD:
- Coaching the patient is essential for motivation and accountability
- Therapy may need to begin with a high-stress trigger due to a high stimulus threshold
- Distractibility may delay anxious feelings during exposure, which needs to be accounted for
- Self-directed ERP should be planned with specific dates and times to promote follow-through
- Patients can be expected to miss sessions, show up late, or have a hard time paying attention. This can easily be misconstrued for resistance to treatment
- Therapy sometimes causes a phenomenon in patients where decreasing OCD symptoms may lead to the appearance of other symptoms or even ADHD impulsivity
The content for this article was derived from the ADDitude Expert Webinar “The OCD-ADHD Link: What You Should Know When You Have Both” [Video Replay & Podcast #343] with Roberto Olivardia, Ph.D., which was broadcast live on February 11, 2021.
OCD and ADHD: Next Steps
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1Geller, D. A. et al (2002). Attention-deficit/hyperactivity disorder in children and adolescents with obsessive compulsive disorder: Fact or artifact?. Journal of the American Academy of Child & Adolescent Psychiatry, 41, 52-58.
Updated on March 18, 2021