It is pretty common knowledge that OCD coexists with several other disorders, including other anxiety disorders and Major Depressive Disorder (MDD). Many also recognize there are crossover symptoms of OCD-like behavior and several other disorders. Autism Spectrum Disorders and ADHD are among those. Some research also suggests that there is an overlap of ADHD and OCD among people who engage in hoarding behaviors.
Causes
OCD and ADHD are strange bedfellows. Both are caused by problems in the frontal lobe, but ADHD is caused by under-activity (not enough dopamine and norepinephrine) in the brain, and OCD is due to overactivity (too much serotonin). Although the different types of ADHD present very differently, all types are believed to be caused by low levels of dopamine and norepinephrine in the brain. The person with the hyperactive type of ADHD that is fidgety, restless, impulsive, and careless would appear to be the opposite of a person with OCD, generally more cautious, focused, and attentive. People with the inattentive type of ADHD are often distracted, disorganized, day-dreamy, and forgetful. Again, not your stereotypical OCD traits. Those who have the combined type of ADHD (about 70%) have symptoms of both.
Misdiagnosis
These two disorders often get confused when a child (or adult in a work setting) with OCD has trouble in school. After all, ADHD, which causes problems with executive functioning (organization, planning, reasoning, prioritizing, executing projects, following through with work, etc.), wreaks havoc in the classroom. A child with OCD who spends a lot of time ordering, arranging, or checking their books, supplies, and handwriting may appear to be having problems with executive functions when in fact, they are simply trying to get or keep things on the desk in the proper place. Understanding what motivates the child’s (or adult’s) behavior is key to a proper diagnosis. ADHD can result in OCD-like coping skills. A child or adult who has trouble getting organized or who are easily distracted may spend an inordinate amount of time arranging, ordering, and cleaning things. Sometimes that is procrastination, a typical ADHD trait, but it may be an ADHD coping-skill. Many people with ADHD become over-stimulated by the clutter and disorganization in their environment. This often results in anxiety, or simply shutting down. As a result, they may learn strategies to prevent clutter and disorganization that look like OCD behaviors, ie. arranging, ordering, checking. With regard to proper diagnosis, it is important to remember that ADHD is present across all domains; OCD is generally very specific with regard to obsessive thoughts and compulsive behaviors. It is also worth noting that not all people with OCD have the type related to fear of germs and cleaning. In fact, most do not have spotless homes or lockers. Although ADHD was once believed to affect only children, the research has finally caught up with reality; in 2013 the DSM-5 moved ADHD from the category of “Disorders Usually Diagnosed in Infancy Childhood, or Adolescence” to that of “Neurodevelopmental Disorder,” recognizing that many continue to have symptoms into adulthood. It was once believed to largely disappear after puberty.
Treatment
About 30% of people with ADHD have co-occurring anxiety disorders, including OCD. Those who have problems with low dopamine and/or norepinephrine and high levels of serotonin may indeed have both OCD and ADHD. In these cases, it is extremely important to treat both disorders. However, doing so requires skill and patience. Research also suggests that co-occurring OCD and ADHD is associated with an earlier onset of OCD symptoms. While the treatment for OCD with SSRI is not usually contraindicated in ADHD (some estimate up to 50% of people with ADHD also have depression), stimulant medications used to treat ADHD can exacerbate OCD symptoms with very serious outcomes. Prescribers often treat the symptoms that are causing the most problems first. For those with both disorders, there are non-stimulant medications for ADHD that may have less impact on OCD symptoms. Treatment for both OCD and ADHD should include medication management, therapy, and self-help.
