The rate of co-occurrence of ADHD and OCD has been reported to be as high as 60%.1 A question persists, however, on whether ADHD-OCD comorbidity is a true entity or whether symptoms attributed to one may be facets of a phenotype of the other. Abramovitch and colleagues2 argue that ADHD-like symptoms can manifest in persons with OCD and that this phenomenon is being misdiagnosed as comorbid ADHD-OCD. To clarify the issue, the researchers performed a systematic review of the scientific literature.
The team searched 33 years’ worth of medical literature, excluding articles that were not in English, did not base diagnoses on measures dictated by the Diagnostic and Statistical Manual of Mental Disorders, and did not provide data on ADHD-OCD co-occurrence. Forty-eight studies met inclusion criteria, representing 43 pediatric samples and 14 adult samples.
The researchers found that ADHD-OCD co-occurrence rates are highly inconsistent, ranging from 0% to 60%, particularly in pediatric studies. Most of the studies examined clinical samples although the reliable barometer for determining prevalence is nonreferred or general population samples. The wide variance was specifically seen in studies that focused on ADHD symptoms in OCD, whereas occurrence rates for studies examining OCD symptoms in ADHD (most performed in general population samples) were 3% to 7.5%. The research team, therefore, argued that a selection bias may be at play in a good deal of the scientific literature on ADHD-OCD co-occurrence.
How ADHD and OCD can co-occur is confounding, and some say that the disorders are polar opposites. ADHD is an externalizing disorder associated with impulsiveness and risk-taking behavior, mediated by dopaminergic neurochemistry. OCD, on the other hand, is an internalizing disorder associated with risk avoidance and restraint, neurochemically mediated by serotonin. Patients with OCD display frontostriatal hyperactivation whereas those with ADHD display frontostriatal hypoactivation.
The research team pointed out, however, that OCD in pediatric patients may differ neurologically from OCD in adolescents and adults. Whereas frontostriatal hypermetabolism may be present in adults with OCD, it is not in young children with OCD. In contrast to adolescent and adult OCD, pediatric OCD may be associated with decreased frontostriatal activity, which is associated with impulsive behavior as seen in ADHD. Thus, young patients with OCD may display symptoms that potentially lead to misdiagnosis of ADHD, in turn leading to inflated rates of ADHD-OCD comorbidity.
In addition, the researchers suggested that ADHD-like symptoms in patients with OCD may be attributable to executive function overload caused by obsessive rumination. Consequent neuropsychological deficits shared by ADHD can then be mistaken for ADHD, they say.
Finally, they comment that more accurate studies are sorely needed to better explain why and whether ADHD and OCD co-occur. They point out that misdiagnosis of ADHD in OCD can be particularly problematic, as stimulant therapy can significantly exacerbate OCD symptoms.
Abramovitch A, Dar R, Mittelman A, Schweiger A. Don't judge a book by its cover: ADHD-like symptoms in obsessive-compulsive disorder. J Obsessive Compuls Relat Disord. 2013;2:53-61.
Abramovitch A, Dar R, Mittelman A, Wilhelm S. Comorbidity between attention deficit/hyperactivity disorder and obsessive-compulsive disorder across the lifespan: a systematic and critical review. Harv Rev Psychiatry. 2015 Jun 6.
I agree with Dr. Abramovitch’s views on the ADHD/OCD discussion because I have evaluated dozens of children that were unable to stay focused in class due the second guessing and insecurity that are part of the OCD and they were diagnosed as having ADHD.
They came for second opinions because instead of improving with the amphetamine-like medications, they got worse and some developed side effects such as hair pulling and tics.
This follow up conversation is extremely important because the over-diagnosing of ADHD which lead to this type of mistakes, can have serious consequences for the patients due to the negative impact of all stimulants (even caffeine) on the symptoms of OCD.
It is about time that solid data debunks the fabricated prevalence of ADHD. The alleged 6-10% claimed by those that diagnose with ADHD every child that comes to their clinic is the summation of“ADHD & ODD,”“ADHD & OCD”,“ADHD & Autism”,"ADHD & Conduct Disorder”,“ADHD & Bipolar Disorder”,“ADHD and Anxiety”, etc., which in fact are“none of the above.”
I recently quit C&A psychiatry because the pervasive misdiagnosis was too painful but I still hope that some of our colleagues will put egos at rest and do what it is best for the patients.
Manuel Mota-Castillo, M.D.
Manuel @ Thu, 2015-07-09 22:08
I have a hard time considering such comorbidity exists.
Neurophysiology has to be taken into account. Checklists may become a true tragedy for patients, i frequently encounter with patients that have been on stimulants for long periods of time along with SSRI properly used for their OCD.
The tragedy is that the stimulants were prescribed by non psychiatric physicians that made an ultra rapid diagnosis of ADD using a checklist.
Jose Miguel@ Thu, 2015-07-09 21:39
This paper is very timely - thank you. As a child and adolescent psychiatrist, I come across a number of children with OCD who have been diagnosed as ADD or the two diagnoses offered together, less commonly. Clinically, if we take the time to talk with these patients and ask the right questions, or use brief but simple questionnaires such as the Leyton O.C. Scale we would be able to diagnose OCD which is an internalizing disorder characterized by guilt, depression and anxiety, and an air of secrecy because of the shame associated with it. Having seen hundreds of young children and adolescents with OCD, previously diagnosed as ADD, it is such a pity that they have not received the right treatment and have suffered longer than they needed to - their families too.
Joan HALIBURN, Australia
JOAN @ Thu, 2015-07-09 16:20
Until the research begins to ask the difficult* question of prenatal alcohol exposure when studying disorders like these (and Bipolar as well), a huge possible explanatory factor will continue to fly under the radar.
*Difficult in so many ways!
--does not lend itself to hard numbers:"Do you know if your mom drank when you were little"is about as good as we can do. But it is an essential beginning.
--brings up the delicate question of finger-pointing at moms
--confounds funding possibilities by pharmaceutical companies
Great thanks to you who will consider this possibility.
Kathryn W. Page, Ph.D.
kathryn @ Thu, 2015-07-09 15:54
Kathryn-I agree that is it imperative to ask questions regarding prenatal alcohol exposure, (along with maternal smoking) and- is most certainly is a start, especially for research purposes! My field of study/research is ADHD with a focus on the neurobiology of the disorder (e.g., hypothalmic dopaminergic abnormalities, and so on) as 'confirmation of such can provide assistance with diagnostic assessments and suggest pathophysiological-based treatments which I think could be of great value to patients with ADHD. To further your point according to molecular genetic studies, ADHD is a heritable condition and coupled biological adversity indicates that prenatal alcohol exposure and maternal cigarette smoking increases the independent risk for ADHD. Thus, I do consider this possibility and appreciate your insight!
Tamara@ Wed, 2015-08-12 23:05
Curious, I recently read a research article that suggest thyroid fluctuations in pregnancy impacts rick for ADHD. I am not sure on this possibility but consider most!
Tamara@ Wed, 2015-08-12 23:40
In terms of differentiation of symptoms, there is also the matter that adolscent and adult patients with ADHD may check things a lot, e.g."do I have my keys?""did I turn off the sprinkler?"sometimes so repeatedly as to look like patients with OCD, however this checking is confined to areas in which they have repeated experiences of having forgotten, overlooked, or misplaced mundane items or tasks. There is little of the"what if ?type fear of potential bad outcomes seen in OCD.
Jane@ Thu, 2015-07-09 14:48
Spot on! Many adult individuals diagnosed with ADHD may be the"checklist"type --especially after one is aware of the diagnosis. However, I am in agreement --as often the ADHD patient has no real sense of fear (worry /what if's) if mundane tasks on the checklist are completed at all and are frequently forgot about as the day goes on. Additionally, the ADHD patient is more likely to live life"one day at a time"or"live in the moment"which can be chaotic but there is no real sense of"fear"of what may or may not occur.
In differentiating ADHD symptoms for diagnosis purposes in adults the symptoms are pervasive and seemingly distinct as you all are aware I am sure! Research shows that adults with ADHD are more likely to have problems with his or her drivers license (speeding tickets, drivers license suspensions, court dates for speeding tickets, late inspections, drivers license registration and renewals. Next time, try asking if the potential ADHD patient has a good driving record and if he or she is good with the mail, (an easy example regarding the mail-- is when one is ready to upgrade or switch cable providers) a problem for the ADHD adult is mailing back a router, whatever it may be thus resulting in charges to the prior company. With research specializing in ADHD I can go on and on. My thought is that ADHD is a syndrome and if not diagnosed by young adulthood --the adult will have trouble functioning in life (with the exception of certain domains). Other questions to ask an adult presenting with ADHD symptoms are HOW MANY TIMES IN YOUR LIFE have you ever left your purse in a store, locked the keys in the car while running, ran out of gas, lost your phone, it is the certain repeated mistakes over years that can help to differentiate ADHD from other disorders. My thoughts are that an a patient with OCD would have a VERY hard time living as a patient with ADHD.