ADHD vs OCD
OCD vs. ADHD
The conversation about ADHD and OCD is perhaps better situated as an AND conversation rather than a VS. conversation.
They co-occur at high rates. When one is present, it can be difficult to spot the other. At times ADHD may be misdiagnosed as OCD, or OCD may be misdiagnosed as ADHD, or one is diagnosed while the other remains missed.
Interestingly, they appear as opposite conditions in some ways as these conditions lay at opposite ends of the impulsive-compulsive continuum. And so, the co-occurrence of these conditions is a perplexing phenomenon. Furthermore, although these conditions are distinct, they also share several overlapping traits, making them difficult to distinguish.
Misdiagnosis or Missed Diagnosis?
It is more likely that a child with OCD is mistakenly diagnosed with ADHD than the other way around regarding misdiagnosis. The other potential misdiagnosis is when both conditions are present, and one condition is missed. For example, a child may have both and have their OCD diagnosed while the co-occurring ADHD remains missed or vice versa.
Before getting into the details of overlapping traits and how to spot the difference, let’s first do a re-fresher on all things ADHD and all things OCD.
ADHD Overview
ADHD is classified as a neurodevelopment condition, meaning the onset occurs during the developmental period (typically early childhood) and has a strong genetic component.
The parts of the brain that regulate emotions, attention, and focus are impacted in the context of ADHD. ADHD is characterized by persistent inattention, hyperactivity, and impulsivity (American Psychiatric Association 2015).
The Criteria for diagnosing ADHD include:
the presence of inattention
impulsivity, and hyperactivity (or just inattention in the case of ADHD-inattentive type)
The traits must interfere with daily functioning in at least two contexts (for example, home and school or work and home) (American Psychiatric Association, 2000). Some common symptoms of ADHD include:
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
While present from birth, ADHD may not be diagnosable until demands exceed capacity. And many children develop sophisticated compensatory strategies to offset areas of struggle. In these cases, it may be even later in life that the person’s ADHD is recognized.
Prevalence Rates of ADHD
ADHD has a higher prevalence than OCD and is overall one of the most common psychiatric disorders, with a worldwide prevalence of 5.2 % among children and adolescents (Polanczyk et al. 2007). Based on the (CDC), current estimates estimate that 6.1 children in the U.S. are diagnosed with ADHD, approximately 9.4% of children, making ADHD one of the most commonly diagnosed developmental disorders in the U.S.
OCD Overview
OCD is the world’s fourth most common psychiatric disorder. There is a lifetime prevalence of 2–3%. OCD symptoms typically emerge during childhood or adolescence.
Symptoms often first appear in childhood, and typically peak around age 11 and in early adulthood. People with OCD commonly have co-occurring psychiatric conditions, ADHD being one of the most common co-occurring conditions (Brem et al., 2014).
Obsessive-Compulsive Disorder (OCD) is characterized by two primary symptoms: obsessions and compulsions.
Obsessions are characterized by recurrent, intrusive, and distressing thoughts. These thoughts often create anxiety, at which point the person often engages in compulsions (rituals or behaviors) which function to “neutralize” the anxiety associated with the obsessive thoughts. To meet the criteria for OCD, these thoughts must be excessive and distressing.
Obsessive and intrusive thoughts tend to cluster around similar themes. Some common obsessions include:
Fear of contamination
Worries about having left appliances on or doors unlocked
Fear of acting in shameful or humiliating ways
Discomfort with things being out of order
Sexual imagery
Hypochondriac and health anxiety
Excessive thoughts regarding religion/guilt/shame and purity
Some common compulsions include:
Excessive cleaning and handwashing,
Repeating checking doors, locks, appliances
Rituals designed to ward off contact with superstitious objects
Arranging and rearranging objects
Using prayers or chants to prevent bad things from happening
Hoarding
Source Brem et al., 2014
Co-Occurrence of OCD and ADHD
Both conditions are classified as neurodevelopmental disorders with onset in childhood, share genetic overlap, and co-occur at high rates.
Studies looking at co-occurrence show a great deal of variance, so it can be challenging to gain an accurate sense of how commonly these conditions truly co-occur. Below is a summary of some of the recent studies:
8-25% of people with OCD also have ADHD (Brem et al., 2014)
In a study involving 155 OCD-affected individuals (age 4-82), 11.8% met definite criteria for ADHD, and an additional 8.6% had probable ADHD (a total of 20.4%). Those with ADHD were more likely to have hoarding disorder (41.9% compared to 29.2 of non-ADHD people with OCD) Sheppard et al., 2010:
A study involving 94 children and adolescents with OCD found that 25.5% had co-occurring ADHD Masi, 2006. In the second study in 2010, Masi et al. found that 17.1% had co-occurring OCD-ADHD (Masi, 2010).
Geller et al. found strong familial links between ADHD and OCD with Relatives affected with ADHD had a significantly elevated risk for OCD compared with relatives unaffected by ADHD (7.4% vs. 1.3%) (Geller et al., 2007)
ADHD is the most common co-occurring condition among early-onset OCD (Brem et al., 2014)
Treatment Implications for Co-Occurring ADHD and OCD
ADHD is associated with earlier onset of OCD symptoms and poorer response to treatment Masi, 2010
Co-occurring ADHD/OCD is associated with earlier onset of OCD symptoms, more severity of OCD symptoms, and more treatment resistance (Walitza et al., 2008).
ADHD rates were elevated in those with childhood-onset OCD, and strong relationship between hoarding and ADHD. Sheppard et al., 2010
Overlapping Traits
Work and School Difficulties
Both conditions can contribute to school and work difficulties-- impacting grades, attendance, and performance.
For ADHD, this is often attributed to time blindness, difficulty with regulating attention and focus, and executive functioning difficulties.
In the context of OCD, obsessions and compulsions can make attention, focus, and following through on tasks difficult. A person may also struggle with timeliness and time management if they spend copious amounts of time engaging in compulsions.
Sensory Sensitivities
Children with OCD are more intolerant of sensory stimuli (Hazen et al., 2008). Sensory processing sensitivities (particularly oral and tactile hypersensitivity) were linked with OCD symptoms later in life (Dar et al. 2012).
Similarly, sensory sensitivities are often present with ADHD. Difficulties modulating sensory input and hyper and hypo-responsiveness to sensory stim.
Intrusive Thoughts
Intrusive thoughts are often present in the context of OCD (as part of obsessions). Intrusive thoughts are also more common for ADHDers (Abramovitch and Schweiger, 2009).
Attention
Both conditions impact a person’s ability to focus and pay attention. Both may appear aloof or distracted, and it can impact work and academic performance.
Difficulty regulating attention is a key component of ADHD. For ADHD sustaining attention over a prolonged period of time (outside of an area of high interest) is quite difficult. This is related to under-activity of the prefrontal cortex in ADHD. ADHD brains are highly distractible, and their brains will be pulled by extraneous stimuli in the environment.
In the context of OCD, a person may struggle with attention regulation for different reasons. A person can become preoccupied with obsessions or completing rituals which makes it difficult to focus and pay attention to the task at hand or the person speaking.
Or a person. with OCD may experience executive functioning overload secondary to obsessions and intrusive thoughts, which lead to inattention.
Skin-Picking/Hair-Pulling
While skin-picking and hair-pulling are typically associated with OCD and classified as an obsessive and compulsive-related disorder, it can also occur in the context of ADHD. Skin-picking, hair-pulling, and nail-biting may be related to anxiety, sensory stimulation, and impulsivity.
Bernardes et al., 2018 found that treatment with a stimulant helped reduce skin picking behavior in a case study of an ADHD woman. They suggest that decreasing impulsivity and increasing attention (through medication) may help with ADHD skin-picking.
Mood Disorders and Self-Harm
Both ADHD and OCD have high rates of co-occurring anxiety and depression. Similarly, self-harm is associated with impulsivity (ADHD) and compulsions (OCD).
ADHD girls particularly are at elevated risks for self-harm, which is related to difficulty regulating emotions and impulsivity.
Similarly, self-harm is elevated among people with OCD. It can be both a response to OCD distress or a subtype of OCD (McKay and Andover).
Eating Disorders
Both groups have elevated rates of disordered eating and eating disorders. Body dysmorphia and eating disorders are associated with OCD. In one study of 237 females with eating disorders (84 with anorexia and 153 will develop bulimia), 29.5% had OCD. And OCD was associated with having a long history of eating disorders (Milos et al., 2002). OCD rates were similar among people with anorexia and bulimia.
Eating disorders are also common among ADHD girls. Biederman et al., 2007 found that ADHD girls were 3.6 more likely to have an eating disorder. ADHD girls were 5.6 times more likely to have bulimia than the general population Biederman et al., 2007. Bleck et al., 2015 found similar findings among ADHDers (4.2% prevalence rate compared to 2.0% in the general population).
Sleep
Both conditions are associated with sleep issues. Approximately 70% of people with OCD struggle with sleep difficulties (Nordahl et al., 2018).
Sleep issues are also common among ADHDers; approximately 25-50% of people with ADHD struggle with:
Insomnia
Circadian rhythm sleep disorders
Narcolepsy
Restless leg syndrome
Sleep-disordered breathing
(Source: Wajszilber et al., 2021)
Nightmares and insomnia are also common among ADHD children (Grünwald and Schlarb, 2017). And up to 70% of children with ADHD have sleep difficulties (Sciberras, 2020).
GI Issues
GI Issues Both ADHD and OCD are associated with GI issues. Both ADHDers and people with OCD are more likely to experience irritable bowel syndrome (IBS).
The prevalence of IBS was shown to be 47.6% among OCD patients compared to 4.5% in control populations (Turner et al., 2019). ADHD was also associated with GI issues and symptoms (Kedem et al., 2020).
Why are These Commonly Misdiagnosis?
It is more likely that a child with OCD is mistakenly diagnosed with ADHD than the other way around. The other potential misdiagnosis is when both conditions are present, and one condition is missed. For example, a child may have both and have their OCD diagnosed while the co-occurring ADHD remains missed or vice versa.
How OCD can look like ADHD
Abramovitch et al., 2011) have proposed the “executive function overload” model to understand the presence of inattention and focus difficulties among children with OCD. Executive overload happens when obsessive-intrusive thoughts create an executive overload which can then cause symptoms that mimic ADHD.
Executive overload occurs when a person’s brain is overwhelmed with intrusive thoughts; their executive functioning becomes so taxed (with the thoughts and with potential internalized rituals or compulsions to respond to these thoughts) that their executive functioning becomes overloaded, leaving the person with limited capacity to focus and direct their attention to their external environment. it is difficult for the person to attend to details, focus and pay attention.
This is one pathway in which OCD children may be misdiagnosed with ADHD. This child may appear not to listen and have difficulty following directions or completing tasks. This may cause the child to look like they have ADHD, particularly if it is causing difficulties at school. Within this conceptualization, it would be expected that ADHD-like symptoms would also improve as a person’s OCD is treated.
One study involving 50 adolescence assessed OCD and ADHD-inattentive symptoms at the beginning of treatment for OCD. They found that those whose OCD symptoms decreased also experienced a decrease in ADHD inattention symptoms (Guzick et al., 2017).
How ADHD can look like OCD
While perhaps less common, a person with ADHD may be misdiagnosed with OCD. A person may develop sophisticated compensatory strategies to offset their attention and focus difficulties. For example, a person may become obsessively particular about their external environment (to manage focus issues).
The ADHD person may also engage in skin-picking or hair-pulling; however, rather than being an OCD behavior, this happens in the context of sensory stimulation/impulsivity. Such individuals may present with OCD, whereas it is underlying ADHD causing these difficulties.
Missed Diagnosis
The third form of misdiagnosis (or rather missed diagnosis) is when the child or adult has both conditions, but only one is diagnosed. Given the high percentage of people with OCD who also have ADHD, it is recommended that ADHD be screened for when a child is diagnosed with OCD Masi, 2006.
How to Spot the Difference
In addition to screening for both conditions, here are some other things that may help discern the difference.
1) Assess the level of impulsivity and risk-taking. Those with OCD only tend to be risk-averse and will not intentionally seek out thrill and excitement sensory experiences, while those with ADHD are more likely to be sensory/thrill-seeking and risk-taking.
2) Examine the complexity and function of rituals. In the context of OCD, rituals (compulsions) will serve a function (to neutralize the obsession); behavior that looks like a ritual in the context of ADHD may be more related to hyperactivity/stimming.
Implications for Clinicians
Medication Considerations
One difference between these conditions is the neurotransmitters involved. While dopamine dysregulation is associated with ADHD, serotonin dysregulation is associated with OCD which has implications for pharmaceutical intervention (Brem et al., 2014).
Furthermore, if a child with OCD is misdiagnosed with ADHD and placed on a stimulant, they may experience an exaggeration of symptoms. Several studies suggest that stimulant therapy may exacerbate obsessive-compulsive thoughts and behaviors in children with OCD.
Consider Routine Screening of ADHD
Screening for ADHD should be performed in patients with OCD, as these patients and their parents are frequently unaware that the impairment may be partly due to comorbid ADHD (Masi, 2006).
References
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