OCD
Intrusive thoughts: when they are normal, when they are OCD, and how they differ from the busy ADHD mind
Intrusive thoughts are common. When they point to OCD, when to ADHD and when to neither: a plain explanation from a psychiatrist.
Short answer
Almost everyone has unwanted thoughts or images that pop up without being invited. On its own, that is not an illness. It becomes a problem when the thought frightens you, makes you check or seek reassurance again and again, and eats up your time. That pattern fits obsessive-compulsive disorder (OCD) better. In ADHD the mind usually jumps from topic to topic without getting stuck on one fear. The two can look alike, which is why a careful assessment matters.
What intrusive thoughts are
They are thoughts, images or urges that arrive uninvited and often clash with who you are. For example: “what if I push someone?”, “what if I left the cooker on?”, or a blasphemous or sexual image that shocks you.
In an international study of 777 university students from 13 countries, including Greece, 93.6% reported at least one such thought in the previous three months. Doubts were the most common; thoughts that cause disgust, such as sexual or blasphemous ones, were the least common. The sample was students, not patients, so it shows how common the thoughts are, not how many people have OCD.
When it is OCD
OCD is much rarer than the thoughts themselves. In a large US population study, more than 1 in 4 people reported an obsession or compulsion at some point in their life, but only about 2 in 100 had full OCD at some point.
The difference is not the content of the thought. It is what the person does with it:
feels intense anxiety, guilt or disgust
tries to “switch it off”, check it or neutralise it (checking, counting, praying, mental reviewing)
asks others or the internet for reassurance
avoids places, people or objects
all of this takes time or disrupts work, relationships and sleep
In my practice I often explain that a catastrophic thought is a symptom of anxiety, not madness, and that what you feel is not proof of reality. The fear that “because I thought it, I might do it” is exactly the mechanism of OCD, not a sign of danger.
When it looks like ADHD, and how it differs
Many adults with ADHD describe a mind that “never switches off”. This can be confused with intrusive thoughts. Some useful differences:
Content: in OCD, a few repeated themes that frighten; in ADHD, many different topics, ideas and plans.
Feeling: in OCD, fear, guilt, disgust; in ADHD, restlessness, boredom, enthusiasm.
What the person does: in OCD, checks, re-checks and seeks reassurance; in ADHD, leaves things half-done, forgets and rushes.
Relationship with risk: in OCD, excessive caution and avoidance; in ADHD, often less caution than needed.
The research literature warns that OCD symptoms, such as poor concentration because the mind is full of obsessions, can be misdiagnosed as ADHD. That is why an ADHD assessment should actively look for OCD, anxiety and depression too. The two conditions can also coexist, but reported rates in adults vary widely between studies.
In an adult ADHD assessment I start with the history from childhood and a structured interview, and then check for other conditions that can look similar or coexist, including OCD and anxiety. The question that often separates the two is simple: “Does the thought frighten you, or does it just distract you?”
What helps and what does not
Trying not to think the thought does not help. It usually comes back stronger.
Constant reassurance does not help. It brings relief for a while, then you need more.
Avoidance feeds fear. OCD treatment is based on gradual exposure to what you fear, without the compulsion that usually follows. More about treatment on the page Obsessive-compulsive disorder.
If the main difficulty is distraction, disorganisation and impulsivity since childhood, see the page Adult ADHD.
When to seek help
The thoughts or checking take more than a little time each day, or stop you working, sleeping or being with people.
You avoid things you used to do without a second thought.
You are not sure whether it is OCD, ADHD, anxiety or something else.
Safety: If your thoughts are not unwanted but you feel you want to harm yourself or others, seek help immediately: 112, 166 (EKAB ambulance) or the Klimaka suicide prevention line 1018.
Book a psychiatric assessment, at the practice in Trikala or online.
Sources
Radomsky AS et al. Part 1—You can run but you can’t hide: Intrusive thoughts on six continents. J Obsessive Compuls Relat Disord. 2014;3(3):269-279. https://doi.org/10.1016/j.jocrd.2013.09.002
Ruscio AM, Stein DJ, Chiu WT, Kessler RC. The epidemiology of obsessive-compulsive disorder in the National Comorbidity Survey Replication. Mol Psychiatry. 2010;15(1):53-63. https://doi.org/10.1038/mp.2008.94
Abramovitch A, Dar R, Mittelman A, Wilhelm S. Comorbidity between ADHD and OCD across the lifespan: a systematic and critical review. Harv Rev Psychiatry. 2015;23(4):245-262. https://doi.org/10.1097/HRP.0000000000000050
Abramovitch A, Dar R, Hermesh H, Schweiger A. Comparative neuropsychology of adult OCD and ADHD. J Neuropsychol. 2012;6(2):161-191. https://doi.org/10.1111/j.1748-6653.2011.02021.x
