TL;DR
ADHD and bipolar disorder share distractibility, restlessness, impulsivity and pressured speech. The difference lies in the time pattern: ADHD is a persistent trait from childhood, mania and hypomania are distinct episodes with a clear change from the usual self. Around 8 percent of adults with ADHD, about one in thirteen, also have a bipolar disorder. The two are treated differently. That is why screening for bipolar disorder is a fixed part of our ADHD assessment, and why a positive MDQ is a question, not an answer.
Perhaps you know periods when the tempo is higher than usual: you sleep less, get a lot done and talk faster. And periods when the energy is gone. In between you are yourself, maybe a little distractible and restless, the way you remember it from your school years.
It can be hard to judge on your own whether it is ADHD, bipolar disorder or both. It is worth finding out, because the two conditions are treated differently.
Why are they confused?
Because the surface looks the same. Distractibility, increased activity, impulsivity, pressured speech, irritability and poor sleep appear in both conditions. A person in the middle of a hypomanic episode can meet most ADHD criteria on paper, and a person with ADHD can describe their life as a series of highs and lows.
And because they often occur together. Between 70 and 80 percent of people with ADHD have at least one other psychiatric diagnosis, and around 8 percent, about one in thirteen, also have a bipolar disorder. So the question is often not either-or, but which is which.
| Symptom | In ADHD | In bipolar disorder |
|---|---|---|
| Distractibility | Persistent, typically since childhood | In periods of changed mood |
| Increased activity | Chronic restlessness, "driven by a motor" | Increased energy and activity during mania or hypomania |
| Impulsivity | A trait, usually known from childhood | Escalates during episodes |
| Pressured speech | Can be present day to day | Emerges during manic or hypomanic episodes |
| Irritability | Often a low frustration tolerance | Episodic, often alongside elevated mood |
| Sleep | Trouble settling at night, tired the next day | Reduced need for sleep over several days, typically four or more, without feeling tired |
The decisive difference: episodes or traits
ADHD is a trait. It has typically been there since childhood and shows across most areas of life: work, home, relationships. It varies with sleep, stress and interest, but it does not come and go in bounded periods.
Mania and hypomania are episodes. A bounded period of several days or weeks in which you are clearly different from your usual self, and the people around you can often see it. Mood is elevated or irritable, and energy is increased. Afterwards you return to your baseline, or mood dips.
That is why one of the questions we ask in the assessment is: Has there been a period of several days when you were clearly different from your usual self, more elevated, more energetic, sleeping less and yet not tired? The answer, and especially the story that comes with it, matters more than the questionnaires.
Symptoms that belong only to mania
Some symptoms belong to mania and not to ADHD, and they are worth knowing. Grandiosity: a sense of self far beyond ordinary confidence, the feeling of being able to do anything. Reduced need for sleep: feeling rested after three or four hours of sleep, several nights in a row. People with ADHD are often tired but find it hard to settle; that is something else. A sudden surge of projects started all at once. And in severe cases psychotic symptoms such as delusions or hallucinations.
In the Danish diagnostic system the condition is called bipolar affective disorder. The latest edition of the WHO classification, ICD-11, distinguishes type I, which requires at least one manic episode of around a week, from type II, which requires at least one hypomanic episode of several days together with at least one depressive episode. Both share a dual requirement: a change in mood and an increase in activity or energy. The latter is new in ICD-11 and sharpens the criteria against ADHD, where energy is chronic, not changed.
Mixed states, rapid cycling and cyclothymia
The picture is not necessarily clean. In a mixed state, manic and depressive symptoms are present at the same time or alternate from day to day, sometimes within the same day: restless energy and black hopelessness at once. ICD-11 requires it to last at least two weeks. Mixed states are seen more often later in the course of the illness, where elevated mood has often given way to a heavy, hostile irritability. That irritability is easily mistaken for the low frustration tolerance of ADHD.
Rapid cycling means four or more mood episodes in a year. They are still episodes, with a beginning and an end. If mood shifts faster than that, hour by hour, it points away from bipolar disorder and towards something else: a mixed state, the emotional dysregulation of ADHD, or a personality difficulty.
Cyclothymia is the milder end of the bipolar spectrum: at least two years with numerous periods of hypomanic and depressive symptoms that do not reach a full episode. What separates cyclothymia from ADHD is again the time scale. Cyclothymic swings last days to weeks. The emotional reactions of ADHD last hours and usually have a trigger.
The timeline tells most of the story
Three things in the history typically decide the question. Onset: ADHD symptoms typically show before the age of 12 and continue into adult life. The first manic episode typically comes in the late teens or early adulthood, and bipolar type II is often discovered later because the hypomanic periods feel good and go unmentioned. Pattern: the mood swings of ADHD are reactive, triggered by something and over within hours. Bipolar episodes keep running on their own, even when circumstances are calm. And the view of others: family and partners often notice episodes the person normalises. That is why we involve a relative when we can.
The same time scale also helps with a third condition that often gets mixed in: emotionally unstable personality structure. Here mood shifts within hours, triggered by something in relationships. Bipolar mood shifts come from within and last days to weeks. The three conditions do not exclude each other, but they are treated differently, and so it is worth telling them apart.
What the MDQ can and cannot do
The Mood Disorder Questionnaire, MDQ, is a short questionnaire about whether you have ever had a period when you were not your usual self: 13 yes/no items about manic symptoms, one item on whether several of them occurred at the same time, and one on how much of a problem they caused. The screen is positive when all three criteria are met: at least seven symptoms, in the same period, with moderate or serious problems. You can complete the questionnaire here. It is processed locally in your browser, and the result is a screen, not a diagnosis.
The questionnaire is useful, but it has to be read with care. In a Norwegian study of 510 adults with ADHD, 50.6 percent screened positive on the MDQ against 8.3 percent of controls, while a diagnostic interview found bipolar disorder in about a third. So the questionnaire flags far more people than a diagnostic interview confirms. Across 21 studies the questionnaire catches 62 percent of true cases and clears 85 percent of those without the condition. And among outpatients without bipolar disorder, around 15 percent still screen positive, often because of anxiety, PTSD, substance use or ADHD itself.
The conclusion is simple. A positive MDQ is an instruction to the clinician to take a thorough history focused on episodes. It is not a finding in itself. And a negative MDQ does not rule everything out, which is what the next section is about. There is also no validated Danish translation of the questionnaire; the figures above apply to the English original.
When it is neither ADHD nor bipolar disorder
There is a third possibility that questionnaires do not catch. In the psychodynamic tradition, Nancy McWilliams describes a hypomanic personality structure: people who live at a persistently high tempo, charming, energetic, distractible, on to the next thing. McWilliams writes plainly that the characterologically manic person is easily assumed to have ADHD.
The difference is not on the surface but in the inner theme. The hypomanic personality is organised around losses that were not grieved: deaths, divorces, moves, broken relationships, handled by keeping going. The tempo is a defence against feeling it. The history often holds many addresses, many changes of school, friendships that ended abruptly and were not openly missed. Slowing down feels uncomfortable.
Here both the MDQ and the question about episodes fail, because there are no episodes. The high energy is the baseline, not a departure from it. The person honestly answers no to most items, and the screen is clean. What reveals the pattern is the clinical conversation about the life history: what has been left behind, and what has not been felt. That is one reason an assessment with us rests on a thorough clinical interview and not just on questionnaires. And McWilliams adds a warning that applies as much here as in bipolar disorder: the physician should be particularly careful with medication that can trigger a manic state.
Why the order matters for medication
This is one reason we take care to tell them apart. Stimulant ADHD medication can trigger mania in a person with unrecognised bipolar disorder. Antidepressants can do the same; the Danish Health Authority's 2014 national clinical guideline advises against antidepressants as maintenance treatment in bipolar disorder precisely because of the risk of tipping into mania. Conversely, mood stabilisers do nothing for untreated ADHD.
When both conditions are present, a fixed order applies: the most burdensome condition is treated first, and mood is stabilised before ADHD medication is considered. That is a medical decision. This is why a psychiatrist is part of the evaluation when the picture is complex, and why it is a good reason to ask again about episodes if ADHD medication has not worked or has made things worse.
What we do if we suspect bipolar disorder
We screen for bipolar disorder in every assessment with us, whichever pathway you have booked. It happens in the clinical interview, where we do a broad psychopathological screening. If the conversation raises suspicion of an affective disorder, we ask you to complete the MDQ, and we map a timeline of periods with elevated mood, increased activity and reduced sleep, together with a relative where possible. In an ADHD assessment the developmental interview in DIVA-5 also shows whether the symptoms have been there since childhood.
Sometimes an assessment reveals a pattern of episodes that points towards bipolar disorder. Then we do one of two things. In certain cases we continue the assessment here, with a psychologist or psychiatrist. In other cases we write a thorough clinical report that you take to your GP. Your GP can refer you to an affective disorders clinic or to Center for Visitation og Diagnostik, the Capital Region's psychiatric referral centre, so you are assessed in the public system.
The door stays open. If the public system does not confirm the diagnosis, you are welcome to continue assessment or treatment with us. And if you are diagnosed and stable in your treatment for bipolar disorder, and the team there recommends an assessment for ADHD or ADD, you are very welcome back.
If you recognise something described here, that is enough to look into it further. Read more about our ADHD assessment and what to expect from the process.
All pathways start with a clinical interview, where we also ask about mood episodes.
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Frequently asked questions
Yes. Around 8 percent of adults with ADHD, about one in thirteen, also have a bipolar disorder. When both are present, the ADHD symptoms persist between mood episodes, while the manic features such as grandiosity and reduced need for sleep disappear once mood is stable. The order of treatment matters: mood is typically stabilised before ADHD medication is considered.
Episodes or traits. ADHD is a persistent pattern, usually known from childhood, and it shows across most areas of life. Mania and hypomania are distinct periods of days to weeks in which the person is clearly different from their usual self. Grandiosity, reduced need for sleep over several days without tiredness, and psychotic symptoms belong to mania, not to ADHD.
No. The MDQ is a screening tool, not a diagnosis. Around half of adults with ADHD screen positive, and a share of them do not have bipolar disorder. A positive screen means the clinician needs to take a thorough history focused on episodes. That conversation decides the question, not the questionnaire.
It can, in people with unrecognised bipolar disorder. That is one of the reasons screening for bipolar disorder is a fixed part of our ADHD assessment, and why a psychiatrist evaluates medication when the picture is complex.
Bipolar disorder is not something we assess as a standalone pathway. If we suspect it during an assessment, in certain cases we continue the assessment with a psychologist or psychiatrist. In other cases we write a thorough clinical report that you take to your GP, who can refer you for assessment in the public system. You are welcome back afterwards, whatever the answer turns out to be.
References and further reading
- WHO (2024). ICD-11: Bipolar type I (6A60). The International Classification of Diseases, 11th revision.Criteria for manic, hypomanic and mixed episodes.
- Hirschfeld RM et al. (2000). Development and validation of a screening instrument for bipolar spectrum disorder: the Mood Disorder Questionnaire. American Journal of Psychiatry, 157(11), 1873-1875.The original MDQ and its scoring rule.
- Halmøy A et al. (2010). Bipolar symptoms in adult attention-deficit/hyperactivity disorder. Journal of Clinical Psychiatry, 71(1), 48-57.510 adults with ADHD: 50.6 percent MDQ-positive against 8.3 percent of controls.
- Wang HR et al. (2015). The validity of the Mood Disorder Questionnaire for screening bipolar disorder: a meta-analysis. Depression and Anxiety, 32(7), 527-538.21 studies: sensitivity 0.62, specificity 0.85.
- Zimmerman M et al. (2011). Psychiatric diagnoses in patients who screen positive on the Mood Disorder Questionnaire. Psychiatry Research, 185(3), 444-449.15.2 percent of 428 outpatients without bipolar disorder screened positive.
- Danish Health Authority (2014). National clinical guideline for bipolar disorder, pharmacological maintenance treatment.Advises against antidepressants as maintenance treatment because of the risk of mania.
- Schiweck C et al. (2021). Comorbidity of ADHD and adult bipolar disorder: a systematic review and meta-analysis. Neuroscience and Biobehavioral Reviews, 124, 100-123.71 studies: 8 percent of adults with ADHD have bipolar disorder, 17 percent of adults with bipolar disorder have ADHD.
- McWilliams N (2011). Psychoanalytic Diagnosis, 2nd edition, chapter 11. Guilford Press.Hypomanic personality and its confusion with ADHD.