ADHD and Bipolar Disorder: Why So Many People Get the Wrong Diagnosis

I often liken living with both ADHD and bipolar disorder to a tornado meeting a volcano. In my clinical practice, I have seen what this combination does to people’s lives, and the image holds up. When both conditions are present at once, their combined force creates something more volatile and harder to manage than either would be alone.

What makes this especially difficult is that the two conditions can look remarkably similar from the outside. Impulsivity. Mood instability. Restlessness. Sleep disruption. These features appear in both, which is why the wrong diagnosis, or an incomplete one, is so common.

Studies suggest it takes an average of seven years from first symptoms to an accurate diagnosis of bipolar disorder (Hirschfeld et al., 2003). Seven years. That is seven years of wrong or partial treatment, inadequate support, and in some cases a condition that worsens because it is being managed as something else entirely.

If you are worried about someone close to you, or if you are reading this because your own experience has never quite been explained, this piece is for you.

Why Do ADHD and Bipolar Disorder Get Confused?

What symptoms do they share?

On a surface reading, the two conditions have a great deal in common. Both can produce impulsivity that leads to poor decisions. Both disrupt concentration. Both interfere with sleep. Both cause mood to shift in ways that feel, to the person living with them and to those watching, rapid and difficult to predict.

These shared features are not coincidental. They reflect a genuine overlap in the underlying neurobiology of the two conditions. Recent research by Zhang and colleagues (2024) identified shared neurobiological bases between ADHD and bipolar disorder, which goes some way to explaining why they so often appear together and why the symptoms can be so hard to separate.

Why is it so easy to get it wrong?

Partly because most clinical assessments are cross-sectional. A clinician sees the person at a single point in time, often during a period of acute distress, and works from what they observe in that consultation. The full picture, how symptoms have evolved across months and years, may never be properly assembled.

Adult ADHD is frequently missed in people who present with mood complaints. Depression, anxiety, or an apparent personality disorder tends to be the more visible presenting concern, and the ADHD beneath it goes unrecognised. The reverse error also happens: bipolar disorder is sometimes overcalled in people with ADHD who show chronic irritability and mood reactivity, when in fact there is no clear episodic pattern that would meet diagnostic criteria.

Getting this wrong has real consequences, which is why the distinction matters.

What Is the Difference Between ADHD and Bipolar Disorder?

Is ADHD a mood disorder?

No. ADHD is a neurodevelopmental condition. It begins in childhood, it is lifelong, and it is characterised by a persistent pattern of inattention, impulsivity, and often hyperactivity. These are trait-level features, meaning they are part of how the person’s brain works across all settings and across time. They do not come and go. They are always there, to varying degrees, in the background.

Bipolar disorder is a mood disorder. It is episodic. A person with bipolar disorder may have extended periods of relative stability, and then be hit with a depressive episode, a manic episode, or a hypomanic one. These are state-level changes, distinct shifts from the person’s baseline that have a beginning and an end.

What does episodic actually mean?

This is the most clinically important distinction between the two conditions, and the one most likely to be missed in a symptom checklist.

In ADHD, symptoms are chronic. Present most days, across most settings, traceable back to childhood. The inattention in a meeting and the inattention in a conversation at home are part of the same underlying pattern. There is no clear remission, no before and after.

In bipolar disorder, mood episodes are discrete. A manic episode might last days to weeks and has a quality of being markedly different from the person’s usual self. People who know them well will often describe a recognisable change: not quite themselves. Between episodes, the person may function relatively normally.

Prof Hankir’s shorthand is useful here: if it is lifelong and constant, think ADHD. If it is episodic and extreme, think bipolar.

How does sleep tell them apart?

Sleep is one of the more reliable distinguishing features, and one that often gets overlooked. In ADHD, sleep difficulties typically present as trouble falling asleep, a delayed sleep phase, or poor sleep quality. When sleep is disrupted, fatigue follows the next day.

In a manic or hypomanic episode the picture is different. The person may sleep only two or three hours and still feel full of energy. There is a reduced need for sleep rather than disrupted sleep, and the absence of fatigue despite that reduction is a meaningful clinical signal. It points toward a mood episode, not the chronic sleep dysregulation typical of ADHD.

Can You Have ADHD and Bipolar Disorder at the Same Time?

How common is it?

Yes, and the co-occurrence is far more common than most people realise.

A 2021 meta-analysis by Schiweck and colleagues, drawing on 71 studies, found that approximately 17% of adults with bipolar disorder also met criteria for ADHD. Among adults with ADHD, the figure was around 8% (Schiweck et al., 2021). A 2025 review by Parker and colleagues noted that reported rates across studies range from 9.5% to 36%, reflecting significant variation depending on clinical setting and diagnostic method used (Parker et al., 2025).

These two conditions cluster together at rates well above what chance alone would predict. If you have bipolar disorder, there is a meaningful chance that ADHD is also part of the picture.

What does it feel like to have both?

The baseline impulsivity and distractibility of ADHD does not stop when a bipolar episode arrives. It is still there. Then, superimposed on top of it, come the extremes: the elevated or irritable mood, the grandiosity, the racing thoughts, the eventual crash into depression. The ADHD does not pause for the episode. Both are happening at once.

For someone on the outside watching this, it can be deeply confusing. The person may seem fine for a period, then suddenly unlike themselves. The inconsistency can read as a character issue or a choice, when in fact it reflects the collision of two separate and simultaneous neurological realities.

What Does Science Say About ADHD and Bipolar Comorbidity?

What are the risks of having both conditions?

The research is consistent. Having both ADHD and bipolar disorder is associated with a more severe course than having either condition alone. Studies report earlier onset of psychiatric symptoms, more frequent mood episodes, shorter periods of stability between episodes, greater difficulties with employment and relationships, higher rates of substance use, and more psychiatric hospitalisations (Comparelli et al., 2022).

Suicide risk is also elevated. Schiweck et al. (2021) noted higher rates of suicide attempts in those with both conditions, and Comparelli et al. (2022) reinforced this finding, identifying increased suicide-related outcomes when ADHD is present alongside bipolar disorder. The exact magnitude varies by cohort and is partly confounded by depression severity and substance use, but the direction of the evidence is clear. An accurate diagnosis is not just clinically helpful. In this population, it is urgent.

Is it possible they have the same disorder?

Some researchers have started to ask this question seriously. The high rate of co-occurrence, the shared genetic architecture, and the overlapping neurobiological features have led a number of scientists to propose that ADHD and bipolar disorder may not always represent two fully independent conditions. One perspective frames them as different expressions of a shared neurodevelopmental and affective vulnerability, rather than cleanly separate diagnostic categories (Strohmaier et al., 2024).

This remains an open and actively debated question. Most clinicians still treat them as distinct conditions with overlapping features, and that is the position supported by the current evidence base. But it is worth knowing that the boundaries between them are less sharp than the diagnostic categories might suggest.

ADHD Mood Swings vs Bipolar: What Is the Difference?

This is often the question at the heart of the confusion, particularly for someone trying to make sense of what they are observing in a person they love. The table below outlines the key distinguishing features across six clinical dimensions.

Key clinical differentiators between ADHD and bipolar disorder. This table is a guide to clinical thinking, not a diagnostic tool. Seek specialist assessment for an accurate diagnosis.

Why does this distinction matter so much?

Because the treatment for each condition is different. And treating one without accounting for the other can make things significantly worse.

A table like this can help a person, or someone who cares about them, arrive at a consultation with a clearer and more detailed account of what they have observed across time and across settings. That kind of longitudinal description is exactly what a thorough diagnostic assessment needs. It cannot replace clinical assessment, and it should not be used to self-diagnose. But it can sharpen the conversation.

Why Does Getting the Right Diagnosis Matter?

What happens if bipolar disorder is missed?

When bipolar disorder goes unrecognised, the person is typically treated only for the ADHD, the depression, or the anxiety that is most visible in the room. The mood disorder remains unaddressed. And an unaddressed mood disorder tends not to stay still. Episodes often become more frequent or more severe over time.

There is also a sequencing problem that has direct treatment implications. Bipolar disorder needs to be stabilised before ADHD symptoms can be safely and effectively addressed. If clinicians are not looking for bipolar disorder, that question never arises.

Can you take ADHD medication if you have bipolar disorder?

This is one of the most commonly asked questions, and the answer requires some care. The most consistent recommendation across recent clinical reviews is to stabilise bipolar disorder first, using mood stabilisers such as lithium, valproate, lamotrigine, or appropriate atypical antipsychotics, chosen according to the individual’s bipolar subtype and symptom history.

Stimulant medication, when used without a mood stabiliser in place, carries a meaningful risk of triggering or worsening manic episodes. This is the scenario most consistently flagged in the research as problematic. Once bipolar disorder is well managed, stimulant treatment can be considered cautiously and with close monitoring, particularly methylphenidate-based medications (Safren et al., 2025). But this is not a decision for primary care.

As Prof Hankir puts it: get the order wrong, and you can make symptoms worse. This is specialist territory, and it needs a psychiatrist who understands both conditions.

What Should You Do If You Are Worried About Someone?

What should you look for?

If you are concerned about someone in your life, the most useful thing you can do is observe and record. Not to diagnose, but to describe. Note how long mood changes last. Note whether they seem reactive to events or whether they arise more independently. Note what happens between the difficult periods. Note whether sleep changes in quality, or whether the person seems to need significantly less sleep but remains energised despite it.

Patterns across time are what a thorough diagnostic assessment needs. A clinician seeing someone once during a difficult week has a fraction of the information that a close family member or friend holds. That information is clinically valuable and worth bringing to the appointment.

Who is the right person to see?

A GP can be a useful starting point, and the NHS does offer referral pathways for both ADHD assessment and bipolar disorder. In practice, however, NHS waiting times for specialist mental health assessment are often lengthy, and the complexity of a presentation that involves both conditions can be difficult to navigate through standard referral routes. Disentangling ADHD, bipolar disorder, and their combination requires specialist expertise. Even family doctors may struggle with presentations this complex. A consultant psychiatrist with experience in both neurodevelopmental conditions and mood disorders is the right starting point. A thorough assessment will take in symptom history across the lifespan, collateral information from people who know the person well, and the full longitudinal course of the difficulties, not just how the person presents on a given day.

The sooner the right assessment happens, the sooner the right treatment plan can begin.

How The Private Therapy Clinic Can Help

At The Private Therapy Clinic, we work with people navigating exactly this kind of complexity. Whether you are concerned about someone you love, or whether you are reading this because your own experience has never quite been explained, we offer ADHD assessments carried out by experienced clinicians, as well as access to our consultant psychiatrists who are skilled in differentiating between conditions that overlap as significantly as these do. You can read more about both on our ADHD issues page and our bipolar disorder page.

If you are not sure where to begin, we offer a free 15-minute consultation to help you find the right path forward. Book your free consultation here.