ADHD vs Bipolar: How to Tell the Difference (and Why It Matters)

When Your Symptoms Could Be Either Thing

I am going to be upfront about something. This is one of the most important differential diagnosis topics I encounter, and it is also one of the most confusing. Because ADHD and bipolar disorder share enough surface-level similarities that even clinicians sometimes get it wrong.

If you have ever Googled "do I have ADHD or bipolar" at midnight, scrolled through symptom lists, and felt like both descriptions applied to you, you are not imagining things. The overlap is real. But the differences matter enormously, because the treatment paths are completely different, and getting the wrong diagnosis can genuinely make things worse.

I am not a psychiatrist. I want to be clear about that. What I am is an ADHD mentor who works with adults navigating the messy reality of diagnosis, misdiagnosis, and figuring out what is actually going on in their brains. And I have had enough clients come to me saying "I was treated for bipolar for years before anyone considered ADHD" (or the other way around) that I think this conversation really matters.

So let us break it down properly.

Where ADHD and Bipolar Overlap

First, the uncomfortable truth: these two conditions share a lot of features. Which is exactly why the confusion exists.

Impulsivity

Both ADHD and bipolar disorder involve impulsive behaviour. Spending sprees, impulsive decisions, saying things you regret, taking risks. From the outside, impulsivity looks the same regardless of the underlying condition.

The difference is in the pattern. ADHD impulsivity is constant. It is your baseline. You have always been impulsive. It is there on good days and bad days, in every context.

Bipolar impulsivity spikes during manic or hypomanic episodes. Between episodes, impulsivity may be relatively normal. During a manic episode, it can escalate dramatically.

Racing Thoughts

This is one of the most commonly confused symptoms. People with ADHD describe their minds as constantly buzzing, jumping between ideas, unable to settle. People in a manic or hypomanic episode describe almost identical experiences.

Dr Russell Barkley has written extensively about how ADHD affects internal mental activity. He describes ADHD as a condition of "too much mental noise," where the brain struggles to filter and prioritise its own thoughts. This is constant and lifelong.

In bipolar disorder, racing thoughts emerge as part of a mood episode. They have a beginning, a peak, and an end. They are not your normal.

Emotional Intensity

Here is where things get really tricky. For years, emotional dysregulation was not even considered part of ADHD. It was not in the diagnostic criteria. But research by Barkley and others has made it increasingly clear that emotional regulation difficulties are a core feature of ADHD, not just a secondary effect.

This means that ADHD adults often experience intense emotions, rapid mood shifts, irritability, and frustration. Which sounds an awful lot like the mood instability of bipolar disorder.

If you want to explore the emotional side of ADHD further, I have written about ADHD and emotional regulation in detail.

Sleep Problems

Both conditions mess with sleep. ADHD brains struggle to wind down at night, often leading to delayed sleep onset and poor sleep quality. Bipolar disorder involves dramatic shifts in sleep need: very little sleep during mania, excessive sleep during depression.

Difficulty With Focus

People assume that bipolar disorder does not affect concentration, but it absolutely does. During depressive episodes, concentration and motivation plummet. During mania, the mind is so accelerated that sustained focus on a single task becomes impossible. Both can look like the inattention of ADHD.

The Key Differences: A Comparison Table

Right. Here is where we start to pull things apart. Because despite all the overlap, there are meaningful and clinically important differences between ADHD and bipolar disorder.

Why Misdiagnosis Happens

Misdiagnosis between ADHD and bipolar disorder is common enough that it causes real problems. There are a few reasons it keeps happening.

ADHD Was Not Taken Seriously in Adults Until Recently

For decades, ADHD was considered a childhood condition that you grew out of. NICE did not publish its current guideline on adult ADHD (NG87) until 2018, and even now, many mental health professionals have limited training in recognising ADHD in adults. So when an adult presents with impulsivity, emotional instability, and concentration difficulties, the clinician's mind may jump to bipolar or personality disorder before considering ADHD.

Emotional Dysregulation Was Left Out of ADHD Criteria

The DSM-5 diagnostic criteria for ADHD focus on inattention, hyperactivity, and impulsivity. They do not include emotional regulation, even though Barkley has argued for years that it is a central feature of the condition. This means that an adult whose ADHD primarily manifests as emotional volatility may not look like "textbook ADHD" to a clinician who is following the criteria strictly.

Bipolar Screening Tools Can Flag ADHD

This is a sneaky one. Some bipolar screening questionnaires include items about impulsivity, distractibility, and rapid mood changes. An ADHD adult filling one out might score high, not because they have bipolar, but because those features overlap. Without a thorough clinical interview that digs into the pattern and timeline of symptoms, a screening score alone can send the diagnostic process in the wrong direction.

The Consequences of Getting It Wrong

This is not just an academic problem. Getting the diagnosis wrong has real treatment implications.

ADHD is primarily treated with stimulant medication (methylphenidate, lisdexamfetamine). Bipolar disorder is treated with mood stabilisers (lithium, valproate) and sometimes atypical antipsychotics.

If someone with ADHD is incorrectly diagnosed with bipolar and given mood stabilisers, their ADHD symptoms will not improve. They may also experience significant side effects from medication they do not need.

Conversely, if someone with undiagnosed bipolar is given stimulant medication for ADHD, there is a risk of triggering or worsening manic episodes. Research by Kessler et al. (2006) in the American Journal of Psychiatry highlighted the high comorbidity rates between ADHD and mood disorders, and stressed the importance of thorough differential assessment.

This is why a comprehensive assessment matters. If you are not sure what to expect from an assessment, I have a walkthrough of what happens in an ADHD assessment that covers the process.

Can You Have Both? (Yes, You Can)

Here is something that complicates the picture further: ADHD and bipolar disorder are not mutually exclusive. You can absolutely have both.

Studies suggest that around 10-20% of people with bipolar disorder also meet the criteria for ADHD, and that adults with ADHD are at elevated risk of developing bipolar disorder compared to the general population (Kessler et al., 2006).

When both conditions are present, treatment gets more complex. It usually involves:

• Stabilising mood first with appropriate bipolar medication
• Then carefully introducing ADHD-specific treatment (sometimes stimulants at lower doses, sometimes non-stimulant options like atomoxetine)
• Ongoing monitoring, because the interaction between the two conditions requires close attention

If you suspect you might have both, I would strongly encourage you to seek an assessment from a psychiatrist who has experience with both conditions. A GP or general mental health professional may not have the specialist knowledge to tease the two apart.

What ADHD Emotional Reactivity Actually Looks Like

Because emotional dysregulation is the biggest source of confusion, let me describe what it actually looks like in ADHD specifically.

ADHD emotional reactivity tends to be:

• Fast. Emotions flare quickly and intensely, then pass relatively quickly. You might be furious one moment and completely fine twenty minutes later
• Triggered. There is almost always a clear external trigger. A comment, a frustration, a disappointment. It is not random
• Proportionate in direction but not in intensity. You are reacting to something real, but the intensity of your reaction is bigger than the situation warrants
• Not accompanied by other manic features. You do not have grandiosity, reduced need for sleep, pressured speech, or increased goal-directed activity alongside the emotional intensity

Compare this with a bipolar manic episode, which typically involves:

• Sustained elevated or irritable mood lasting at least four days (hypomania) or seven days (mania)
• Reduced need for sleep without feeling tired
• Grandiosity or inflated self-esteem
• Pressured speech and flight of ideas
• Increased goal-directed activity or psychomotor agitation
• Risky behaviour that is clearly out of character

The duration and the cluster of symptoms are what distinguish them clinically. ADHD mood shifts are reactive and brief. Bipolar mood episodes are sustained and involve a broader pattern of symptoms.

If you experience significant mood swings alongside ADHD traits, please do not self-diagnose. Get a thorough assessment. This is exactly the kind of situation where professional evaluation makes a genuine difference. I have also written about the overlap between ADHD and anxiety and ADHD and depression if you want to explore other common comorbidities.

What to Do If You Think You Have Been Misdiagnosed

If you are reading this and thinking, "Hang on, I think my diagnosis might be wrong," here is what I would suggest:

If you are in the UK, you have the right to request a reassessment. NICE guideline NG87 recommends that ADHD should be considered in adults presenting with symptoms of emotional instability, impulsivity, and inattention, particularly if these symptoms have been present since childhood.

You deserve the right diagnosis. Not just a label, but the understanding that comes with it, and the treatment path that actually matches what is going on in your brain.

A Quick Word on ADHD vs Bipolar in Women

I want to flag something specific here. Women are disproportionately affected by misdiagnosis in both conditions. ADHD in women is often missed entirely or misdiagnosed as anxiety or depression. Bipolar II (the form with hypomania rather than full mania) is frequently misdiagnosed as depression, because depressive episodes are more prominent and hypomanic episodes can be subtle.

This means that women presenting with emotional intensity, mood instability, and concentration difficulties are at particularly high risk of either being misdiagnosed or having one condition identified while the other is missed.

If you recognise yourself in this, please advocate for a thorough assessment. You can read more about ADHD vs autism as well, since the three-way overlap between ADHD, autism, and bipolar is something clinicians are increasingly recognising.

How Mentoring Helps With Diagnostic Confusion

I am not a diagnostician. I do not assess people or prescribe medication. But a surprising amount of what I do in mentoring involves helping people untangle their experiences so that when they do see a clinician, they can communicate their history clearly.

Things like:

• Mapping out when symptoms started and how they have changed over time
• Identifying whether mood shifts follow an episodic pattern or are constant
• Understanding which strategies have helped and which have not
• Preparing for assessments so you walk in with the information the clinician needs

Tracking your mood and wellbeing daily can also help build a picture over time. Apps like Sprout are useful for this, because they give you a record to take to appointments rather than relying on memory (which, if you have ADHD, is not always your most reliable tool).

Getting the right diagnosis is one of the most impactful things you can do for your mental health. Everything else, the strategies, the medication, the self-understanding, flows from there. If you are stuck in diagnostic limbo and want support figuring out your next steps, that is something I can absolutely help with.

Ready to talk it through? You can book a free discovery call and we will work out the best way forward, together. No pressure, no commitment, just a conversation.